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Goupell MJ, Stecker GC, Williams BT, Bilokon A, Tollin DJ. The Rapid Decline in Interaural-Time-Difference Sensitivity for Pure Tones Can Be Explained by Peripheral Filtering. J Assoc Res Otolaryngol 2024:10.1007/s10162-024-00949-y. [PMID: 38769250 DOI: 10.1007/s10162-024-00949-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Accepted: 04/28/2024] [Indexed: 05/22/2024] Open
Abstract
PURPOSE The interaural time difference (ITD) is a primary horizontal-plane sound localization cue computed in the auditory brainstem. ITDs are accessible in the temporal fine structure of pure tones with a frequency of no higher than about 1400 Hz. How listeners' ITD sensitivity transitions from very best sensitivity near 700 Hz to impossible to detect within 1 octave currently lacks a fully compelling physiological explanation. Here, it was hypothesized that the rapid decline in ITD sensitivity is dictated not by a central neural limitation but by initial peripheral sound encoding, specifically, the low-frequency (apical) portion of the cochlear excitation pattern produced by a pure tone. METHODS ITD sensitivity was measured in 16 normal-hearing listeners as a joint function of frequency (900-1500 Hz) and level (10-50 dB sensation level). RESULTS Performance decreased with increasing frequency and decreasing sound level. The slope of performance decline was 90 dB/octave, consistent with the low-frequency slope of the cochlear excitation pattern. CONCLUSION Fine-structure ITD sensitivity near 1400 Hz may be conveyed primarily by "off-frequency" activation of neurons tuned to lower frequencies near 700 Hz. Physiologically, this could be realized by having neurons sensitive to fine-structure ITD up to only about 700 Hz. A more extreme model would have only a single narrow channel near 700 Hz that conveys fine-structure ITDs. Such a model is a major simplification and departure from the classic formulation of the binaural display, which consists of a matrix of neurons tuned to a wide range of relevant frequencies and ITDs.
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Affiliation(s)
- Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, 20742, USA.
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD, 20742, USA.
| | - G Christopher Stecker
- Center for Hearing Research, Boys Town National Research Hospital, 555 N 30th St, Omaha, NE, 68131, USA
| | - Brittany T Williams
- Center for Hearing Research, Boys Town National Research Hospital, 555 N 30th St, Omaha, NE, 68131, USA
| | - Anhelina Bilokon
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Daniel J Tollin
- Department of Physiology & Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
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Goupell MJ, Cleary M, Bernstein JG. Letter to the Editor: Discussion of Measurement and Analysis Techniques to Estimate Interaural Place-of-Stimulation Mismatch for Binaural Perception, Re: Staisloff and Aronoff (2021). Comparing Methods for Pairing Electrodes Across Ears With Cochlear Implants, Ear Hear, 42, 1218-1227. Ear Hear 2024; 45:523-527. [PMID: 38372759 PMCID: PMC10990077 DOI: 10.1097/aud.0000000000001390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Affiliation(s)
- Matthew J. Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, USA
| | - Miranda Cleary
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, USA
| | - Joshua G.W. Bernstein
- National Military Audiology and Speech Center, Walter Reed National Military Medical Center, Bethesda, Maryland, USA
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Goupell MJ, Stecker GC, Williams BT, Bilokon A, Tollin DJ. The rapid decline in interaural-time-difference sensitivity for pure tones can be explained by peripheral filtering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.04.551950. [PMID: 37577552 PMCID: PMC10418179 DOI: 10.1101/2023.08.04.551950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Purpose The interaural time difference (ITD) is a primary horizontal-plane sound localization cue computed in the auditory brainstem. ITDs are accessible in the temporal fine structure of pure tones with a frequency of no higher than about 1400 Hz. Explaining how listeners' ITD sensitivity transitions from very best sensitivity near 700 Hz to impossible to detect within 1 octave currently lacks a fully compelling physiological explanation. Here, it was hypothesized that the rapid decline in ITD sensitivity is dictated not by a central neural limitation but by initial peripheral sound encoding, specifically, the low-frequency (apical) edge of the cochlear excitation pattern produced by a pure tone. Methods ITD sensitivity was measured in 16 normal-hearing listeners as a joint function of frequency (900-1500 Hz) and level (10-50 dB sensation level). Results Performance decreased with increasing frequency and decreasing sound level. The slope of performance decline was 90 dB/octave, consistent with the low-frequency slope of the cochlear excitation pattern. Conclusion Fine-structure ITD sensitivity near 1400 Hz may be conveyed primarily by "off-frequency" activation of neurons tuned to lower frequencies near 700 Hz. Physiologically, this could be realized by having neurons sensitive to fine-structure ITD up to only about 700 Hz. A more extreme model would have only a single narrow channel near 700 Hz that conveys fine-structure ITDs. Such a model is a major simplification and departure from the classic formulation of the binaural display, which consists of a matrix of neurons tuned to a wide range of relevant frequencies and ITDs.
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Oh Y, Friggle P, Kinder J, Tilbrook G, Bridges SE. Effects of presentation level on speech-on-speech masking by voice-gender difference and spatial separation between talkers. Front Neurosci 2023; 17:1282764. [PMID: 38192513 PMCID: PMC10773857 DOI: 10.3389/fnins.2023.1282764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/30/2023] [Indexed: 01/10/2024] Open
Abstract
Many previous studies have reported that speech segregation performance in multi-talker environments can be enhanced by two major acoustic cues: (1) voice-characteristic differences between talkers; (2) spatial separation between talkers. Here, the improvement they can provide for speech segregation is referred to as "release from masking." The goal of this study was to investigate how masking release performance with two cues is affected by various target presentation levels. Sixteen normal-hearing listeners participated in the speech recognition in noise experiment. Speech-on-speech masking performance was measured as the threshold target-to-masker ratio needed to understand a target talker in the presence of either same- or different-gender masker talkers to manipulate the voice-gender difference cue. These target-masker gender combinations were tested with five spatial configurations (maskers co-located or 15°, 30°, 45°, and 60° symmetrically spatially separated from the target) to manipulate the spatial separation cue. In addition, those conditions were repeated at three target presentation levels (30, 40, and 50 dB sensation levels). Results revealed that the amount of masking release by either voice-gender difference or spatial separation cues was significantly affected by the target level, especially at the small target-masker spatial separation (±15°). Further, the results showed that the intersection points between two masking release types (equal perceptual weighting) could be varied by the target levels. These findings suggest that the perceptual weighting of masking release from two cues is non-linearly related to the target levels. The target presentation level could be one major factor associated with masking release performance in normal-hearing listeners.
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Affiliation(s)
- Yonghee Oh
- Department of Otolaryngology-Head and Neck Surgery and Communicative Disorders, University of Louisville, Louisville, KY, United States
- Department of Speech, Language, and Hearing Sciences, University of Florida, Gainesville, FL, United States
| | - Phillip Friggle
- Department of Otolaryngology-Head and Neck Surgery and Communicative Disorders, University of Louisville, Louisville, KY, United States
| | - Josephine Kinder
- Department of Otolaryngology-Head and Neck Surgery and Communicative Disorders, University of Louisville, Louisville, KY, United States
| | - Grace Tilbrook
- Department of Speech, Language, and Hearing Sciences, University of Florida, Gainesville, FL, United States
| | - Sarah E. Bridges
- Department of Speech, Language, and Hearing Sciences, University of Florida, Gainesville, FL, United States
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Heil P, Friedrich B. How to define thresholds for level and interaural-level-difference discrimination: Insights from scedasticities and distributions. Hear Res 2023; 436:108837. [PMID: 37413706 DOI: 10.1016/j.heares.2023.108837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 05/31/2023] [Accepted: 06/19/2023] [Indexed: 07/08/2023]
Abstract
Sensitivity to changes in the stimulus level at one or at both ears and to changes in the interaural level difference (ILD) between the two ears has been studied widely. Several different definitions of threshold and, for one of them, two different ways of averaging single-listener thresholds have been used (i.e., arithmetically and geometrically), but it is unclear which definition and which way of averaging is most suitable. Here, we addressed this issue by examining which of the differently defined thresholds yielded the highest degree of homoscedasticity (homogeneity of the variance). We also examined how closely the differently defined thresholds followed the normal distribution. We measured thresholds from a large number of human listeners as a function of stimulus duration in six experimental conditions, using an adaptive two-alternative forced-choice paradigm. Thresholds defined as the logarithm of the ratio of the intensities or amplitudes of the target and the reference stimulus (i.e., as the difference in their levels or ILDs; the most commonly used definition) were clearly heteroscedastic. Log-transformation of these latter thresholds, as sometimes performed, did not result in homoscedasticity. Thresholds defined as the logarithm of the Weber fraction for stimulus intensity and thresholds defined as the logarithm of the Weber fraction for stimulus amplitude (the most rarely used definition) were consistent with homoscedasticity, but the latter were closer to the ideal case. Thresholds defined as the logarithm of the Weber fraction for stimulus amplitude also followed the normal distribution most closely. The discrimination thresholds should therefore be expressed as the logarithm of the Weber fraction for stimulus amplitude and be averaged arithmetically across listeners. Other implications are discussed, and the obtained differences between the thresholds in different conditions are compared to the literature.
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Affiliation(s)
- Peter Heil
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany.
| | - Björn Friedrich
- Department of Experimental Audiology, Otto von Guericke University, Magdeburg, Germany
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Dietze A, Sörös P, Bröer M, Methner A, Pöntynen H, Sundermann B, Witt K, Dietz M. Effects of acute ischemic stroke on binaural perception. Front Neurosci 2022; 16:1022354. [PMID: 36620448 PMCID: PMC9817147 DOI: 10.3389/fnins.2022.1022354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Stroke-induced lesions at different locations in the brain can affect various aspects of binaural hearing, including spatial perception. Previous studies found impairments in binaural hearing, especially in patients with temporal lobe tumors or lesions, but also resulting from lesions all along the auditory pathway from brainstem nuclei up to the auditory cortex. Currently, structural magnetic resonance imaging (MRI) is used in the clinical treatment routine of stroke patients. In combination with structural imaging, an analysis of binaural hearing enables a better understanding of hearing-related signaling pathways and of clinical disorders of binaural processing after a stroke. However, little data are currently available on binaural hearing in stroke patients, particularly for the acute phase of stroke. Here, we sought to address this gap in an exploratory study of patients in the acute phase of ischemic stroke. We conducted psychoacoustic measurements using two tasks of binaural hearing: binaural tone-in-noise detection, and lateralization of stimuli with interaural time- or level differences. The location of the stroke lesion was established by previously acquired MRI data. An additional general assessment included three-frequency audiometry, cognitive assessments, and depression screening. Fifty-five patients participated in the experiments, on average 5 days after their stroke onset. Patients whose lesions were in different locations were tested, including lesions in brainstem areas, basal ganglia, thalamus, temporal lobe, and other cortical and subcortical areas. Lateralization impairments were found in most patients with lesions within the auditory pathway. Lesioned areas at brainstem levels led to distortions of lateralization in both hemifields, thalamus lesions were correlated with a shift of the whole auditory space, whereas some cortical lesions predominantly affected the lateralization of stimuli contralateral to the lesion and resulted in more variable responses. Lateralization performance was also found to be affected by lesions of the right, but not the left, basal ganglia, as well as by lesions in non-auditory cortical areas. In general, altered lateralization was common in the stroke group. In contrast, deficits in tone-in-noise detection were relatively scarce in our sample of lesion patients, although a significant number of patients with multiple lesion sites were not able to complete the task.
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Affiliation(s)
- Anna Dietze
- Department of Medical Physics and Acoustics, University of Oldenburg, Oldenburg, Germany,Cluster of Excellence “Hearing4all”, University of Oldenburg, Oldenburg, Germany,*Correspondence: Anna Dietze,
| | - Peter Sörös
- Department of Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Matthias Bröer
- Department of Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Anna Methner
- Department of Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Henri Pöntynen
- Department of Medical Physics and Acoustics, University of Oldenburg, Oldenburg, Germany,Cluster of Excellence “Hearing4all”, University of Oldenburg, Oldenburg, Germany
| | - Benedikt Sundermann
- Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany,Institute of Radiology and Neuroradiology, Evangelisches Krankenhaus Oldenburg, Oldenburg, Germany
| | - Karsten Witt
- Department of Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Mathias Dietz
- Department of Medical Physics and Acoustics, University of Oldenburg, Oldenburg, Germany,Cluster of Excellence “Hearing4all”, University of Oldenburg, Oldenburg, Germany,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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Hu H, Klug J, Dietz M. Simulation of ITD-Dependent Single-Neuron Responses Under Electrical Stimulation and with Amplitude-Modulated Acoustic Stimuli. J Assoc Res Otolaryngol 2022; 23:535-550. [PMID: 35334001 PMCID: PMC9437183 DOI: 10.1007/s10162-021-00823-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 11/03/2021] [Indexed: 11/30/2022] Open
Abstract
Interaural time difference (ITD) sensitivity with cochlear implant stimulation is remarkably similar to envelope ITD sensitivity using conventional acoustic stimulation. This holds true for human perception, as well as for neural response rates recorded in the inferior colliculus of several mammalian species. We hypothesize that robust excitatory-inhibitory (EI) interaction is the dominant mechanism. Therefore, we connected the same single EI-model neuron to either a model of the normal acoustic auditory periphery or to a model of the electrically stimulated auditory nerve. The model captured most features of the experimentally obtained response properties with electric stimulation, such as the shape of rate-ITD functions, the dependence on stimulation level, and the pulse rate or modulation-frequency dependence. Rate-ITD functions with high-rate, amplitude-modulated electric stimuli were very similar to their acoustic counterparts. Responses obtained with unmodulated electric pulse trains most resembled acoustic filtered clicks. The fairly rapid decline of ITD sensitivity at rates above 300 pulses or cycles per second is correctly simulated by the 3.1-ms time constant of the inhibitory post-synaptic conductance. As the model accounts for these basic properties, it is expected to help in understanding and quantifying the binaural hearing abilities with electric stimulation when integrated in bigger simulation frameworks.
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Affiliation(s)
- Hongmei Hu
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany.
| | - Jonas Klug
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany
| | - Mathias Dietz
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany
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Rosen B, Goupell MJ. The effect of target and interferer frequency on across-frequency binaural interference of interaural-level-difference sensitivity. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:924. [PMID: 35232088 PMCID: PMC8837388 DOI: 10.1121/10.0009398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 01/13/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
Across-frequency binaural interference occurs when the sensitivity to changes in interaural differences in a target sound is decreased by a spectrally remote diotic interfering sound. For interaural time differences (ITDs), low-frequency (e.g., 0.5 kHz) interferers cause more interference on high-frequency (e.g., 4 kHz) targets than vice versa. For interaural level differences (ILDs), however, it is unclear if a frequency dependence exists. Therefore, ILD discrimination thresholds and across-frequency binaural interference were measured for target and interferer frequencies between 0.5 and 8 kHz (for tones) or 12 kHz (for narrowband noises). For tones, 8-kHz targets experienced the least interference and 8-kHz interferers produced the most interference, suggesting that higher-frequency ILDs are a more heavily weighted localization cue than lower-frequency ILDs. For narrowband noises, the frequency-dependent interference patterns increased in complexity in comparison to tones. Low-frequency ITD dominance (from randomly varying onset ITDs) and grouping cues (e.g., envelope modulations) might explain some of the complexity in the interference patterns for the noises. These data contribute to a better understanding of across-frequency ILD processing, which remains poorly understood.
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Affiliation(s)
- Beth Rosen
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
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Best V, Baltzell LS, Colburn HS. Effects of Hearing Loss on Interaural Time Difference Sensitivity at Low and High Frequencies. Trends Hear 2022; 26:23312165221095357. [PMID: 35754372 PMCID: PMC9244940 DOI: 10.1177/23312165221095357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
While many studies have reported a loss of sensitivity to interaural time differences (ITDs) carried in the fine structure of low-frequency signals for listeners with hearing loss, relatively few data are available on the perception of ITDs carried in the envelope of high-frequency signals in this population. The relevant studies found stronger effects of hearing loss at high frequencies than at low frequencies in most cases, but small subject numbers and several confounding effects prevented strong conclusions from being drawn. In the present study, we revisited this question while addressing some of the issues identified in previous studies. Participants were ten young adults with normal hearing (NH) and twenty adults with sensorineural hearing impairment (HI) spanning a range of ages. ITD discrimination thresholds were measured for octave-band-wide “rustle” stimuli centered at 500 Hz or 4000 Hz, which were presented at 20 or 40 dB sensation level. Broadband rustle stimuli and 500-Hz pure-tone stimuli were also tested. Thresholds were poorer on average for the HI group than the NH group. The ITD deficit, relative to the NH group, was similar at low and high frequencies for most HI participants. For a small number of participants, however, the deficit was strongly frequency-dependent. These results provide new insights into the binaural perception of complex sounds and may inform binaural models that incorporate effects of hearing loss.
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Affiliation(s)
- Virginia Best
- Department of Speech, Language and Hearing Sciences, 1846Boston University, Boston, MA, United States
| | - Lucas S Baltzell
- Department of Speech, Language and Hearing Sciences, 1846Boston University, Boston, MA, United States
| | - H Steven Colburn
- Department of Biomedical Engineering, 1846Boston University, Boston, MA, United States
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Mayo PG, Saunders PC, Goupell MJ. Interaural-time-difference thresholds for broad band-limited pulses are affected by relative bandwidth not temporal envelope sharpness. JASA EXPRESS LETTERS 2021; 1:124401. [PMID: 34927162 PMCID: PMC8667050 DOI: 10.1121/10.0008971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/21/2021] [Indexed: 06/14/2023]
Abstract
Humans are sensitive to interaural time differences (ITDs) conveyed by slow modulations on high-frequency carrier signals. Sensitivity appears to be affected by temporal envelope sharpness, but it is unclear if there is a limit to which sharpness affects sensitivity. Pulse trains were varied in relative bandwidth (re: critical bandwidths) and center frequency. ITD sensitivity increased with increasing bandwidth. There was no effect of center frequency when relative bandwidths were analyzed, suggesting that the temporal envelope sharpness (concomitantly absolute bandwidth in Hz) did not affect performance. Rather, sensitivity was most easily explained by recruitment of additional auditory channels.
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Affiliation(s)
- Paul G Mayo
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA , ,
| | - Philip C Saunders
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA , ,
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA , ,
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Goldsworthy RL, Camarena A, Bissmeyer SRS. Pitch perception is more robust to interference and better resolved when provided by pulse rate than by modulation frequency of cochlear implant stimulation. Hear Res 2021; 409:108319. [PMID: 34340020 DOI: 10.1016/j.heares.2021.108319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/15/2021] [Accepted: 07/21/2021] [Indexed: 01/14/2023]
Abstract
Cochlear implants are medical devices that have been used to restore hearing to more than half a million people worldwide. Most recipients achieve high levels of speech comprehension through these devices, but speech comprehension in background noise and music appreciation in general are markedly poor compared to normal hearing. A key aspect of hearing that is notably diminished in cochlear implant outcomes is the sense of pitch provided by these devices. Pitch perception is an important factor affecting speech comprehension in background noise and is critical for music perception. The present article summarizes two experiments that examine the robustness and resolution of pitch perception as provided by cochlear implant stimulation timing. The driving hypothesis is that pitch conveyed by stimulation timing cues is more robust and better resolved when provided by variable pulse rates than by modulation frequency of constant-rate stimulation. Experiment 1 examines the robustness for hearing a large, one-octave, pitch difference in the presence of interfering electrical stimulation. With robustness to interference characterized for an otherwise easily discernible pitch difference, Experiment 2 examines the resolution of discrimination thresholds in the presence of interference as conveyed by modulation frequency or by pulse rate. These experiments test for an advantage of stimulation with precise temporal cues. The results indicate that pitch provided by pulse rate is both more robust to interference and is better resolved compared to when provided by modulation frequency. These results should inform the development of new sound processing strategies for cochlear implants designed to encode fundamental frequency of sounds into precise temporal stimulation.
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Affiliation(s)
- Raymond L Goldsworthy
- Auditory Research Center, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
| | - Andres Camarena
- Auditory Research Center, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States; Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Susan R S Bissmeyer
- Auditory Research Center, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States; Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
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Haywood NR, Undurraga JA, McAlpine D. The influence of envelope shape on the lateralization of amplitude-modulated, low-frequency sound. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:3133. [PMID: 34241105 DOI: 10.1121/10.0004788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 04/06/2021] [Indexed: 06/13/2023]
Abstract
For abruptly gated sound, interaural time difference (ITD) cues at onset carry greater perceptual weight than those following. This research explored how envelope shape influences such carrier ITD weighting. Experiment 1 assessed the perceived lateralization of a tonal binaural beat that transitioned through ITD (diotic envelope, mean carrier frequency of 500 Hz). Listeners' left/right lateralization judgments were compared to those for static-ITD tones. For an 8 Hz sinusoidally amplitude-modulated envelope, ITD cues 24 ms after onset well-predicted reported sidedness. For an equivalent-duration "abrupt" envelope, which was unmodulated besides 20-ms onset/offset ramps, reported sidedness corresponded to ITDs near onset (e.g., 6 ms). However, unlike for sinusoidal amplitude modulation, ITDs toward offset seemingly also influenced perceived sidedness. Experiment 2 adjusted the duration of the offset ramp (25-75 ms) and found evidence for such offset weighting only for the most abrupt ramp tested. In experiment 3, an ITD was imposed on a brief segment of otherwise diotic filtered noise. Listeners discriminated right- from left-leading ITDs. In sinusoidal amplitude modulation, thresholds were lowest when the ITD segment occurred during rising amplitude. For the abrupt envelope, the lowest thresholds were observed when the segment occurred at either onset or offset. These experiments demonstrate the influence of envelope profile on carrier ITD sensitivity.
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Affiliation(s)
- Nicholas R Haywood
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Jaime A Undurraga
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
| | - David McAlpine
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
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Abstract
Hearing aid and cochlear implant (CI) users often struggle to locate and segregate sounds. The dominant sound-localisation cues are time and intensity differences across the ears. A recent study showed that CI users locate sounds substantially better when these cues are provided through haptic stimulation on each wrist. However, the sensitivity of the wrists to these cues and the robustness of this sensitivity to aging is unknown. The current study showed that time difference sensitivity is much poorer across the wrists than across the ears and declines with age. In contrast, high sensitivity to across-wrist intensity differences was found that was robust to aging. This high sensitivity was observed across a range of stimulation intensities for both amplitude modulated and unmodulated sinusoids and matched across-ear intensity difference sensitivity for normal-hearing individuals. Furthermore, the usable dynamic range for haptic stimulation on the wrists was found to be around four times larger than for CIs. These findings suggest that high-precision haptic sound-localisation can be achieved, which could aid many hearing-impaired listeners. Furthermore, the finding that high-fidelity across-wrist intensity information can be transferred could be exploited in human-machine interfaces to enhance virtual reality and improve remote control of military, medical, or research robots.
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Anderson SR, Easter K, Goupell MJ. Effects of rate and age in processing interaural time and level differences in normal-hearing and bilateral cochlear-implant listeners. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3232. [PMID: 31795662 PMCID: PMC6948219 DOI: 10.1121/1.5130384] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 09/27/2019] [Accepted: 10/02/2019] [Indexed: 05/25/2023]
Abstract
Bilateral cochlear implants (BICIs) provide improved sound localization and speech understanding in noise compared to unilateral CIs. However, normal-hearing (NH) listeners demonstrate superior binaural processing abilities compared to BICI listeners. This investigation sought to understand differences between NH and BICI listeners' processing of interaural time differences (ITDs) and interaural level differences (ILDs) as a function of fine-structure and envelope rate using an intracranial lateralization task. The NH listeners were presented band-limited acoustical pulse trains and sinusoidally amplitude-modulated tones using headphones, and the BICI listeners were presented single-electrode electrical pulse trains using direct stimulation. Lateralization range increased as fine-structure rate increased for ILDs in BICI listeners. Lateralization range decreased for rates above 100 Hz for fine-structure ITDs, but decreased for rates lower or higher than 100 Hz for envelope ITDs in both groups. Lateralization ranges for ITDs were smaller for BICI listeners on average. After controlling for age, older listeners showed smaller lateralization ranges and BICI listeners had a more rapid decline for ITD sensitivity at 300 pulses per second. This work suggests that age confounds comparisons between NH and BICI listeners in temporal processing tasks and that some NH-BICI binaural processing differences persist even when age differences are adequately addressed.
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Affiliation(s)
- Sean R Anderson
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Kyle Easter
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
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Ihlefeld A, Alamatsaz N, Shapley RM. Population rate-coding predicts correctly that human sound localization depends on sound intensity. eLife 2019; 8:47027. [PMID: 31633481 PMCID: PMC6802950 DOI: 10.7554/elife.47027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/20/2019] [Indexed: 12/02/2022] Open
Abstract
Human sound localization is an important computation performed by the brain. Models of sound localization commonly assume that sound lateralization from interaural time differences is level invariant. Here we observe that two prevalent theories of sound localization make opposing predictions. The labelled-line model encodes location through tuned representations of spatial location and predicts that perceived direction is level invariant. In contrast, the hemispheric-difference model encodes location through spike-rate and predicts that perceived direction becomes medially biased at low sound levels. Here, behavioral experiments find that softer sounds are perceived closer to midline than louder sounds, favoring rate-coding models of human sound localization. Analogously, visual depth perception, which is based on interocular disparity, depends on the contrast of the target. The similar results in hearing and vision suggest that the brain may use a canonical computation of location: encoding perceived location through population spike rate relative to baseline. Being able to localize sounds helps us make sense of the world around us. The brain works out sound direction by comparing the times of when sound reaches the left versus the right ear. This cue is known as interaural time difference, or ITD for short. But how exactly the brain decodes this information is still unknown. The brain contains nerve cells that each show maximum activity in response to one particular ITD. One idea is that these nerve cells are arranged in the brain like a map from left to right, and that the brain then uses this map to estimate sound direction. This is known as the Jeffress model, after the scientist who first proposed it. There is some evidence that birds and alligators actually use a system like this to localize sounds, but no such map of nerve cells has yet been identified in mammals. An alternative possibility is that the brain compares activity across groups of ITD-sensitive nerve cells. One of the oldest and simplest ways to measure this is to compare nerve activity in the left and right hemispheres of the brain. This readout is known as the hemispheric difference model. By analyzing data from published studies, Ihlefeld, Alamatsaz, and Shapley discovered that these two models make opposing predictions about the effects of volume. The Jeffress model predicts that the volume of a sound will not affect a person’s ability to localize it. By contrast, the hemispheric difference model predicts that very soft sounds will lead to systematic errors, so that for the same ITD, softer sounds are perceived closer towards the front than louder sounds. To investigate this further, Ihlefeld, Alamatsaz, and Shapley asked healthy volunteers to localize sounds of different volumes. The volunteers tended to mis-localize quieter sounds, believing them to be closer to the body’s midline than they actually were, which is inconsistent with the predictions of the Jeffress model. These new findings also reveal key parallels to processing in the visual system. Visual areas of the brain estimate how far away an object is by comparing the input that reaches the two eyes. But these estimates are also systematically less accurate for low-contrast stimuli than for high-contrast ones, just as sound localization is less accurate for softer sounds than for louder ones. The idea that the brain uses the same basic strategy to localize both sights and sounds generates a number of predictions for future studies to test.
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Affiliation(s)
- Antje Ihlefeld
- New Jersey Institute of Technology, Newark, United States
| | - Nima Alamatsaz
- New Jersey Institute of Technology, Newark, United States.,Rutgers University, Newark, United States
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16
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Goupell MJ, Fong S, Stakhovskaya O. The effect of envelope modulations on binaural processing. Hear Res 2019; 379:117-127. [PMID: 31154164 DOI: 10.1016/j.heares.2019.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/29/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
Abstract
An experiment was performed with 10 young normal-hearing listeners that attempted to determine if envelope modulations affected binaural processing in bandlimited pulse trains. Listeners detected an interaurally out-of-phase carrier pulse train in the presence of different amplitude modulations. The peaks of the pulses were constant (called "flat" or F), followed envelope modulations from an interaurally correlated 50-Hz bandwidth noise (called CM), or followed modulations from an interaurally uncorrelated noise (called UM). The pulse rate was varied from 50 to 500 pulses per second (pps) and the center frequency (CF) was 4 or 8 kHz. It was hypothesized that CM would cause no change or an increase in performance compared to F; UM would cause a decrease because of the blurring of the binaural detection cue. There was a small but significant decrease from F to CM (inconsistent with the hypothesis) and a further decrease from CM to UM (consistent with the hypothesis). Critically, there was a significant envelope by rate interaction caused by a decrease from F to CM for the 200-300 pps rates. The data can be explained by a subject-based factor, where some listeners experienced interaural envelope decorrelation when the sound was encoded by the auditory system that reduced performance when the modulations were present. Since the decrease in performance between F and CM conditions was small, it seems that most young normal-hearing listeners have very similar encoding of modulated stimuli across the ears. This type of task, when further optimized, may be able to assess if hearing-impaired populations experience interaural decorrelation from encoding modulated stimuli and therefore could help better understand the limited spatial hearing in populations like cochlear-implant users.
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Affiliation(s)
- Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, 20742, USA.
| | - Stephen Fong
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Olga Stakhovskaya
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, 20742, USA
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17
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Moore BCJ. Effects of age on sensitivity to interaural time differences in envelope and fine structure, individually and in combination. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:1287. [PMID: 29604696 PMCID: PMC5834318 DOI: 10.1121/1.5025845] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/08/2018] [Accepted: 02/10/2018] [Indexed: 06/01/2023]
Abstract
Sensitivity to interaural time differences (ITDs) in envelope and temporal fine structure (TFS) of amplitude-modulated (AM) tones was assessed for young and older subjects, all with clinically normal hearing at the carrier frequencies of 250 and 500 Hz. Some subjects had hearing loss at higher frequencies. In experiment 1, thresholds for detecting changes in ITD were measured when the ITD was present in the TFS alone (ITDTFS), the envelope alone (ITDENV), or both (ITDTFS/ENV). Thresholds tended to be higher for the older than for the young subjects. ITDENV thresholds were much higher than ITDTFS thresholds, while ITDTFS/ENV thresholds were similar to ITDTFS thresholds. ITDTFS thresholds were lower than ITD thresholds obtained with an unmodulated pure tone, indicating that uninformative AM can improve ITDTFS discrimination. In experiment 2, equally detectable values of ITDTFS and ITDENV were combined so as to give consistent or inconsistent lateralization. There were large individual differences, but several subjects gave scores that were much higher than would be expected from the optimal combination of independent sources of information, even for the inconsistent condition. It is suggested that ITDTFS and ITDENV cues are processed partly independently, but that both cues influence lateralization judgments, even when one cue is uninformative.
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18
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The Relationship Between Intensity Coding and Binaural Sensitivity in Adults With Cochlear Implants. Ear Hear 2018; 38:e128-e141. [PMID: 27787393 DOI: 10.1097/aud.0000000000000382] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Many bilateral cochlear implant users show sensitivity to binaural information when stimulation is provided using a pair of synchronized electrodes. However, there is large variability in binaural sensitivity between and within participants across stimulation sites in the cochlea. It was hypothesized that within-participant variability in binaural sensitivity is in part affected by limitations and characteristics of the auditory periphery which may be reflected by monaural hearing performance. The objective of this study was to examine the relationship between monaural and binaural hearing performance within participants with bilateral cochlear implants. DESIGN Binaural measures included dichotic signal detection and interaural time difference discrimination thresholds. Diotic signal detection thresholds were also measured. Monaural measures included dynamic range and amplitude modulation detection. In addition, loudness growth was compared between ears. Measures were made at three stimulation sites per listener. RESULTS Greater binaural sensitivity was found with larger dynamic ranges. Poorer interaural time difference discrimination was found with larger difference between comfortable levels of the two ears. In addition, poorer diotic signal detection thresholds were found with larger differences between the dynamic ranges of the two ears. No relationship was found between amplitude modulation detection thresholds or symmetry of loudness growth and the binaural measures. CONCLUSIONS The results suggest that some of the variability in binaural hearing performance within listeners across stimulation sites can be explained by factors nonspecific to binaural processing. The results are consistent with the idea that dynamic range and comfortable levels relate to peripheral neural survival and the width of the excitation pattern which could affect the fidelity with which central binaural nuclei process bilateral inputs.
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19
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Goupell MJ, Stakhovskaya OA. Across-channel interaural-level-difference processing demonstrates frequency dependence. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:645. [PMID: 29495743 PMCID: PMC5798994 DOI: 10.1121/1.5021552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 12/28/2017] [Accepted: 01/04/2018] [Indexed: 06/08/2023]
Abstract
Accurate localization of complex sounds involves combining interaural information across frequencies to produce a single location percept. Interaural level differences (ILDs) are highly frequency dependent and it is unclear how the auditory system combines differing ILDs across frequency. Therefore, ILD just noticeable differences (JNDs) and intracranial lateralization were measured in young normal-hearing listeners using single- and multi-band stimuli. The bands were 300-ms, 10-Hz narrowband noises; the multi-band condition had three bands; they started and ended synchronously; they were located around three different frequency regions (750, 2000, or 4000 Hz); they had five different frequency separations that ranged from unresolved to resolved; the bands were dichotic with the same non-zero ILD (targets) or were diotic with zero ILD (interferers). Results showed single-band ILD JNDs were marginally frequency dependent. If unresolved diotic interferers were added, ILD JNDs increased greatly because of interaural decorrelation. If well-resolved diotic interferers were added, ILD JNDs were frequency dependent and the worst performance occurred when targets were near 1000 or 4000 Hz. This frequency dependence might be partially explained by ILD vs azimuth non-monotonicities for free-field sound sources in this frequency region. These results suggest that binaural processing models need revision for the processing of complex sounds.
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Affiliation(s)
- Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Olga A Stakhovskaya
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
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20
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Dietz M, Lestang JH, Majdak P, Stern RM, Marquardt T, Ewert SD, Hartmann WM, Goodman DFM. A framework for testing and comparing binaural models. Hear Res 2017; 360:92-106. [PMID: 29208336 DOI: 10.1016/j.heares.2017.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/03/2017] [Accepted: 11/24/2017] [Indexed: 11/19/2022]
Abstract
Auditory research has a rich history of combining experimental evidence with computational simulations of auditory processing in order to deepen our theoretical understanding of how sound is processed in the ears and in the brain. Despite significant progress in the amount of detail and breadth covered by auditory models, for many components of the auditory pathway there are still different model approaches that are often not equivalent but rather in conflict with each other. Similarly, some experimental studies yield conflicting results which has led to controversies. This can be best resolved by a systematic comparison of multiple experimental data sets and model approaches. Binaural processing is a prominent example of how the development of quantitative theories can advance our understanding of the phenomena, but there remain several unresolved questions for which competing model approaches exist. This article discusses a number of current unresolved or disputed issues in binaural modelling, as well as some of the significant challenges in comparing binaural models with each other and with the experimental data. We introduce an auditory model framework, which we believe can become a useful infrastructure for resolving some of the current controversies. It operates models over the same paradigms that are used experimentally. The core of the proposed framework is an interface that connects three components irrespective of their underlying programming language: The experiment software, an auditory pathway model, and task-dependent decision stages called artificial observers that provide the same output format as the test subject.
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Affiliation(s)
- Mathias Dietz
- National Centre for Audiology, Western University, London, ON, Canada.
| | - Jean-Hugues Lestang
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
| | - Piotr Majdak
- Institut für Schallforschung, Österreichische Akademie der Wissenschaften, Wien, Austria
| | | | | | - Stephan D Ewert
- Medizinische Physik, Universität Oldenburg, Oldenburg, Germany
| | | | - Dan F M Goodman
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
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21
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Laback B, Dietz M, Joris P. Temporal effects in interaural and sequential level difference perception. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:3267. [PMID: 29195428 DOI: 10.1121/1.5009563] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Temporal effects in interaural level difference (ILD) perception are not well understood. While it is often assumed that ILD sensitivity is independent of the temporal stimulus properties, a reduction of ILD sensitivity for stimuli with a high modulation rate has been reported (known under the term binaural adaptation). Experiment 1 compared ILD thresholds and sequential-level-difference (SLD) thresholds using 300-ms bandpass-filtered pulse trains (centered at 4 kHz) with rates of 100, 400, and 800 pulses per second (pps). In contrast to the SLD thresholds, ILD thresholds were elevated at 800 pps, consistent with literature data that had previously been attributed to binaural adaptation. Experiment 2 showed better ILD sensitivity for pulse trains than for pure tones, suggesting that amplitude modulation enhances ILD sensitivity. The present ILD data and binaural adaptation data from the literature were predicted by a model combining well-established auditory periphery front-ends with an interaural comparison stage. The model also accounted for other published ILD data, including target ILD thresholds in diotic forward and backward fringes and ILD thresholds with different amounts of interaural correlation. Overall, a variety of temporal effects in ILD perception, including binaural adaptation, appear to be largely attributable to monaural peripheral auditory processing.
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Affiliation(s)
- Bernhard Laback
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, Vienna, A-1040, Austria
| | - Mathias Dietz
- Medizinische Physik, Universität Oldenburg, Carl-von-Ossietzky Straße 9-11, Oldenburg, 26111, Germany
| | - Philip Joris
- Laboratory of Auditory Neurophysiology, KU Leuven, Herestraat 49, Leuven, B-3000, Belgium
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22
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Egger K, Majdak P, Laback B. Binaural timing information in electric hearing at low rates: Effects of inaccurate encoding and loudness. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:3164. [PMID: 28599571 DOI: 10.1121/1.4982888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Stimulation strategies for cochlear implants potentially impose timing limitations that may hinder the correct encoding and representation of interaural time differences (ITDs) in realistic bilateral signals. This study aimed to specify the tolerable room for inaccurate encoding of ITDs at low rates by investigating the perceptual degradation due to the removal of individual pulses at various levels of loudness. Unmodulated, 100-pulses-per-second pulse trains were presented at a single, interaurally pitch-matched electrode pair. In experiment I, ITD thresholds were measured applying different degrees of bilateral, interaurally-uncorrelated pulse removal. The ITD sensitivity deteriorated with increasing degree of pulse removal, with significant deterioration for degrees of 16% or greater. In experiment II, the interaction between loudness and pulse removal was investigated. Louder stimuli yielded better ITD sensitivity, however, no further improvement was found for stimuli louder than "medium." When removing 8% of the pulses, the ITD sensitivity deteriorated significantly across the entire loudness range tested. A loudness-induced compensation for the deterioration of ITD sensitivity due to pulse removal seems to be feasible for soft stimuli but not for medium or loud stimuli. Overall, our findings suggest that the degree of pulse removal employed in low-rate channels within coding strategies should not exceed 8%.
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Affiliation(s)
- Katharina Egger
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, A-1040 Vienna, Austria
| | - Piotr Majdak
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, A-1040 Vienna, Austria
| | - Bernhard Laback
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, A-1040 Vienna, Austria
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23
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Hu H, Ewert SD, McAlpine D, Dietz M. Differences in the temporal course of interaural time difference sensitivity between acoustic and electric hearing in amplitude modulated stimuli. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:1862. [PMID: 28372072 DOI: 10.1121/1.4977014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Previous studies have shown that normal-hearing (NH) listeners' spatial perception of non-stationary interaural time differences (ITDs) is dominated by the carrier ITD during rising amplitude segments. Here, ITD sensitivity throughout the amplitude-modulation cycle in NH listeners and bilateral cochlear implant (CI) subjects is compared, the latter by means of direct stimulation of a single electrode pair. The data indicate that, while NH listeners are most sensitive to ITDs applied toward the beginning of a modulation cycle at 600 Hz, NH listeners at 200 Hz and especially bilateral CI subjects at 200 pulses per second (pps) are more sensitive to ITDs applied to the modulation maximum. This has implications for spatial-hearing in complex environments: NH listeners' dominant 600-Hz ITD information from the rising amplitude segments comprises direct sound information. The 200-pps low rate required to get ITD sensitivity in CI users results in a higher weight of pulses later in the modulation cycle where the source ITDs are more likely corrupted by reflections. This indirectly indicates that even if future binaural CI processors are able to provide perceptually exploitable ITD information, CI users will likely not get the full benefit from such pulse-based ITD cues in reverberant and other complex environments.
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Affiliation(s)
- Hongmei Hu
- Medizinische Physik and Cluster of Excellence "Hearing4all," Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Stephan D Ewert
- Medizinische Physik and Cluster of Excellence "Hearing4all," Universität Oldenburg, D-26111 Oldenburg, Germany
| | - David McAlpine
- Department of Linguistics, Australian Hearing Hub, Macquarie University, New South Wales 2109, Australia
| | - Mathias Dietz
- Medizinische Physik and Cluster of Excellence "Hearing4all," Universität Oldenburg, D-26111 Oldenburg, Germany
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24
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Macaulay EJ, Rakerd B, Andrews TJ, Hartmann WM. On the localization of high-frequency, sinusoidally amplitude-modulated tones in free field. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:847. [PMID: 28253653 PMCID: PMC6910042 DOI: 10.1121/1.4976047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 01/18/2017] [Accepted: 01/18/2017] [Indexed: 06/06/2023]
Abstract
Previous headphone experiments have shown that listeners can lateralize high-frequency sine-wave amplitude-modulated (SAM) tones based on interaural time differences in the envelope. However, when SAM tones are presented to listeners in free field or in a room, diffraction by the head or reflections from room surfaces alter the modulation percentages and change the shapes of the envelopes, potentially degrading the envelope cue. Amplitude modulation is transformed into mixed modulation. This article presents a mathematical transformation between the six spectral parameters for a modulated tone and six mixed-modulation parameters for each ear. The transformation was used to characterize the stimuli in the ear canals of listeners in free-field localization experiments. The mixed modulation parameters were compared with the perceived changes in localization attributable to the modulation for five different listeners, who benefited from the modulation to different extents. It is concluded that individual differences in the response to added modulation were not systematically related to the physical modulation parameters themselves. Instead, they were likely caused by individual differences in processing of envelope interaural time differences.
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Affiliation(s)
- Eric J Macaulay
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Road, East Lansing, Michigan 48824, USA
| | - Brad Rakerd
- Department of Communicative Sciences and Disorders, Michigan State University, 1026 Red Cedar Road, East Lansing, Michigan 48824, USA
| | - Thomas J Andrews
- Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana 47907, USA
| | - William M Hartmann
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Road, East Lansing, Michigan 48824, USA
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25
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Spencer NJ, Hawley ML, Colburn HS. Relating interaural difference sensitivities for several parameters measured in normal-hearing and hearing-impaired listeners. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:1783. [PMID: 27914394 PMCID: PMC5035301 DOI: 10.1121/1.4962444] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Just-noticeable differences (JNDs) in interaural time delay (ITD), interaural level difference (ILD), and interaural cross-correlation (ICC) were measured with low- and high-frequency noise bands over multiple sessions for 10 normal-hearing (NH) and 11 hearing-impaired (HI) listeners. Individual subject thresholds tended to improve with training then stabilize. Measured JNDs varied over these experienced listeners, for both subject groups and all tasks. Group JNDs were seldom predictable from hearing level. Individual listeners' JNDs were highly correlated across frequency for each task and group, except for ICC in the HI listeners. Further, ITD JNDs almost always significantly correlated with ILD JNDs within a group. Finally, although the ICC JNDs always significantly correlated with the ITD or ILD JNDs for the NH listeners, they often did not for the HI listeners. These findings suggest that little information about binaural sensitivity is added for NH listeners with multiple ITD, ILD, and ICC measures. For HI listeners, however, while ITD and ILD measures are well correlated, information is added with ICC measures. In general, the results suggest that less information is added with JND measures for NH listeners (15 significant correlations) than for HI listeners (six significant correlations).
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Affiliation(s)
- Nathaniel J Spencer
- Department of Biomedical Engineering, Hearing Research Center, Boston University, 44 Cummington Street, Boston, Massachusetts 02215, USA
| | - Monica L Hawley
- Department of Biomedical Engineering, Hearing Research Center, Boston University, 44 Cummington Street, Boston, Massachusetts 02215, USA
| | - H Steven Colburn
- Department of Biomedical Engineering, Hearing Research Center, Boston University, 44 Cummington Street, Boston, Massachusetts 02215, USA
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26
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Todd AE, Goupell MJ, Litovsky RY. Binaural release from masking with single- and multi-electrode stimulation in children with cochlear implants. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:59. [PMID: 27475132 PMCID: PMC5392083 DOI: 10.1121/1.4954717] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Cochlear implants (CIs) provide children with access to speech information from a young age. Despite bilateral cochlear implantation becoming common, use of spatial cues in free field is smaller than in normal-hearing children. Clinically fit CIs are not synchronized across the ears; thus binaural experiments must utilize research processors that can control binaural cues with precision. Research to date has used single pairs of electrodes, which is insufficient for representing speech. Little is known about how children with bilateral CIs process binaural information with multi-electrode stimulation. Toward the goal of improving binaural unmasking of speech, this study evaluated binaural unmasking with multi- and single-electrode stimulation. Results showed that performance with multi-electrode stimulation was similar to the best performance with single-electrode stimulation. This was similar to the pattern of performance shown by normal-hearing adults when presented an acoustic CI simulation. Diotic and dichotic signal detection thresholds of the children with CIs were similar to those of normal-hearing children listening to a CI simulation. The magnitude of binaural unmasking was not related to whether the children with CIs had good interaural time difference sensitivity. Results support the potential for benefits from binaural hearing and speech unmasking in children with bilateral CIs.
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Affiliation(s)
- Ann E Todd
- Waisman Center, University of Wisconsin-Madison, 1500 Highland Avenue, Madison, Wisconsin 53705, USA
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Ruth Y Litovsky
- Waisman Center, University of Wisconsin-Madison, 1500 Highland Avenue, Madison, Wisconsin 53705, USA
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27
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Monaghan JJM, Bleeck S, McAlpine D. Sensitivity to Envelope Interaural Time Differences at High Modulation Rates. Trends Hear 2015; 19:2331216515619331. [PMID: 26721926 PMCID: PMC4871209 DOI: 10.1177/2331216515619331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Sensitivity to interaural time differences (ITDs) conveyed in the temporal fine structure of low-frequency tones and the modulated envelopes of high-frequency sounds are considered comparable, particularly for envelopes shaped to transmit similar fidelity of temporal information normally present for low-frequency sounds. Nevertheless, discrimination performance for envelope modulation rates above a few hundred Hertz is reported to be poor-to the point of discrimination thresholds being unattainable-compared with the much higher (>1,000 Hz) limit for low-frequency ITD sensitivity, suggesting the presence of a low-pass filter in the envelope domain. Further, performance for identical modulation rates appears to decline with increasing carrier frequency, supporting the view that the low-pass characteristics observed for envelope ITD processing is carrier-frequency dependent. Here, we assessed listeners' sensitivity to ITDs conveyed in pure tones and in the modulated envelopes of high-frequency tones. ITD discrimination for the modulated high-frequency tones was measured as a function of both modulation rate and carrier frequency. Some well-trained listeners appear able to discriminate ITDs extremely well, even at modulation rates well beyond 500 Hz, for 4-kHz carriers. For one listener, thresholds were even obtained for a modulation rate of 800 Hz. The highest modulation rate for which thresholds could be obtained declined with increasing carrier frequency for all listeners. At 10 kHz, the highest modulation rate at which thresholds could be obtained was 600 Hz. The upper limit of sensitivity to ITDs conveyed in the envelope of high-frequency modulated sounds appears to be higher than previously considered.
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Affiliation(s)
| | - Stefan Bleeck
- Institute of Sound and Vibration Research, University of Southampton, UK
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Egger K, Majdak P, Laback B. Channel Interaction and Current Level Affect Across-Electrode Integration of Interaural Time Differences in Bilateral Cochlear-Implant Listeners. J Assoc Res Otolaryngol 2015; 17:55-67. [PMID: 26377826 DOI: 10.1007/s10162-015-0542-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 08/30/2015] [Indexed: 11/26/2022] Open
Abstract
Sensitivity to interaural time differences (ITDs) is important for sound localization. Normal-hearing listeners benefit from across-frequency processing, as seen with improved ITD thresholds when consistent ITD cues are presented over a range of frequency channels compared with when ITD information is only presented in a single frequency channel. This study aimed to clarify whether cochlear-implant (CI) listeners can make use of similar processing when being stimulated with multiple interaural electrode pairs transmitting consistent ITD information. ITD thresholds for unmodulated, 100-pulse-per-second pulse trains were measured in seven bilateral CI listeners using research interfaces. Consistent ITDs were presented at either one or two electrode pairs at different current levels, allowing for comparisons at either constant level per component electrode or equal overall loudness. Different tonotopic distances between the pairs were tested in order to clarify the potential influence of channel interaction. Comparison of ITD thresholds between double pairs and the respective single pairs revealed systematic effects of tonotopic separation and current level. At constant levels, performance with double-pair stimulation improved compared with single-pair stimulation but only for large tonotopic separation. Comparisons at equal overall loudness revealed no benefit from presenting ITD information at two electrode pairs for any tonotopic spacing. Irrespective of electrode-pair configuration, ITD sensitivity improved with increasing current level. Hence, the improved ITD sensitivity for double pairs found for a large tonotopic separation and constant current levels seems to be due to increased loudness. The overall data suggest that CI listeners can benefit from combining consistent ITD information across multiple electrodes, provided sufficient stimulus levels and that stimulating electrode pairs are widely spaced.
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Affiliation(s)
- Katharina Egger
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, 1040, Vienna, Austria.
| | - Piotr Majdak
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, 1040, Vienna, Austria.
| | - Bernhard Laback
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, 1040, Vienna, Austria.
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Salminen NH, Altoè A, Takanen M, Santala O, Pulkki V. Human cortical sensitivity to interaural time difference in high-frequency sounds. Hear Res 2015; 323:99-106. [PMID: 25668126 DOI: 10.1016/j.heares.2015.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/22/2015] [Accepted: 01/27/2015] [Indexed: 11/18/2022]
Abstract
Human sound source localization relies on various acoustical cues one of the most important being the interaural time difference (ITD). ITD is best detected in the fine structure of low-frequency sounds but it may also contribute to spatial hearing at higher frequencies if extracted from the sound envelope. The human brain mechanisms related to this envelope ITD cue remain unexplored. Here, we tested the sensitivity of the human auditory cortex to envelope ITD in magnetoencephalography (MEG) recordings. We found two types of sensitivity to envelope ITD. First, the amplitude of the auditory cortical N1m response was smaller for zero envelope ITD than for long envelope ITDs corresponding to the sound being in opposite phase in the two ears. Second, the N1m response amplitude showed ITD-specific adaptation for both fine-structure and for envelope ITD. The auditory cortical sensitivity was weaker for envelope ITD in high-frequency sounds than for fine-structure ITD in low-frequency sounds but occurred within a range of ITDs that are encountered in natural conditions. Finally, the participants were briefly tested for their behavioral ability to detect envelope ITD. Interestingly, we found a correlation between the behavioral performance and the neural sensitivity to envelope ITD. In conclusion, our findings show that the human auditory cortex is sensitive to ITD in the envelope of high-frequency sounds and this sensitivity may have behavioral relevance.
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Affiliation(s)
- Nelli H Salminen
- Brain and Mind Laboratory, Department of Biomedical Engineering and Computational Science, Aalto University School of Science, P.O. Box 12200, FI-00076 Aalto, Finland; MEG Core, Aalto NeuroImaging, Aalto University School of Science, Finland.
| | - Alessandro Altoè
- Department of Signal Processing and Acoustics, Aalto University School of Electrical Engineering, P.O. Box 13000, FI-00076 Aalto, Finland
| | - Marko Takanen
- Department of Signal Processing and Acoustics, Aalto University School of Electrical Engineering, P.O. Box 13000, FI-00076 Aalto, Finland
| | - Olli Santala
- Department of Signal Processing and Acoustics, Aalto University School of Electrical Engineering, P.O. Box 13000, FI-00076 Aalto, Finland
| | - Ville Pulkki
- Department of Signal Processing and Acoustics, Aalto University School of Electrical Engineering, P.O. Box 13000, FI-00076 Aalto, Finland
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Dietz M, Klein-Hennig M, Hohmann V. The influence of pause, attack, and decay duration of the ongoing envelope on sound lateralization. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 137:EL137-43. [PMID: 25698041 DOI: 10.1121/1.4905891] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Klein-Hennig et al. [J. Acoust. Soc. Am. 129, 3856-3872 (2011)] introduced a class of high-frequency stimuli for which the envelope shape can be altered by independently varying the attack, hold, decay, and pause durations. These stimuli, originally employed for testing the shape dependence of human listeners' sensitivity to interaural temporal differences (ITDs) in the ongoing envelope, were used to measure the lateralization produced by fixed interaural disparities. Consistent with the threshold ITD data, a steep attack and a non-zero pause facilitate strong ITD-based lateralization. In contrast, those conditions resulted in the smallest interaural level-based lateralization.
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Affiliation(s)
- Mathias Dietz
- Medizinische Physik and Cluster of Excellence Hearing4all, Universität Oldenburg, D-26111 Oldenburg, Germany , ,
| | - Martin Klein-Hennig
- Medizinische Physik and Cluster of Excellence Hearing4all, Universität Oldenburg, D-26111 Oldenburg, Germany , ,
| | - Volker Hohmann
- Medizinische Physik and Cluster of Excellence Hearing4all, Universität Oldenburg, D-26111 Oldenburg, Germany , ,
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Bernstein LR, Trahiotis C. Sensitivity to envelope-based interaural delays at high frequencies: center frequency affects the envelope rate-limitation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 135:808-816. [PMID: 25234889 PMCID: PMC3985968 DOI: 10.1121/1.4861251] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 05/31/2023]
Abstract
Sensitivity to ongoing interaural temporal disparities (ITDs) was measured using bandpass-filtered pulse trains centered at 4600, 6500, or 9200 Hz. Save for minor differences in the exact center frequencies, those target stimuli were those employed by Majdak and Laback [J. Acoust. Soc. Am. 125, 3903-3913 (2009)]. At each center frequency, threshold ITD was measured for pulse repetition rates ranging from 64 to 609 Hz. The results and quantitative predictions by a cross-correlation-based model indicated that (1) at most pulse repetition rates, threshold ITD increased with center frequency, (2) the cutoff frequency of the putative envelope low-pass filter that determines sensitivity to ITD at high envelope rates appears to be inversely related to center frequency, and (3) both outcomes were accounted for by assuming that, independent of the center frequency, the listeners' decision variable was a constant criterion change in interaural correlation of the stimuli as processed internally. The finding of an inverse relation between center frequency and the envelope rate limitation, while consistent with much prior literature, runs counter to the conclusion reached by Majdak and Laback.
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Affiliation(s)
- Leslie R Bernstein
- Departments of Neuroscience and Surgery (Otolaryngology), University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Constantine Trahiotis
- Departments of Neuroscience and Surgery (Otolaryngology), University of Connecticut Health Center, Farmington, Connecticut 06030
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