Pupil dilation as a function of pitch discrimination difficulty: A replication of Kahneman and Beatty, 1967

In the present paper, we carry out a replication of a seminal paper by Kahneman, D. & Beatty, J. (1967). Perception & Psychophysics, 2(3),101-105 for using pupillometry as an implicit measure of auditory processing load, specifically, non-verbal auditory processing. While numerous papers since have supported the notion that pupillometry is a fairly reliable index of processing load in general  (Zekveld, A. A., Koelewijn, T., and Kramer, S. E. (2018). Trends in Hearing, 22,1-25; Winn, M. B., Wendt, D., Koelewijn, T., and Kuchinsky, S. E. (2018). Trends in Hearing, 22,1-32), they typically have relied on memory recall, and/or more sophisticated cognitive tasks such as language comprehension or split attention. Kahneman and Beatty's paper, despite that it was published more than 50 years ago, continues to be the primary citation to support the claim that pupillometry is a reliable index of task difficulty for a simple non-verbal pitch discrimination task therefore giving us an implicit measure for listening effort (e.g.,Kramer, S. E., Lorens, A., Coninx, F., Zekveld, A. A., Piotrowska, A., & Skarzynski, H. (2013). Language and Cognitive Processes, 28(4),426-442; Schlemmer, K. B., Kulke, F., Kuchinke, L., & Van Der Meer, E. (2005). Psychophysiology, 42(4),465-472; Lisi, M., Bonato, M., and Zorzi, M. (2015). Biological Psychology, 112,39-45). This type of task takes very little explicit memory, is non-verbal, and relies heavily on more low-level, automatic perceptual processing. Using two different replication studies, one exact, and one modified, we only replicated the main result in the modified replication. The true replication failed to replicate on all nine statistical tests. Overall, our findings suggest that pupil dilation can be used as an implicit measure of task difficulty for a simple, non-semantic, auditory task, however, the robustness of the effect appears relatively weak in comparison with the original study, and the amount of variation across participants much greater.

Involvement of the superior colliculi in crossmodal correspondences

There is an increasing body of evidence suggesting that there are low-level perceptual processes involved in crossmodal correspondences. In this study, we investigate the involvement of the superior colliculi in three basic crossmodal correspondences: elevation/pitch, lightness/pitch, and size/pitch. Using a psychophysical design, we modulate visual input to the superior colliculus to test whether the superior colliculus is required for behavioural crossmodal congruency effects to manifest in an unspeeded multisensory discrimination task. In the elevation/pitch task, superior colliculus involvement is required for a behavioural elevation/pitch congruency effect to manifest in the task. In the lightness/pitch and size/pitch task, we observed a behavioural elevation/pitch congruency effect regardless of superior colliculus involvement. These results suggest that the elevation/pitch correspondence may be processed differently to other low-level crossmodal correspondences. The implications of a distributed model of crossmodal correspondence processing in the brain are discussed.

Auditory cortex and beyond: Deficits in congenital amusia

Congenital amusia is a neuro-developmental disorder of music perception and production, with the observed deficits contrasting with the sophisticated music processing reported for the general population. Musical deficits within amusia have been hypothesized to arise from altered pitch processing, with impairments in pitch discrimination and, notably, short-term memory. We here review research investigating its behavioral and neural correlates, in particular the impairments at encoding, retention, and recollection of pitch information, as well as how these impairments extend to the processing of pitch cues in speech and emotion. The impairments have been related to altered brain responses in a distributed fronto-temporal network, which can be observed also at rest. Neuroimaging studies revealed changes in connectivity patterns within this network and beyond, shedding light on the brain dynamics underlying auditory cognition. Interestingly, some studies revealed spared implicit pitch processing in congenital amusia, showing the power of implicit cognition in the music domain. Building on these findings, together with audiovisual integration and other beneficial mechanisms, we outline perspectives for training and rehabilitation and the future directions of this research domain.

Electrophysiological and Psychophysical Measures of Temporal Pitch Sensitivity in Normal-hearing Listeners

To obtain combined behavioural and electrophysiological measures of pitch perception, we presented harmonic complexes, bandpass filtered to contain only high-numbered harmonics, to normal-hearing listeners. These stimuli resemble bandlimited pulse trains and convey pitch using a purely temporal code. A core set of conditions consisted of six stimuli with baseline pulse rates of 94, 188 and 280 pps, filtered into a HIGH (3365-4755 Hz) or VHIGH (7800-10,800 Hz) region, alternating with a 36% higher pulse rate. Brainstem and cortical processing were measured using the frequency following response (FFR) and auditory change complex (ACC), respectively. Behavioural rate change difference limens (DLs) were measured by requiring participants to discriminate between a stimulus that changed rate twice (up-down or down-up) during its 750-ms presentation from a constant-rate pulse train. FFRs revealed robust brainstem phase locking whose amplitude decreased with increasing rate. Moderate-sized but reliable ACCs were obtained in response to changes in purely temporal pitch and, like the psychophysical DLs, did not depend consistently on the direction of rate change or on the pulse rate for baseline rates between 94 and 280 pps. ACCs were larger and DLs lower for stimuli in the HIGH than in the VHGH region. We argue that the ACC may be a useful surrogate for behavioural measures of rate discrimination, both for normal-hearing listeners and for cochlear-implant users. We also showed that rate DLs increased markedly when the baseline rate was reduced to 48 pps, and compared the behavioural and electrophysiological findings to recent cat data obtained with similar stimuli and methods.

Deep neural network models reveal interplay of peripheral coding and stimulus statistics in pitch perception

Perception is thought to be shaped by the environments for which organisms are optimized. These influences are difficult to test in biological organisms but may be revealed by machine perceptual systems optimized under different conditions. We investigated environmental and physiological influences on pitch perception, whose properties are commonly linked to peripheral neural coding limits. We first trained artificial neural networks to estimate fundamental frequency from biologically faithful cochlear representations of natural sounds. The best-performing networks replicated many characteristics of human pitch judgments. To probe the origins of these characteristics, we then optimized networks given altered cochleae or sound statistics. Human-like behavior emerged only when cochleae had high temporal fidelity and when models were optimized for naturalistic sounds. The results suggest pitch perception is critically shaped by the constraints of natural environments in addition to those of the cochlea, illustrating the use of artificial neural networks to reveal underpinnings of behavior.

A new approach to measuring absolute pitch on a psychometric theory of isolated pitch perception: Is it disentangling specific groups or capturing a continuous ability?

Absolute Pitch (AP) is commonly defined as a rare ability that allows an individual to identify any pitch by name. Most researchers use classificatory tests for AP which tracks the number of isolated correct answers. However, each researcher chooses their own procedure for what should be considered correct or incorrect in measuring this ability. Consequently, it is impossible to evaluate comparatively how the stimuli and criteria classify individuals in the same way. We thus adopted a psychometric perspective, approaching AP as a latent trait. Via the Latent Variable Model, we evaluated the consistency and validity for a measure to test for AP ability. A total of 783 undergraduate music students participated in the test. The test battery comprised 10 isolated pitches. All collected data were analyzed with two different rating criteria (perfect and imperfect) under three Latent Variable Model approaches: continuous (Item Response Theory with two and three parameters), categorical (Latent Class Analysis), and the Hybrid model. According to model fit information indices, the perfect approach (only exact pitch responses as correct) measurement model had a better fit under the trait (continuous) specification. This contradicts the usual assumption of a division between AP and non-AP possessors. Alternatively, the categorical solution for the two classes demonstrated the best solution for the imperfect approach (exact pitch responses and semitone deviations considered as correct).

Revisiting discrete versus continuous models of human behavior: The case of absolute pitch

Many human behaviors are discussed in terms of discrete categories. Quantizing behavior in this fashion may provide important traction for understanding the complexities of human experience, but it also may bias understanding of phenomena and associated mechanisms. One example of this is absolute pitch (AP), which is often treated as a discrete trait that is either present or absent (i.e., with easily identifiable near-perfect "genuine" AP possessors and at-chance non-AP possessors) despite emerging evidence that pitch-labeling ability is not all-or-nothing. We used a large-scale online assessment to test the discrete model of AP, specifically by measuring how intermediate performers related to the typically defined "non-AP" and "genuine AP" populations. Consistent with prior research, individuals who performed at-chance (non-AP) reported beginning musical instruction much later than the near-perfect AP participants, and the highest performers were more likely to speak a tonal language than were the lowest performers (though this effect was not as statistically robust as one would expect from prior research). Critically, however, these developmental factors did not differentiate the near-perfect AP performers from the intermediate AP performers. Gaussian mixture modeling supported the existence of two performance distributions-the first distribution encompassed both the intermediate and near-perfect AP possessors, whereas the second distribution encompassed only the at-chance participants. Overall, these results provide support for conceptualizing intermediate levels of pitch-labeling ability along the same continuum as genuine AP-level pitch labeling ability-in other words, a continuous distribution of AP skill among all above-chance performers rather than discrete categories of ability. Expanding the inclusion criteria for AP makes it possible to test hypotheses about the mechanisms that underlie this ability and relate this ability to more general cognitive mechanisms involved in other abilities.

Perceptual inference is impaired in individuals with ASD and intact in individuals who have lost the autism diagnosis

Beyond the symptoms which characterize their diagnoses, individuals with autism spectrum disorder (ASD) show enhanced performance in simple perceptual discrimination tasks. Often attributed to superior sensory sensitivities, enhanced performance may also reflect a weaker bias towards previously perceived stimuli. This study probes perceptual inference in a group of individuals who have lost the autism diagnosis (LAD); that is, they were diagnosed with ASD in early childhood but have no current ASD symptoms. Groups of LAD, current ASD, and typically developing (TD) participants completed an auditory discrimination task. Individuals with TD showed a bias towards previously perceived stimuli-a perceptual process called "contraction bias"; that is, their representation of a given tone was contracted towards the preceding trial stimulus in a manner that is Bayesian optimal. Similarly, individuals in the LAD group showed a contraction bias. In contrast, individuals with current ASD showed a weaker contraction bias, suggesting reduced perceptual inferencing. These findings suggest that changes that characterize LAD extend beyond the social and communicative symptoms of ASD, impacting perceptual domains. Measuring perceptual processing earlier in development in ASD will tap the causality between changes in perceptual and symptomatological domains. Further, the characterization of perceptual inference could reveal meaningful individual differences in complex high-level behaviors.

Effects of Discrimination Task Difficulty on N1 and P2 Components of Late Auditory Evoked Potential

The present study investigated the question of whether, in healthy young listeners, increases in discrimination task difficulty will alter the amplitude of either the N1 or P2 components of the late auditory evoked potential (LAEP). Using a stimulus oddball procedure, listeners discriminated changes in the frequency of ongoing tonal stimuli. On different test runs, task difficulty was manipulated by decreasing the size of the frequency differences and/or adding competing speech babble to the nontest ear. Both stimulus procedures produced significant decreases in P2 amplitude but had no effects on N1 amplitudes. This finding of selective effects on later rather than earlier occurring components of the LAEP provides objective evidence that some forms of auditory processing are mediated at more central levels of the system.

Enhanced Pitch Discrimination for Cochlear Implant Users with a New Haptic Neuroprosthetic

The cochlear implant (CI) is the most widely used neuroprosthesis, recovering hearing for more than half a million severely-to-profoundly hearing-impaired people. However, CIs still have significant limitations, with users having severely impaired pitch perception. Pitch is critical to speech understanding (particularly in noise), to separating different sounds in complex acoustic environments, and to music enjoyment. In recent decades, researchers have attempted to overcome shortcomings in CIs by improving implant technology and surgical techniques, but with limited success. In the current study, we take a new approach of providing missing pitch information through haptic stimulation on the forearm, using our new mosaicOne_B device. The mosaicOne_B extracts pitch information in real-time and presents it via 12 motors that are arranged in ascending pitch along the forearm, with each motor representing a different pitch. In normal-hearing subjects listening to CI simulated audio, we showed that participants were able to discriminate pitch differences at a similar performance level to that achieved by normal-hearing listeners. Furthermore, the device was shown to be highly robust to background noise. This enhanced pitch discrimination has the potential to significantly improve music perception, speech recognition, and speech prosody perception in CI users.

How musical experience affects tone perception efficiency by musicians of tonal and non-tonal speakers?

Purpose

To investigate if, regardless of language background (tonal or non-tonal), musicians may show stronger CP than non-musicians; To examine if native speakers of English (English or non-tonal musicians henceforth) or Mandarin Chinese (Mandarin or tonal musicians henceforth) can better accommodate multiple functions of the same acoustic cue and if musicians’ sensitivity to pitch of lexical tones comes at the cost of slower processing.

Method

English and Mandarin Musicians and non-musicians performed a categorical identification and a discrimination task on rising and falling continua of fundamental frequency on two vowels with 9 duration values.

Results

Non-tonal musicians exhibited significantly stronger categorical perception of pitch contour than non-tonal non-musicians. However, tonal musicians did not consistently perceive the two types of pitch directions more categorically than tonal non-musicians. Both tonal and non-tonal musicians also benefited more from increasing stimulus duration in processing pitch changes than non-musicians and they generally require less time for pitch processing. Musicians were also more sensitive to intrinsic F0 in pitch perception and differences of pitch types.

Conclusion

The effect of musical training strengthens categorical perception more consistently in non-tonal speakers than tonal speakers. Overall, musicians benefit more from increased stimulus duration, due perhaps to their greater sensitivity to temporal information, thus allowing them to be better at forming a more robust auditory representation and matching sounds to internalized memory templates. Musicians also attended more to acoustic details such as intrinsic F0 and pitch types in pitch processing, and yet, overall, their categorization of pitch was not compromised by traces of these acoustic details from their auditory short-term working memory. These findings may lead to a better understanding of pitch perception deficits in special populations, particularly among individuals diagnosed with autism spectrum disorder (ASD).

Short-term memory of temporal information revisited

Previous studies provided diverging evidence regarding modality specificity of temporal information in short-term memory. Some authors reported modality-specific interference effects on visual and auditory duration discrimination, whereas others observed crossmodal interference effects. One reason for these diverging results could be different trade-offs between the temporal discrimination task and the interference task in these studies. Therefore, this study re-examined these effects with interference tasks (speeded color/pitch change discrimination) that were especially suited to assess potential trade-offs between the primary and the secondary tasks. The results showed that the auditory interference task selectively impaired discrimination performance for auditory durations, whereas the visual interference task proved to be inefficient as interference task. The present results agree best with an account that suggests a modality-specific representation of temporal information in short-term memory.

Relationships between vocal pitch perception and production: a developmental perspective

The purpose of this study was to examine the relationships between vocal pitch discrimination abilities and vocal responses to auditory pitch-shifts. Twenty children (6.6-11.7 years) and twenty adults (18-28 years) completed a listening task to determine auditory discrimination abilities to vocal fundamental frequency (fo) as well as two vocalization tasks in which their perceived fo was modulated in real-time. These pitch-shifts were either unexpected, providing information on auditory feedback control, or sustained, providing information on sensorimotor adaptation. Children were subdivided into two groups based on their auditory pitch discrimination abilities; children within two standard deviations of the adult group were classified as having adult-like discrimination abilities (N = 11), whereas children outside of this range were classified as having less sensitive discrimination abilities than adults (N = 9). Children with less sensitive auditory pitch discrimination abilities had significantly larger vocal response magnitudes to unexpected pitch-shifts and significantly smaller vocal response magnitudes to sustained pitch-shifts. Children with less sensitive auditory pitch discrimination abilities may rely more on auditory feedback and thus may be less adept at updating their stored motor programs.

Developmental Effects in Children's Ability to Benefit From F0 Differences Between Target and Masker Speech

OBJECTIVES

The objectives of this study were to (1) evaluate the extent to which school-age children benefit from fundamental frequency (F0) differences between target words and competing two-talker speech, and (2) assess whether this benefit changes with age. It was predicted that while children would be more susceptible to speech-in-speech masking compared to adults, they would benefit from differences in F0 between target and masker speech. A second experiment was conducted to evaluate the relationship between frequency discrimination thresholds and the ability to benefit from target/masker differences in F0.

DESIGN

Listeners were children (5 to 15 years) and adults (20 to 36 years) with normal hearing. In the first experiment, speech reception thresholds (SRTs) for disyllabic words were measured in a continuous, 60-dB SPL two-talker speech masker. The same male talker produced both the target and masker speech (average F0 = 120 Hz). The level of the target words was adaptively varied to estimate the level associated with 71% correct identification. The procedure was a four-alternative forced-choice with a picture-pointing response. Target words either had the same mean F0 as the masker or it was shifted up by 3, 6, or 9 semitones. To determine the benefit of target/masker F0 separation on word recognition, masking release was computed by subtracting thresholds in each shifted-F0 condition from the threshold in the unshifted-F0 condition. In the second experiment, frequency discrimination thresholds were collected for a subset of listeners to determine whether sensitivity to F0 differences would be predictive of SRTs. The standard was the syllable /ba/ with an F0 of 250 Hz; the target stimuli had a higher F0. Discrimination thresholds were measured using a three-alternative, three-interval forced choice procedure.

RESULTS

Younger children (5 to 12 years) had significantly poorer SRTs than older children (13 to 15 years) and adults in the unshifted-F0 condition. The benefit of F0 separations generally increased with increasing child age and magnitude of target/masker F0 separation. For 5- to 7-year-olds, there was a small benefit of F0 separation in the 9-semitone condition only. For 8- to 12-year-olds, there was a benefit from both 6- and 9-semitone separations, but to a lesser degree than what was observed for older children (13 to 15 years) and adults, who showed a substantial benefit in the 6- and 9-semitone conditions. Examination of individual data found that children younger than 7 years of age did not benefit from any of the F0 separations tested. Results for the frequency discrimination task indicated that, while there was a trend for improved thresholds with increasing age, these thresholds were not predictive of the ability to use F0 differences in the speech-in-speech recognition task after controlling for age.

CONCLUSIONS

The overall pattern of results suggests that children's ability to benefit from F0 differences in speech-in-speech recognition follows a prolonged developmental trajectory. Younger children are less able to capitalize on differences in F0 between target and masker speech. The extent to which individual children benefitted from target/masker F0 differences was not associated with their frequency discrimination thresholds.

Reading fluency and pitch discrimination abilities in children with learning disabilities

BACKGROUND

Pitch perception and pitch matching may link to individual reading skills.

OBJECTIVE

In this study, we examined pitch perception and pitch matching tasks in children with learning disabilities to determine whether there was any connection between these tests and the reading fluency in these children.

METHOD

The study used different types of pitch discrimination tests and reading fluency tests to compare the two groups.

RESULTS

Results indicated that the accuracy of pitch discrimination and reading fluency was significantly different in these children with learning disabilities relative to typically developing children. This study also indicated that they exhibit impaired pitch matching, which linked to their reading skills.

CONCLUSION

The results indicate that processing and production of speech may be impacted by individuals' musical pitch perception and matching ability. The results may also give us a piece of evidence that we need further research on how these deficits in musical pitch perception affect our speech and language production in children and adults.

The Relationship Between Speech Perceptual Discrimination and Speech Production in Parkinson's Disease

Purpose We recently demonstrated that individuals with Parkinson's disease (PD) respond differentially to specific altered auditory feedback parameters during speech production. Participants with PD respond more robustly to pitch and less robustly to formant manipulations compared to control participants. In this study, we investigated whether differences in perceptual processing may in part underlie these compensatory differences in speech production. Methods Pitch and formant feedback manipulations were presented under 2 conditions: production and listening. In the production condition, 15 participants with PD and 15 age- and gender-matched healthy control participants judged whether their own speech output was manipulated in real time. During the listening task, participants judged whether paired tokens of their previously recorded speech samples were the same or different. Results Under listening, 1st formant manipulation discrimination was significantly reduced for the PD group compared to the control group. There was a trend toward better discrimination of pitch in the PD group, but the group difference was not significant. Under the production condition, the ability of participants with PD to identify pitch manipulations was greater than that of the controls. Conclusion The findings suggest perceptual processing differences associated with acoustic parameters of fundamental frequency and 1st formant perturbations in PD. These findings extend our previous results, indicating that different patterns of compensation to pitch and 1st formant shifts may reflect a combination of sensory and motor mechanisms that are differentially influenced by basal ganglia dysfunction.

Vowel and Tone Identification for Mandarin Congenital Amusics: Effects of Vowel Type and Semantic Content

Purpose This study aimed to explore the effects of Mandarin congenital amusia with or without lexical tone deficit (i.e., tone agnosia and pure amusia) on Mandarin vowel and tone identification in different types of vowels (e.g., monophthong, diphthongs, and triphthongs) embedded in consonant-vowel contexts with and without semantic content. Method Thirteen pure amusics (i.e., amusics with normal lexical processing), 5 tone agnosics (i.e., with lexical tone deficit), and 12 controls were screened with Montreal Battery of Evaluation of Amusia and lexical tone tests (Nan et al., 2010; Peretz et al., 2003). Vowel-plus-tone identification tasks with the factors of vowel type and syllables with and without semantic content (e.g., real and nonsense words) were examined among the 3 groups, and identification scores were calculated in 3 formats: vowel-plus-tone identification, vowel identification, and tone identification. Results Tone agnosics showed significantly poorer performances on identifications of vowel, tone, and vowel plus tone across monophthongs, diphthongs, and triphthongs in both real and nonsense words compared to pure amusics and controls. Their deficits were similar across the 3 types of vowels, while the deficit on vowel-plus-tone identification was more severe in nonsense words than in real words. On the other hand, pure amusics performed similarly with controls across all these conditions. Conclusions Tone agnosia might affect both musical pitch and phonological processing, resulting in deficits in lexical tone and vowel perception. On the contrary, pure amusics's effect is primarily on musical pitch perception but not on lexical tone or phonemic deficit. Vowel type did not affect speech deficits for tone agnosics, while they relied more on semantic content as a compensation.

Absolute pitch can be learned by some adults

Absolute pitch (AP), the rare ability to name any musical note without the aid of a reference note, is thought to depend on an early critical period of development. Although recent research has shown that adults can improve AP performance in a single training session, the best learners still did not achieve note classification levels comparable to performance of a typical, "genuine" AP possessor. Here, we demonstrate that these "genuine" levels of AP performance can be achieved within eight weeks of training for at least some adults, with the best learner passing all measures of AP ability after training and retaining this knowledge for at least four months after training. Alternative explanations of these positive results, such as improving accuracy through adopting a slower, relative pitch strategy, are not supported based on joint analyses of response time and accuracy. The results also did not appear to be driven by extreme familiarity with a single instrument or octave range, as the post-training AP assessments used eight different timbres and spanned over seven octaves. Yet, it is also important to note that a majority of the participants only exhibited modest improvements in performance, suggesting that adult AP learning is difficult and that near-perfect levels of AP may only be achievable by subset of adults. Overall, these results demonstrate that explicit perceptual training in some adults can lead to AP performance that is behaviorally indistinguishable from AP that manifests within a critical period of development. Implications for theories of AP acquisition are discussed.

Impact of Nonmodal Phonation on Estimates of Subglottal Pressure From Neck-Surface Acceleration in Healthy Speakers

Purpose The purpose of this study was to evaluate the effects of nonmodal phonation on estimates of subglottal pressure (Ps) derived from the magnitude of a neck-surface accelerometer (ACC) signal and to confirm previous findings regarding the impact of vowel contexts and pitch levels in a larger cohort of participants. Method Twenty-six vocally healthy participants (18 women, 8 men) were asked to produce a series of p-vowel syllables with descending loudness in 3 vowel contexts (/a/, /i/, and /u/), 3 pitch levels (comfortable, high, and low), and 4 elicited phonatory conditions (modal, breathy, strained, and rough). Estimates of Ps for each vowel segment were obtained by averaging the intraoral air pressure plateau before and after each segment. The root-mean-square magnitude of the neck-surface ACC signal was computed for each vowel segment. Three linear mixed-effects models were used to statistically assess the effects of vowel, pitch, and phonatory condition on the linear relationship (slope and intercept) between Ps and ACC signal magnitude. Results Results demonstrated statistically significant linear relationships between ACC signal magnitude and Ps within participants but with increased intercepts for the nonmodal phonatory conditions; slopes were affected to a lesser extent. Vowel and pitch contexts did not significantly affect the linear relationship between ACC signal magnitude and Ps. Conclusion The classic linear relationship between ACC signal magnitude and Ps is significantly affected when nonmodal phonation is produced by a speaker. Future work is warranted to further characterize nonmodal phonatory characteristics to improve the ACC-based prediction of Ps during naturalistic speech production.

Relative contribution of pitch and brightness to the auditory kappa effect

Pitch height is known to interfere with temporal judgment. This is the case in the auditory kappa effect in which the relative degree of pitch distance separating two tones extends the perceived duration of the inter-onset interval (IOI). However, pitch variations which result from manipulations of the fundamental frequency of tones are associated with variations of the spectral centroid, which is related to the perceived brightness. The present study aimed at determining the relative contribution of pitch and brightness to the auditory kappa effect. Forty-eight participants performed an AXB paradigm (tone X was shifted to be closer to either tone A or B) in three conditions: the three tones varied in both pitch and brightness (PB condition), pitch varied but brightness was fixed (P condition) or brightness varied but pitch was fixed (B condition). Pitch and brightness were modified by manipulating the fundamental frequency (F0) and the spectral centroid of the tones, respectively. In each condition, the percentage of trials in which the first IOI was perceived as shorter increased as X was closer (in pitch and/or brightness) to A. Furthermore, the magnitude of the effect was larger in PB than in P condition, while it did not differ between PB and B conditions, suggesting that brightness would contribute more than pitch height to the auditory kappa effect. This study provides the first evidence that auditory brightness interferes with duration judgment and highlights the importance to consider jointly the role of pitch height and brightness in future studies on auditory temporal processing.

Longitudinal Development of Wideband Absorbance and Admittance Through Infancy

Purpose The aim of this article was to study the normal longitudinal development of wideband absorbance and admittance measures through infancy. Method Two hundred one infants who passed the newborn hearing screen (automated auditory brainstem response) were tested at birth and then followed up at approximately 6, 12, and 18 months of age. Most infants were of either White (86%) or Asian (11%) descent. At each test session, infants passed tympanometry and distortion product otoacoustic emission tests. High-frequency (1000-Hz) tympanometry was used at birth and 6 months of age, and low-frequency (226-Hz) tympanometry was used at 12 and 18 months of age. Wideband pressure reflectance was also measured at each session and analyzed in terms of absorbance, admittance at the probe tip, and admittance normalized for differences in ear canal area. Multilevel hierarchical models were fitted to the absorbance and admittance data to investigate for effects of age, ear side, gender, ethnicity, and frequency. Results There were considerable age effects on wideband absorbance and admittance measurements over the first 18 months of life. The most dramatic changes occurred between birth and 6 months of age, and there were significant differences between all age groups in the 3000- to 4000-Hz region. There were significant ethnicity effects that were substantial for certain combinations of ethnicity, age, and frequency (e.g., absorbance at 6000 Hz at 12 months of age). Conclusion There are large developmental effects on wideband absorbance and admittance measures through infancy. For absorbance, we recommend separate reference data be used at birth, 6 months of age, and 12-18 months of age. For admittance (both normalized and at the probe tip), we advise using separate normative regions for each age group (neonates and 6, 12, and 18 months).

Pitch Shifting With the Commercially Available Eventide Eclipse: Intended and Unintended Changes to the Speech Signal

Purpose This study details the intended and unintended consequences of pitch shifting with the commercially available Eventide Eclipse. Method Ten vocally healthy participants ( M = 22.0 years; 6 cisgender females, 4 cisgender males) produced a sustained /ɑ/, creating an input signal. This input signal was processed in near real time by the Eventide Eclipse to create an output signal that was either not shifted (0 cents), shifted +100 cents, or shifted -100 cents. Shifts occurred either throughout the entire vocalization or for a 200-ms period after vocal onset. Results Input signals were compared to output signals to examine potential changes. Average pitch-shift magnitudes were within 1 cent of the intended pitch shift. Measured pitch-shift length for intended 200-ms shifts was between 5.9% and 21.7% less than expected, based on the portion of shift selected for measurement. The delay between input and output signals was an average of 11.1 ms. Trials shifted +100 cents had a longer delay than trials shifted -100 or 0 cents. The first 2 formants (F1, F2) shifted in the direction of the pitch shift, with F1 shifting 6.5% and F2 shifting 6.0%. Conclusions The Eventide Eclipse is an accurate pitch-shifting hardware that can be used to explore voice and vocal motor control. The pitch-shifting algorithm shifts all frequencies, resulting in a subsequent change in F1 and F2 during pitch-shifted trials. Researchers using this device should be mindful of stimuli selection to avoid confusion during data interpretation.

Potential cues for the "level discrimination" of a noise band in the presence of flanking bands

To evaluate the ability of a restricted range of auditory-nerve fibers to encode a large perceptual dynamic range, Viemeister [(1983). Science 221, 1206-1208] examined the detection of a change in the level of a high-frequency band of noise flanked by more intense fixed-level noise maskers. Here, stimuli and procedures similar to Viemeister's were used, but random manipulations of level and notch cutoff frequency were included to evaluate predictions of energy-based models. The results indicate that cues other than the change in level per se are available, and suggest the potential contribution of changes in pitch/timbre for this task.

Temporal expectancies affect accuracy in standard-comparison judgments of duration, but neither pitch height, nor timbre, nor loudness

Presenting a stimulus at the most expected point in time should benefit its perceptual processing (Jones, 1976; Large & Jones, 1999). For example, accuracy decreases when comparing the pitch of two tones separated by a sequence of temporally regular distractors if the final tone is shifted away from the expected time (Jones, Moynihan, MacKenzie, & Puente, 2002). However, recent research could not replicate this effect (Bauer, Jaeger, Thorne, Bendixen, & Debener, 2015), so we explored possible explanations. First, we varied the size and probability of timing shifts of the comparison tone in 7 experimental combinations (N = 16 in each). Second, we strengthened temporal expectancies by using a rhythmically rich distractor sequence, either repeating the standard tone at the end of the sequence (N = 26) or not (N = 28). Third, we had listeners compare either the timbre (N = 55) or the loudness (N = 24) instead of pitch. No effects of temporal expectancy (nor interactions with musical training) emerged in these experiments; however, they did occur when participants judged the relative duration of time intervals (N = 38). That is, a temporal expectancy profile was only observable in the context of a temporal task, and did not generalize to other domains. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Auditory frequency discrimination is correlated with linguistic skills, but its training does not improve them or other pitch discrimination tasks

Brain-training, aimed at advancing and improving cognitive and perceptual abilities, is vastly studied because of its immense promise. Yet, there are major controversies regarding its main claim that intensive weeks' training on a single challenging task could improve performance in related untrained tasks. Ample training studies showing transfer were criticized for flawed design. We now explored the impact of perceptual training (auditory frequency discrimination), applying a carefully controlled intensive training experiment. First, we administered a battery of perceptual, linguistic, and cognitive tasks to a large population to determine "near" to "far" tasks according to (pretraining) correlations in performance. This assessment revealed significant correlations between simple pitch discrimination and complex linguistic tasks, including reading and syntactic reasoning. Second, we administered a broad test battery before (and after) training, which included several tasks assessing pitch discrimination, and the linguistic tasks that showed pretraining correlation with auditory frequency discrimination. The test group trained with 2 tone frequency discrimination for 40 sessions. An active control group trained with a working memory (n-back) task for the same duration, and a passive control group was only tested before and after training. Pretraining performance levels were similar in the three groups. Our results were straightforward. No transfer was found to untrained tasks that rely on pith discrimination, or to linguistic tasks that showed pretraining correlation. Mild to marginal transfer was found only to pitch discrimination tasks using almost exactly the trained protocol. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The Production of Question Intonation by Young Adult Cochlear Implant Users: Does Age at Implantation Matter?

Purpose The purpose of this observational study was to investigate the properties of sentence-final prosody in yes/no questions produced by cochlear implant (CI) users in order to determine whether and how the age at CI implantation impacts CI users' production of question intonation later in life. Method We acoustically analyzed recordings from 46 young adult CI users and 10 young adults with normal hearing who read yes/no questions. Of the 46 CI users, 20 had received their CI before the age of 4.0 years (early implantation group), 15 between ages 4.0 and 8.11 years (midimplantation group), and 11 at the age of 9.0 years or later (late implantation group). We assessed the prosodic properties of the produced questions for each implantation group and the normal hearing comparison group (a) by measuring the sentence-final rise in fundamental frequency, (b) by labeling the question-final intonation contour using the Tones and Breaks Index ( Beckman & Ayers, 1994 ; Silverman, Beckman, et al., 1992 ; Veilleux, Shattuck-Hufnagel, & Brugos, 2006 ), and (c) by assessing phrase-final lengthening. Results The fundamental frequency rises produced by all CI users exhibited a smaller magnitude than those produced by the normal hearing comparison group, although the difference between early implanted CI users and the normal hearing group did not reach statistical significance. Early implanted CI users were more comparable in their use of question-final intonation contours to the individuals with typical hearing than to those users with CI implanted later in life. All CI users exhibited significantly less phrase-final lengthening than the normal hearing comparison group, regardless of age at CI implantation. Conclusion The results of this investigation of question intonation produced by CI users suggest that those CI users who were implanted with CI earlier in life produce yes/no question intonation in a manner that is more similar to, albeit not the same as, individuals with normal hearing when compared to the productions of those users with CI implanted after 4.0 years of age.

How Well Can Anaesthetists Discriminate Pulse Oximeter Tones?

The ability of experienced anaesthetists to discern oxygen saturation by listening to the tones of a Datex AS3 pulse oximeter was examined. Five-second samples were recorded using a high fidelity patient simulator and replayed singly and in pairs. Whilst the lower saturations were generally recognized as lower, the perceived range was greatly compressed. Median perceived estimates for 70% saturation was 89%, for 80% was 93% and for 94% was 94%. When comparing pairs of samples, the direction of the difference was correctly discerned by 70% of anaesthetists for differences of 2%, rising to 95% for differences of greater than 8% oxygen saturation. The magnitude of the difference was consistently underestimated. With an actual difference of 20%, the median estimate was 5%. The results indicate that while qualitative estimate changes in oxygen saturation are moderately reliable, quantitative estimation is severely limited by a compromised perceived scale. This may lead to underestimation of the severity if the auditory signal is relied on in isolation. A non-linear (musical) scale may prove more appropriate and should be investigated. Testing experienced anaesthetists demonstrated that most could detect the direction, but not the magnitude of a change in saturation by listening to the change in pitch of a Datex AS3 pulse oximeter tone.

Cortical thickness of Broca's area and right homologue is related to grammar learning aptitude and pitch discrimination proficiency

Aptitude for and proficiency in acquiring new languages varies in the human population but their neural bases are largely unknown. We investigated the influence of cortical thickness on language learning predictors measured by the LLAMA tests and a pitch-change discrimination test. The LLAMA tests are first language-independent assessments of language learning aptitude for vocabulary, phonetic working memory, sound-symbol correspondence (not used in this study), and grammatical inferencing. Pitch perception proficiency is known to predict aptitude for learning new phonology. Results show a correlation between scores in a grammatical meaning-inferencing aptitude test and cortical thickness of Broca's area (r(30) = 0.65, p = 0.0202) and other frontal areas (r(30) = 0.66, p = 0.0137). Further, a correlation was found between proficiency in discriminating pitch-change direction and cortical thickness of the right Broca homologue (r(30) = 0.57, p = 0.0006). However, no correlations were found for aptitude for vocabulary learning or phonetic working memory. Results contribute to locating cortical regions important for language-learning aptitude.

Automatic intonation classification using temporal patterns in utterance-level pitch contour and perceptually motivated pitch transformation

Second language learners of British English (BE) are typically trained for four intonation classes: Glide-up, Glide-down, Dive, and Take-off. Automatic four-way intonation classification could be useful to evaluate a learner's pronunciation. However, such automatic classification is challenging without having manually annotated tones, typically considered in intonation analysis and classification tasks. In this, a three-dimensional feature sequence is proposed representing temporal patterns in the utterance-level f0 contour using a perceptually motivated pitch transformation. Hidden Markov model based classification experiments conducted using a training material for teaching BE intonation demonstrate the benefit of the proposed approach over the baseline scheme considered.

Effects of the relative timing of opposite-polarity pulses on loudness for cochlear implant listeners

The symmetric biphasic pulses used in contemporary cochlear implants (CIs) consist of both cathodic and anodic currents, which may stimulate different sites on spiral ganglion neurons and, potentially, interact with each other. The effect on the order of anodic and cathodic stimulation on loudness at short inter-pulse intervals (IPIs; 0-800 μs) is investigated. Pairs of opposite-polarity pseudomonophasic (PS) pulses were used and the amplitude of each pulse was manipulated independently. In experiment 1 the two PS pulses differed in their current level in order to elicit the same loudness when presented separately. Six users of the Advanced Bionics CI (Valencia, CA) loudness-ranked trains of the pulse pairs using a midpoint-comparison procedure. Stimuli with anodic-leading polarity were louder than those with cathodic-leading polarity for IPIs shorter than 400 μs. This effect was small-about 0.3 dB-but consistent across listeners. When the same procedure was repeated with both PS pulses having the same current level (experiment 2), anodic-leading stimuli were still louder than cathodic-leading stimuli at very short intervals. However, when using symmetric biphasic pulses (experiment 3) the effect disappeared at short intervals and reversed at long intervals. Possible peripheral sources of such polarity interactions are discussed.

Fundamental-frequency discrimination based on temporal-envelope cues: Effects of bandwidth and interference

Both music and speech perception rely on hearing out one pitch in the presence of others. Pitch discrimination of narrowband sounds based only on temporal-envelope cues is rendered nearly impossible by introducing interferers in both normal-hearing listeners and cochlear-implant (CI) users. This study tested whether performance improves in normal-hearing listeners if the target is presented over a broad spectral region. The results indicate that performance is still strongly affected by spectrally remote interferers, despite increases in bandwidth, suggesting that envelope-based pitch is unlikely to allow CI users to perceive pitch when multiple harmonic sounds are presented at once.

Learning for pitch and melody discrimination in congenital amusia

Congenital amusia is currently thought to be a life-long neurogenetic disorder in music perception, impervious to training in pitch or melody discrimination. This study provides an explicit test of whether amusic deficits can be reduced with training. Twenty amusics and 20 matched controls participated in four sessions of psychophysical training involving either pure-tone (500 Hz) pitch discrimination or a control task of lateralization (interaural level differences for bandpass white noise). Pure-tone pitch discrimination at low, medium, and high frequencies (500, 2000, and 8000 Hz) was measured before and after training (pretest and posttest) to determine the specificity of learning. Melody discrimination was also assessed before and after training using the full Montreal Battery of Evaluation of Amusia, the most widely used standardized test to diagnose amusia. Amusics performed more poorly than controls in pitch but not localization discrimination, but both groups improved with practice on the trained stimuli. Learning was broad, occurring across all three frequencies and melody discrimination for all groups, including those who trained on the non-pitch control task. Following training, 11 of 20 amusics no longer met the global diagnostic criteria for amusia. A separate group of untrained controls (n = 20), who also completed melody discrimination and pretest, improved by an equal amount as trained controls on all measures, suggesting that the bulk of learning for the control group occurred very rapidly from the pretest. Thirty-one trained participants (13 amusics) returned one year later to assess long-term maintenance of pitch and melody discrimination. On average, there was no change in performance between posttest and one-year follow-up, demonstrating that improvements on pitch- and melody-related tasks in amusics and controls can be maintained. The findings indicate that amusia is not always a life-long deficit when using the current standard diagnostic criteria.

Mismatch negativity reflects asymmetric pre-attentive harmonic interval discrimination

Objective

Western music is based on intervals; thus, interval discrimination is important for distinguishing the character of melodies or tracking melodies in polyphonic music. In this study the encoding of intervals in simultaneously presented sound is studied.

Study design

In an electrophysiological experiment in 15 normal-hearing non-musicians, major thirds or fifths were presented in a controlled oddball paradigm. Harmonic intervals were created by simultaneously presented sinusoidals with randomized root frequency. Mismatch negativity (MMN) responses were measured with an EEG recording. The discrimination index was calculated in a psychoacoustic experiment.

Results

A clear MMN response was found for the major third but not for the fifth. The neural generators were located within the auditory cortices. Psychoacoustically, no evidence was found that the subjects were able to detect the deviants.

Conclusions

We conclude that pre-attentive discrimination of harmonic interval size is, in principle, possible in listeners without musical training although simultaneous presentation makes it harder to distinguish compared to non-overlapping intervals. Furthermore we see a difference in the response to infrequent dissonant stimuli in consonant standard stimuli compared to the opposite, rare consonant stimuli in dissonant standard stimuli.

The discrimination of voice cues in simulations of bimodal electro-acoustic cochlear-implant hearing

In discriminating speakers' voices, normal-hearing individuals effectively use two vocal characteristics, vocal pitch (related to fundamental frequency, F0) and vocal-tract length (VTL, related to speaker size). Typical cochlear-implant users show poor perception of these cues. However, in implant users with low-frequency residual acoustic hearing, this bimodal electro-acoustic stimulation may provide additional voice-related cues, such as low-numbered harmonics and formants, which could improve F0/VTL perception. In acoustic noise-vocoder simulations, where added low-pass filtered speech simulated residual hearing, a strong bimodal benefit was observed for F0 perception. No bimodal benefit was observed for VTL, which seems to mainly rely on vocoder spectral resolution.

Spectral Ripple Discrimination in Normal-Hearing Infants

OBJECTIVES

Spectral resolution is a correlate of open-set speech understanding in postlingually deaf adults and prelingually deaf children who use cochlear implants (CIs). To apply measures of spectral resolution to assess device efficacy in younger CI users, it is necessary to understand how spectral resolution develops in normal-hearing children. In this study, spectral ripple discrimination (SRD) was used to measure listeners' sensitivity to a shift in phase of the spectral envelope of a broadband noise. Both resolution of peak to peak location (frequency resolution) and peak to trough intensity (across-channel intensity resolution) are required for SRD.

DESIGN

SRD was measured as the highest ripple density (in ripples per octave) for which a listener could discriminate a 90° shift in phase of the sinusoidally-modulated amplitude spectrum. A 2 × 3 between-subjects design was used to assess the effects of age (7-month-old infants versus adults) and ripple peak/trough "depth" (10, 13, and 20 dB) on SRD in normal-hearing listeners (experiment 1). In experiment 2, SRD thresholds in the same age groups were compared using a task in which ripple starting phases were randomized across trials to obscure within-channel intensity cues. In experiment 3, the randomized starting phase method was used to measure SRD as a function of age (3-month-old infants, 7-month-old infants, and young adults) and ripple depth (10 and 20 dB in repeated measures design).

RESULTS

In experiment 1, there was a significant interaction between age and ripple depth. The infant SRDs were significantly poorer than the adult SRDs at 10 and 13 dB ripple depths but adult-like at 20 dB depth. This result is consistent with immature across-channel intensity resolution. In contrast, the trajectory of SRD as a function of depth was steeper for infants than adults suggesting that frequency resolution was better in infants than adults. However, in experiment 2 infant performance was significantly poorer than adults at 20 dB depth suggesting that variability of infants' use of within-channel intensity cues, rather than better frequency resolution, explained the results of experiment 1. In experiment 3, age effects were seen with both groups of infants showing poorer SRD than adults but, unlike experiment 1, no significant interaction between age and depth was seen.

CONCLUSIONS

Measurement of SRD thresholds in individual 3 to 7-month-old infants is feasible. Performance of normal-hearing infants on SRD may be limited by across-channel intensity resolution despite mature frequency resolution. These findings have significant implications for design and stimulus choice for applying SRD for testing infants with CIs. The high degree of variability in infant SRD can be somewhat reduced by obscuring within-channel cues.

Sensorimotor adaptation of voice fundamental frequency in Parkinson's disease

OBJECTIVE

This study examined adaptive responses to auditory perturbation of fundamental frequency (fo) in speakers with Parkinson's disease (PD) and control speakers.

METHOD

Sixteen speakers with PD and nineteen control speakers produced sustained vowels while they received perturbed auditory feedback (i.e., fo shifted upward or downward). Speakers' pitch acuity was quantified using a just-noticeable-difference (JND) paradigm. Twelve listeners provided estimates of the speech intelligibility for speakers with PD.

RESULTS

Fifteen responses from each speaker group for each shift direction were included in analyses. While control speakers generally showed consistent adaptive responses opposing the perturbation, speakers with PD showed no compensation on average, with individual PD speakers showing highly variable responses. In the PD group, the degree of compensation was not significantly correlated with age, disease progression, pitch acuity, or intelligibility.

CONCLUSIONS

These findings indicate reduced adaptation to sustained fo perturbation and higher variability in PD compared to control participants. No significant differences were seen in pitch acuity between groups, suggesting that the fo adaptation deficit in PD is not the result of purely perceptual mechanisms.

SIGNIFICANCE

These results suggest there is an impairment in vocal motor control in PD. Building on these results, contributions can be made to developing targeted voice treatments for PD.

Short Article: Knowing When to Hear Aids What to Hear

Temporal preparation often has been assumed to influence motor stages of information processing. Recent studies, however, challenge this notion and provide evidence for a facilitation of visual processing. The present study was designed to investigate whether perceptual processing in the auditory domain also benefits from temporal preparation. To this end, we employed a pitch discrimination task. In Experiment 1, discrimination performance was clearly improved when participants were temporally prepared. This finding was confirmed in Experiment 2, which ruled out possible influences of short-term memory. The results support the notion that temporal preparation enhances perceptual processing not only in the visual, but also in the auditory, modality.

Haptics in Music: The Effects of Vibrotactile Stimulus in Low Frequency Auditory Difference Detection Tasks

We present an experiment that investigated the effect of vibrotactile stimulation in auditory pitch discrimination tasks. Extra-auditory information was expected to have some influence upon the frequency discrimination of auditory Just Noticeable Difference (JND) detection levels at 160 Hz. To measure this, the potential to correctly identified positive and negative frequency changes for two randomly divided groups was measured and then compared. The first group was given an audio only JND test and the second group was given the same test, but with additional vibrotactile stimulus delivered via a vibrating glove device. The results of the experiment suggest that in musical interactions involving the selection of specific pitches, or the detection of pitch variation, vibrotactile feedback may have some advantageous effect upon a musician's ability to perceive changes when presented in synchrony with auditory stimulus.

Encoding a Melody Using Only Temporal Information for Cochlear-Implant and Normal-Hearing Listeners

One way to provide pitch information to cochlear implant users is through amplitude-modulation rate. It is currently unknown whether amplitude-modulation rate can provide cochlear implant users with pitch information adequate for perceiving melodic information. In the present study, the notes of a song were encoded via amplitude-modulation rate of pulse trains on single electrodes at the apex or middle of long electrode arrays. The melody of the song was either physically correct or modified by compression or expansion. Nine cochlear implant users rated the extent to which the song was out of tune in the different conditions. Cochlear implant users on average did not show sensitivity to melody compression or expansion regardless of place of stimulation. These results were found despite the fact that three of the cochlear implant users showed the expected sensitivity to melody compression and expansion with the same task using acoustic pure tones in a contralateral acoustic ear. Normal-hearing listeners showed an inconsistent and weak effect of melody compression and expansion when the notes of the song were encoded with acoustic pulse rate. The results suggest that amplitude-modulation rate provides insufficient access to melodic information for cochlear-implant and normal-hearing listeners.

Relating approach-to-target and detection tasks in animal psychoacoustics

Psychophysical experiments seek to measure the limits of perception. While straightforward in humans, in animals they are time consuming. Choosing an appropriate task and interpreting measurements can be challenging. We investigated the localization of high-frequency auditory signals in noise using an "approach-to-target" task in ferrets, how task performance should be interpreted in terms of perception, and how the measurements relate to other types of tasks. To establish their general ability to localize, animals were first trained to discriminate broadband noise from 12 locations. Subsequently we tested their ability to discriminate between band-limited targets at 2 or 3 more widely spaced locations, in a continuous background noise. The ability to discriminate between 3 possible locations (-90°, 0°, 90°) of a 10-kHz pure tone decreased gradually over a wide range (>30 dB) of signal-to-noise ratios (SNRs). Location discrimination ability was better for wide band noise targets (0.5 and 2 octave). These results were consistent with localization ability limiting performance for pure tones. Discrimination of pure tones at 2 locations (-90/left, 90/right) was robust at positive SNRs, yielding psychometric functions which fell steeply at negative SNRs. Thresholds for discrimination were similar to previous tone-in-noise thresholds measured in ferrets using a yes/no task. Thus, using an approach-to-target task, sound "localization" in noise can reflect detectability or the ability to localize, depending on the stimulus configuration. Signal-detection-theory-based models were able to account for the results when discriminating between pure tones from 2- and 3-source locations. (PsycINFO Database Record

Adaptation of Central Pitch-Specific Mechanisms

Three previous psychophysical studies have demonstrated that interaural time difference (ITD) coding mechanisms can undergo frequency-specific, selective adaptation. We sought to determine whether this phenomenon extends to the pitch domain, by employing the same psychophysical paradigm as one used previously, but with harmonic tone complexes lacking energy at the fundamental frequency. Ten normal listeners participated in experiment 1. Psychometric functions for ITDs were obtained for harmonic tone complexes with fundamental frequencies of 110 Hz and 185 Hz, before and after selective adaptation with complexes of the same fundamental frequencies lateralised to opposite sides. In experiment 1, each subject was tested twice. On separate days, subjects were tested with 110 Hz and 185 Hz stimuli that were either partially resolvable complexes or unresolvable ones. Both partially resolved and unresolved stimuli supported adaptation, and at both fundamental frequencies. In experiment 2, which employed nine listeners, the adaptor tone complexes were presented in conjunction with a diotic noise background designed to mask difference tones generated by the adaptor stimuli. The use of the masker had little effect on the mean strength of the adaptation effected by the unresolved adaptor stimuli, and only slightly weakened the adaptation effect found with the partially resolved adaptor stimuli. Taken together, these data constitute the first demonstration of selective adaptation exerted on a central mechanism in the pitch domain.

Pitch Processing in Tonal-Language-Speaking Children with Autism: An Event-Related Potential Study

The present study investigated pitch processing in Mandarin-speaking children with autism using event-related potential measures. Two experiments were designed to test how acoustic, phonetic and semantic properties of the stimuli contributed to the neural responses for pitch change detection and involuntary attentional orienting. In comparison with age-matched (6-12 years) typically developing controls (16 participants in Experiment 1, 18 in Experiment 2), children with autism (18 participants in Experiment 1, 16 in Experiment 2) showed enhanced neural discriminatory sensitivity in the nonspeech conditions but not for speech stimuli. The results indicate domain specificity of enhanced pitch processing in autism, which may interfere with lexical tone acquisition and language development for children who speak a tonal language.

Activation in the Right Inferior Parietal Lobule Reflects the Representation of Musical Structure beyond Simple Pitch Discrimination

Pitch discrimination tasks typically engage the superior temporal gyrus and the right inferior frontal gyrus. It is currently unclear whether these regions are equally involved in the processing of incongruous notes in melodies, which requires the representation of musical structure (tonality) in addition to pitch discrimination. To this aim, 14 participants completed two tasks while undergoing functional magnetic resonance imaging, one in which they had to identify a pitch change in a series of non-melodic repeating tones and a second in which they had to identify an incongruous note in a tonal melody. In both tasks, the deviants activated the right superior temporal gyrus. A contrast between deviants in the melodic task and deviants in the non-melodic task (melodic > non-melodic) revealed additional activity in the right inferior parietal lobule. Activation in the inferior parietal lobule likely represents processes related to the maintenance of tonal pitch structure in working memory during pitch discrimination.

Recognition of Frequency Modulated Whistle-Like Sounds by a Bottlenose Dolphin (Tursiops truncatus) and Humans with Transformations in Amplitude, Duration and Frequency

Bottlenose dolphins (Tursiops truncatus) use the frequency contour of whistles produced by conspecifics for individual recognition. Here we tested a bottlenose dolphin's (Tursiops truncatus) ability to recognize frequency modulated whistle-like sounds using a three alternative matching-to-sample paradigm. The dolphin was first trained to select a specific object (object A) in response to a specific sound (sound A) for a total of three object-sound associations. The sounds were then transformed by amplitude, duration, or frequency transposition while still preserving the frequency contour of each sound. For comparison purposes, 30 human participants completed an identical task with the same sounds, objects, and training procedure. The dolphin's ability to correctly match objects to sounds was robust to changes in amplitude with only a minor decrement in performance for short durations. The dolphin failed to recognize sounds that were frequency transposed by plus or minus ½ octaves. Human participants demonstrated robust recognition with all acoustic transformations. The results indicate that this dolphin's acoustic recognition of whistle-like sounds was constrained by absolute pitch. Unlike human speech, which varies considerably in average frequency, signature whistles are relatively stable in frequency, which may have selected for a whistle recognition system invariant to frequency transposition.

Varying irrelevant phonetic features hinders learning of the feature being trained

Learning to distinguish nonnative words that differ in a critical phonetic feature can be difficult. Speech training studies typically employ methods that explicitly direct the learner's attention to the relevant nonnative feature to be learned. However, studies on vision have demonstrated that perceptual learning may occur implicitly, by exposing learners to stimulus features, even if they are irrelevant to the task, and it has recently been suggested that this task-irrelevant perceptual learning framework also applies to speech. In this study, subjects took part in a seven-day training regimen to learn to distinguish one of two nonnative features, namely, voice onset time or lexical tone, using explicit training methods consistent with most speech training studies. Critically, half of the subjects were exposed to stimuli that varied not only in the relevant feature, but in the irrelevant feature as well. The results showed that subjects who were trained with stimuli that varied in the relevant feature and held the irrelevant feature constant achieved the best learning outcomes. Varying both features hindered learning and generalization to new stimuli.

Pitch and spectral resolution: A systematic comparison of bottom-up cues for top-down repair of degraded speech

The brain is capable of restoring missing parts of speech, a top-down repair mechanism that enhances speech understanding in noisy environments. This enhancement can be quantified using the phonemic restoration paradigm, i.e., the improvement in intelligibility when silent interruptions of interrupted speech are filled with noise. Benefit from top-down repair of speech differs between cochlear implant (CI) users and normal-hearing (NH) listeners. This difference could be due to poorer spectral resolution and/or weaker pitch cues inherent to CI transmitted speech. In CIs, those two degradations cannot be teased apart because spectral degradation leads to weaker pitch representation. A vocoding method was developed to evaluate independently the roles of pitch and spectral resolution for restoration in NH individuals. Sentences were resynthesized with different spectral resolutions and with either retaining the original pitch cues or discarding them all. The addition of pitch significantly improved restoration only at six-bands spectral resolution. However, overall intelligibility of interrupted speech was improved both with the addition of pitch and with the increase in spectral resolution. This improvement may be due to better discrimination of speech segments from the filler noise, better grouping of speech segments together, and/or better bottom-up cues available in the speech segments.

Vocal imitations of basic auditory features

Describing complex sounds with words is a difficult task. In fact, previous studies have shown that vocal imitations of sounds are more effective than verbal descriptions [Lemaitre and Rocchesso (2014). J. Acoust. Soc. Am. 135, 862-873]. The current study investigated how vocal imitations of sounds enable their recognition by studying how two expert and two lay participants reproduced four basic auditory features: pitch, tempo, sharpness, and onset. It used 4 sets of 16 referent sounds (modulated narrowband noises and pure tones), based on 1 feature or crossing 2 of the 4 features. Dissimilarity rating experiments and multidimensional scaling analyses confirmed that listeners could accurately perceive the four features composing the four sets of referent sounds. The four participants recorded vocal imitations of the four sets of sounds. Analyses identified three strategies: (1) Vocal imitations of pitch and tempo reproduced faithfully the absolute value of the feature; (2) Vocal imitations of sharpness transposed the feature into the participants' registers; (3) Vocal imitations of onsets categorized the continuum of onset values into two discrete morphological profiles. Overall, these results highlight that vocal imitations do not simply mimic the referent sounds, but seek to emphasize the characteristic features of the referent sounds within the constraints of human vocal production.

Mandarin speech-in-noise and tone recognition using vocoder simulations of the temporal limits encoder for cochlear implants

Temporal envelope-based signal processing strategies are widely used in cochlear-implant (CI) systems. It is well recognized that the inability to convey temporal fine structure (TFS) in the stimuli limits CI users' performance, but it is still unclear how to effectively deliver the TFS. A strategy known as the temporal limits encoder (TLE), which employs an approach to derive the amplitude modulator to generate the stimuli coded in an interleaved-sampling strategy, has recently been proposed. The TLE modulator contains information related to the original temporal envelope and a slow-varying TFS from the band signal. In this paper, theoretical analyses are presented to demonstrate the superiority of TLE compared with two existing strategies, the clinically available continuous-interleaved-sampling (CIS) strategy and the experimental harmonic-single-sideband-encoder strategy. Perceptual experiments with vocoder simulations in normal-hearing listeners are conducted to compare the performance of TLE and CIS on two tasks (i.e., Mandarin speech reception in babble noise and tone recognition in quiet). The performance of the TLE modulator is mostly better than (for most tone-band vocoders) or comparable to (for noise-band vocoders) the CIS modulator on both tasks. This work implies that there is some potential for improving the representation of TFS with CIs by using a TLE strategy.

The effect of presentation level on spectral weights for sentences

Psychophysical data indicate that spectral weights tend to increase with increasing presentation level at high frequencies. The present study examined whether spectral weights for speech perception are similarly affected by presentation level. Stimuli were sentences filtered into five contiguous frequency bands and presented at each of two levels (75 and 95 dB sound pressure level [SPL]). For the highest band (2807-10,000 Hz), normal-hearing listeners' weights were higher for the higher presentation level. Weights for the 95-dB-SPL level resembled those previously estimated for hearing-impaired listeners tested at comparably high levels, suggesting that hearing loss itself may not play a large role in spectral weighting for a sentence recognition task.

Sensitivity to Envelope Interaural Time Differences at High Modulation Rates

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.