Objective assessment of frequency-specific hearing thresholds in babies

Amplitude Modulation Perception and Cortical Evoked Potentials in Children With Listening Difficulties and Their Typically Developing Peers

PURPOSE

Amplitude modulations (AMs) are important for speech intelligibility, and deficits in speech intelligibility are a leading source of impairment in childhood listening difficulties (LiD). The present study aimed to explore the relationships between AM perception and speech-in-noise (SiN) comprehension in children and to determine whether deficits in AM processing contribute to childhood LiD. Evoked responses were used to parse the neural origins of AM processing.

METHOD

Forty-one children with LiD and 44 typically developing children, ages 8-16 years, participated in the study. Behavioral AM depth thresholds were measured at 4 and 40 Hz. SiN tasks included the Listening in Spatialized Noise-Sentences Test (LiSN-S) and a coordinate response measure (CRM)-based task. Evoked responses were obtained during an AM change detection task using alternations between 4 and 40 Hz, including the N1 of the acoustic change complex, auditory steady-state response (ASSR), P300, and a late positive response (late potential [LP]). Maturational effects were explored via age correlations.

RESULTS

Age correlated with 4-Hz AM thresholds, CRM separated talker scores, and N1 amplitude. Age-normed LiSN-S scores obtained without spatial or talker cues correlated with age-corrected 4-Hz AM thresholds and area under the LP curve. CRM separated talker scores correlated with AM thresholds and area under the LP curve. Most behavioral measures of AM perception correlated with the signal-to-noise ratio and phase coherence of the 40-Hz ASSR. AM change response time also correlated with area under the LP curve. Children with LiD exhibited deficits with respect to 4-Hz thresholds, AM change accuracy, and area under the LP curve.

CONCLUSIONS

The observed relationships between AM perception and SiN performance extend the evidence that modulation perception is important for understanding SiN in childhood. In line with this finding, children with LiD demonstrated poorer performance on some measures of AM perception, but their evoked responses implicated a primarily cognitive deficit.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25009103.

Amplitude modulation perception and cortical evoked potentials in children with listening difficulties and their typically-developing peers

Purpose

Amplitude modulations (AM) are important for speech intelligibility, and deficits in speech intelligibility are a leading source of impairment in childhood listening difficulties (LiD). The present study aimed to explore the relationships between AM perception and speech-in-noise (SiN) comprehension in children and to determine whether deficits in AM processing contribute to childhood LiD. Evoked responses were used to parse the neural origin of AM processing.

Method

Forty-one children with LiD and forty-four typically-developing children, ages 8-16 y.o., participated in the study. Behavioral AM depth thresholds were measured at 4 and 40 Hz. SiN tasks included the LiSN-S and a Coordinate Response Measure (CRM)-based task. Evoked responses were obtained during an AM Change detection task using alternations between 4 and 40 Hz, including the N1 of the acoustic change complex, auditory steady-state response (ASSR), P300, and a late positive response (LP). Maturational effects were explored via age correlations.

Results

Age correlated with 4 Hz AM thresholds, CRM Separated Talker scores, and N1 amplitude. Age-normed LiSN-S scores obtained without spatial or talker cues correlated with age-corrected 4 Hz AM thresholds and area under the LP curve. CRM Separated Talker scores correlated with AM thresholds and area under the LP curve. Most behavioral measures of AM perception correlated with the SNR and phase coherence of the 40 Hz ASSR. AM Change RT also correlated with area under the LP curve. Children with LiD exhibited deficits with respect to 4 Hz thresholds, AM Change accuracy, and area under the LP curve.

Conclusions

The observed relationships between AM perception and SiN performance extend the evidence that modulation perception is important for understanding SiN in childhood. In line with this finding, children with LiD demonstrated poorer performance on some measures of AM perception, but their evoked responses implicated a primarily cognitive deficit.

Analysis methods for measuring passive auditory fNIRS responses generated by a block-design paradigm

Significance: Functional near-infrared spectroscopy (fNIRS) is an increasingly popular tool in auditory research, but the range of analysis procedures employed across studies may complicate the interpretation of data. Aim: We aim to assess the impact of different analysis procedures on the morphology, detection, and lateralization of auditory responses in fNIRS. Specifically, we determine whether averaging or generalized linear model (GLM)-based analysis generates different experimental conclusions when applied to a block-protocol design. The impact of parameter selection of GLMs on detecting auditory-evoked responses was also quantified. Approach: 17 listeners were exposed to three commonly employed auditory stimuli: noise, speech, and silence. A block design, comprising sounds of 5 s duration and 10 to 20 s silent intervals, was employed. Results: Both analysis procedures generated similar response morphologies and amplitude estimates, and both indicated that responses to speech were significantly greater than to noise or silence. Neither approach indicated a significant effect of brain hemisphere on responses to speech. Methods to correct for systemic hemodynamic responses using short channels improved detection at the individual level. Conclusions: Consistent with theoretical considerations, simulations, and other experimental domains, GLM and averaging analyses generate the same group-level experimental conclusions. We release this dataset publicly for use in future development and optimization of algorithms.

Auditory steady-state responses during and after a stimulus: Cortical sources, and the influence of attention and musicality

The auditory steady-state response (ASSR) is an oscillatory brain response generated by periodic auditory stimuli and originates mainly from the temporal auditory cortices. Recent data show that while the auditory cortices are indeed strongly activated by the stimulus when it is present (ON ASSR), the anatomical distribution of ASSR sources involves also parietal and frontal cortices, indicating that the ASSR is a more complex phenomenon than previously believed. Furthermore, while the ASSR typically continues to oscillate even after the stimulus has stopped (OFF ASSR), very little is known about the characteristics of the OFF ASSR and how it compares to the ON ASSR. Here, we assessed whether the OFF and ON ASSR powers are modulated by the stimulus properties (i.e. volume and pitch), selective attention, as well as individual musical sophistication. We also investigated the cortical source distribution of the OFF ASSR using a melody tracking task, in which attention was directed between uniquely amplitude-modulated melody streams that differed in pitch. The ON and OFF ASSRs were recorded with magnetoencephalography (MEG) on a group of participants varying from low to high degree of musical sophistication. Our results show that the OFF ASSR is different from the ON ASSR in nearly every aspect. While the ON ASSR was modulated by the stimulus properties and selective attention, the OFF ASSR was not influenced by any of these factors. Furthermore, while the ON ASSR was generated primarily from temporal sources, the OFF ASSR originated mainly from the frontal cortex. These findings challenge the notion that the OFF ASSR is merely a continuation of the ON ASSR. Rather, they suggest that the OFF ASSR is an internally-driven signal that develops from an initial sensory processing state (ON ASSR), with both types of ASSRs clearly differing in cortical representation and character. Furthermore, our results show that the ON ASSR power was enhanced by selective attention at cortical sources within each of the bilateral frontal, temporal, parietal and insular lobes. Finally, the ON ASSR proved sensitive to musicality, demonstrating positive correlations between musical sophistication and ASSR power, as well as with the degree of attentional ASSR modulation at the left and right parietal cortices. Taken together, these results show new aspects of the ASSR response, and demonstrate its usefulness as an effective tool for analysing how selective attention interacts with individual abilities in music perception.

Using ASSR with narrow-band chirps to evaluate hearing in children and adults

PURPOSE

All studies concerning the reliability and threshold prediction of auditory steady-state responses (ASSR) focused on a particular group of patients. The present article evaluates the use of narrow-band, chirp-evoked ASSR for testing hearing in adults and children of all ages and with different types of hearing loss, as well as normal hearing. The aims are: to determine whether there are possible influencing factors, mainly the degree of hearing loss; and to validate the clinical value of using ASSR with chirp-stimuli.

METHODS

This is a retrospective study of 667 patients who had been diagnosed with and treated for hearing loss at our tertiary referral center. The following results were compared: ASSR to pure tone audiometry (PTA); click-ABRs to PTA; and click-ABRs to ASSR. We then calculated mean, median and standard deviation. A regression analysis was used to examine the correlation between: ASSR and click-ABRs; "estimated" audiogram and PTA; click-ABRs and PTA; and ASSR and PTA.

RESULTS

We found significant correlations at all frequencies when comparing ASSR to click-ABRs, click-ABRs to PTA, and ASSR to PTA. Concerning the degree of hearing loss, there were significant differences between the patients with normal hearing and those with moderate-to-profound hearing loss.

CONCLUSION

ASSR with narrow-band chirps are a reliable tool for estimating hearing thresholds in children and adults with all kinds of hearing loss. We have demonstrated that threshold differences between PTA and ASSR are negligible in the clinical routine. The "estimated" ASSR audiogram is a good approach for communicating ASSR results to the average user.

Comparison of ABR and ASSR using NB-chirp-stimuli in children with severe and profound hearing loss

INTRODUCTION

Objective techniques for hearing threshold estimation in infants and children with profound or severe hearing loss play a key role in pediatric audiology to prevent speech acquisition disorders by choosing the adequate therapy. Auditory brainstem responses and auditory steady-state responses are available for frequency-dependent hearing threshold estimations and both techniques show strong correlations. However, various systems and stimuli are available, which is one reason why comparison is challenging, and, so far, no single "gold standard" could be established for hearing threshold estimation in children suffering from profound or severe hearing loss. The aim of the study was to compare hearing threshold estimations in children with profound or severe hearing loss derived with narrow-band CE-chirps evoked auditory brainstem responses and auditory steady-state response.

SUBJECTS

and Methods: 71 children (121 ears) with an age from 3 month to 15 years were measured with the Interacoustics Eclipse EP25 ABR system® (Denmark) with narrow-band CE-chirps® at 500, 1000, 2000 and 4000 Hz under identical conditions.

RESULTS

Auditory brainstem responses and auditory steady-state responses highly correlate (r = 0.694, p < 0.001). Correlation coefficients differ depending on the center frequency and patient age. Generally, auditory steady-state responses show a better hearing threshold than auditory brainstem responses or a remaining hearing threshold when auditory brainstem responses could not be obtained. In approximately 15% of cases this would have affected the therapeutic strategy when only taking one technique into account.

CONCLUSION

Auditory brainstem responses and auditory steady-state responses should be jointly used in the diagnostic approach in children with suspected profound or severe hearing loss.

A Method for Tracking the Time Evolution of Steady-State Evoked Potentials

Neural entrainment refers to the synchronization of neural activity to the periodicity of sensory stimuli. This synchronization defines the generation of steady-state evoked responses (i.e., oscillations in the electroencephalogram phase-locked to the driving stimuli). The classic interpretation of the amplitude of the steady-state evoked responses assumes a stereotypical time-invariant neural response plus random background fluctuations, such that averaging over repeated presentations of the stimulus recovers the stereotypical response. This approach ignores the dynamics of the steady-state, as in the case of the adaptation elicited by prolonged exposures to the stimulus. To analyze the dynamics of steady-state responses, it can be assumed that the time evolution of the response amplitude is the same in different stimulation runs separated by sufficiently long breaks. Based on this assumption, a method to characterize the time evolution of steady-state responses is presented. A sufficiently large number of recordings are acquired in response to the same experimental condition. Experimental runs (recordings) are column-wise averaged (i.e., runs are averaged but epoch within recordings are not averaged with the preceding segments). The column-wise averaging allows analysis of steady-state responses in recordings with remarkably high signal-to-noise ratios. Therefore, the averaged signal provides an accurate representation of the time evolution of the steady-state response, which can be analyzed in both the time and frequency domains. In this study, a detailed description of the method is provided, using steady-state visually evoked potentials as an example of a response. Advantages and caveats are evaluated based on a comparison with single-trial methods designed to analyze neural entrainment.

Objective Estimation of Sensory Thresholds Based on Neurophysiological Parameters

Reliable determination of sensory thresholds is the holy grail of signal detection theory. However, there exists no assumption-independent gold standard for the estimation of thresholds based on neurophysiological parameters, although a reliable estimation method is crucial for both scientific investigations and clinical diagnosis. Whenever it is impossible to communicate with the subjects, as in studies with animals or neonates, thresholds have to be derived from neural recordings or by indirect behavioral tests. Whenever the threshold is estimated based on such measures, the standard approach until now is the subjective setting-either by eye or by statistical means-of the threshold to the value where at least a "clear" signal is detectable. These measures are highly subjective, strongly depend on the noise, and fluctuate due to the low signal-to-noise ratio near the threshold. Here we show a novel method to reliably estimate physiological thresholds based on neurophysiological parameters. Using surrogate data we demonstrate that fitting the responses to different stimulus intensities with a hard sigmoid function, in combination with subsampling, provides a robust threshold value as well as an accurate uncertainty estimate. This method has no systematic dependence on the noise and does not even require samples in the full dynamic range of the sensory system. We prove that this method is universally applicable to all types of sensory systems, ranging from somatosensory stimulus processing in the cortex to auditory processing in the brain stem.

Hearing threshold estimation by auditory steady state responses (ASSR) in children

Hearing threshold identification in very young children is always problematic and challenging. Electrophysiological testing such as auditory brainstem responses (ABR) is still considered the most reliable technique for defining the hearing threshold. However, over recent years there has been increasing evidence to support the role of auditory steady-state response (ASSR). Retrospective study. Forty-two children, age range 3-189 months, were evaluated for a total of 83 ears. All patients were affected by sensorineural hearing loss (thresholds ≥ 40 dB HL according to a click-ABR assessment). All patients underwent ABRs, ASSR and pure tone audiometry (PTA), with the latter performed according to the child’s mental and physical development. Subjects were divided into two groups: A and B. The latter performed all hearing investigations at the same time as they were older than subjects in group A, and it was then possible to achieve electrophysiological and PTA tests in close temporal sequence. There was no significant difference between the threshold levels identified at the frequencies tested (0.25, 0.5, 1, 2 and 4 kHz), by PTA, ABR and ASSR between the two groups (Mann Whitney U test, p < 0.05). Moreover, for group A, there was no significant difference between the ASSR and ABR thresholds when the children were very young and the PTA thresholds subsequently identified at a later stage. Our results show that ASSR can be considered an effective procedure and a reliable test, particularly when predicting hearing threshold in very young children at lower frequencies (including 0.5 kHz).

Evaluation of Speed and Accuracy of Next-Generation Auditory Steady State Response and Auditory Brainstem Response Audiometry in Children With Normal Hearing and Hearing Loss

OBJECTIVES

The first objective of this study was to compare the predicted audiometric thresholds obtained by auditory steady state response (ASSR) and auditory brainstem response (ABR) in infants and toddlers when both techniques use optimal stimuli and detection algorithms. This information will aid in determining the basis for large discrepancies in ABR and ASSR measures found in past studies. The hypothesis was that advancements in ASSR response detection would improve (lower) thresholds and decrease discrepancies between the thresholds produced by the two techniques. The second objective was to determine and compare test times required by the two techniques to predict thresholds for both ears at the 4 basic audiometric frequencies of 500, 1000, 2000, and 4000 Hz.

DESIGN

A multicenter clinical study was implemented at three university-based children's hospital audiology departments. Participants were 102 infants and toddlers referred to the centers for electrophysiologic testing for audiometric purposes. The test battery included wideband tympanometry, distortion-product otoacoustic emissions, and threshold measurements at four frequencies in both ears using ABR and ASSR (randomized) as implemented on the Interacoustics Eclipse systems with "Next-Generation" ASSR detection and FMP analysis for ABR. Both methods utilized narrow band CE-Chirp stimuli. Testers were trained on a specialized test battery designed to minimize test time for both techniques. Testing with both techniques was performed in one session. Thresholds were evaluated and confirmed by the first author and correction factors were applied. Test times were documented in system software.

RESULTS

Corrected thresholds for ABR and ASSR were compared by regression, by the Bland-Altman technique and by matched pairs t tests. Thresholds were significantly lower for ASSR than ABR. The ABR-ASSR discrepancy at 500 Hz was 14.39 dB, at 1000 Hz was 10.12 dB, at 2000 Hz was 3.73 dB, and at 4000 Hz was 3.67 dB. The average test time for ASSR of 19.93 min (for 8 thresholds) was found to be significantly lower (p < 0.001) than the ABR test time of 32.15 min. One half of the subjects were found to have normal hearing. ASSR thresholds plotted in dB nHL for normal-hearing children in this study were found to be the lowest yet described except for one study which used the same technology.

CONCLUSIONS

This study found a reversal of previous findings with up to 14 dB lower thresholds found when using the ASSR technique with "Next-Generation" detection as compared with ABR using an automated detection (FMP). The test time for an audiogram prediction was significantly lower when using ASSR than ABR but was excellent by clinical standards for both techniques. ASSRs improved threshold performance was attributed to advancements in response detection including utilization of information at multiple harmonics of the modulation frequency. The stimulation paradigm which utilized narrow band CE-Chirps also contributed to the low absolute levels of the thresholds in nHL found with both techniques.

Estimation of auditory steady-state responses based on the averaging of independent EEG epochs

The amplitude of auditory steady-state responses (ASSRs) generated in the brainstem of rats exponentially decreases over the sequential averaging of EEG epochs. This behavior is partially due to the adaptation of the ASSR induced by the continuous and monotonous stimulation. In this study, we analyzed the potential clinical relevance of the ASSR adaptation. ASSR were elicited in eight anesthetized adult rats by 8-kHz tones, modulated in amplitude at 115 Hz. We called independent epochs to those EEG epochs acquired with sufficiently long inter-stimulus interval, so the ASSR contained in any given epoch is not affected by the previous stimulation. We tested whether the detection of ASSRs is improved when the response is computed by averaging independent EEG epochs, containing only unadapted auditory responses. The improvements in the ASSR detection obtained with standard, weighted and sorted averaging were compared. In the absence of artifacts, when the ASSR was elicited by continuous acoustic stimulation, the computation of the ASSR amplitude relied upon the averaging method. While the adaptive behavior of the ASSR was still evident after the weighting of epochs, the sorted averaging resulted in under-estimations of the ASSR amplitude. In the absence of artifacts, the ASSR amplitudes computed by averaging independent epochs did not depend on the averaging procedure. Averaging independent epochs resulted in higher ASSR amplitudes and halved the number of EEG epochs needed to be acquired to achieve the maximum detection rate of the ASSR. Acquisition protocols based on averaging independent EEG epochs, in combination with appropriate averaging methods for artifact reduction might contribute to develop more accurate hearing assessments based on ASSRs.

Acoustic Reflex Testing in Neonatal Hearing Screening and Subsequent Audiological Evaluation

PURPOSE

The aims of the study were to examine the acoustic reflex screening and threshold in healthy neonates and those at risk of hearing loss and to determine the effect of birth weight and gestational age on acoustic stapedial reflex (ASR).

METHOD

We assessed 18 healthy neonates (Group I) and 16 with at least 1 risk factor for hearing loss (Group II); all of them passed the transient evoked otoacoustic emission test that assessed neonatal hearing. The test battery included an acoustic reflex screening with activators of 0.5, 1, 2, and 4 kHz and broadband noise and an acoustic reflex threshold test with all of them, except for the broadband noise activator.

RESULTS

In the evaluated neonates, the main risk factors were the gestational age at birth and a low birth weight; hence, these were further analyzed. The lower the gestational age at birth and birth weight, the less likely that an acoustic reflex would be elicited by pure-tone activators. This effect was significant at the frequencies of 0.5, 1, and 2 kHz for gestational age at birth and at the frequencies of 1 and 2 kHz for birth weight. When the broadband noise stimulus was used, a response was elicited in all neonates in both groups. When the pure-tone stimulus was used, the Group II showed the highest acoustic reflex thresholds and the highest percentage of cases with an absent ASR. The ASR threshold varied from 50 to 100 dB HL in both groups. Group II presented higher mean ASR thresholds than Group I, this difference being significant at frequencies of 1, 2, and 4 kHz.

CONCLUSIONS

Birth weight and gestational age at birth were related to the elicitation of the acoustic reflex. Neonates with these risk factors for hearing impairment were less likely to exhibit the acoustic reflex and had higher thresholds.

French Society of ENT (SFORL) guidelines (short version): Audiometry in adults and children

INTRODUCTION

French Society of ENT (SFORL) good practice guidelines for audiometric examination in adults and children.

METHODS

A multidisciplinary working group performed a review of the scientific literature. Guidelines were drawn up, reviewed by an independent reading group, and finalized in a consensus meeting.

RESULTS

Audiometry should be performed in an acoustically controlled environment (<30dBA); audiometer calibration should be regularly checked; and patient-specific masking rules should be systematically applied. It should be ensured that masking is not overmasking. Adult pure-tone audiometry data should be interpreted taking account of clinical data, speech audiometry and impedancemetry. In case of discrepancies between clinical and pure-tone and speech audiometry data, objective auditory tests should be perform. In children aged 2 years or younger, subjective audiometry should be associated to behavioral audiometry adapted to the child's age. In suspected hearing impairment, behavioral audiometry should be systematically supplemented by objective hearing tests to determine and confirm the level and type of hearing impairment.

Assessment of auditory threshold using Multiple Magnitude-Squared Coherence and amplitude modulated tones monaural stimulation around 40 Hz

BACKGROUND AND OBJECTIVE

The use of objective detection techniques applied to the auditory steady-state responses (ASSRs) for the assessment of auditory thresholds has been investigated over the years. The idea consists in setting up the audiometric profile without subjective inference from patients and evaluators. The challenge encountered is to reduce the detection time of auditory thresholds reaching high correlation coefficients between the objective and the conventional thresholds, as well as reducing difference between thresholds.

METHODS

This paper evaluated the use of the Multiple Magnitude-Squared Coherence (MMSC) in Auditory Steady-State Responses (ASSRs) evoked by amplitude modulated tones around 40 Hz, attaining objective audiograms, which were, later, compared to conventional audiograms. It was proposed an analysis of the electroencephalogram signals of ten subjects, monaurally stimulated, in the intensities 15, 20, 25, 30, 40 and 50 dB SPL, for carrier frequencies of 0.5, 1, 2 and 4 kHz. After the detection protocol parameters variation, two detectors were selected according to behavioral thresholds.

RESULTS

The method of this study resulted in a Maximum detector with correlation coefficient r = 0.9262, mean difference between the objective and behavioral thresholds of 6.44 dB SPL, average detection time per ear of 49.96 min and per stimulus of 2.08 min. Meanwhile, the Fast detector presented coefficient r = 0.8401, mean difference of 6.81 dB SPL, average detection time of 28.20 min per ear and 1.18 per stimulus.

CONCLUSIONS

The results of this study indicate that the MMSC use in the auditory responses detection might provide a reliable and efficient estimation of auditory thresholds.

Binaural Interaction Effects of 30-50 Hz Auditory Steady State Responses

OBJECTIVES

Auditory stimuli modulated by modulation frequencies within the 30 to 50 Hz region evoke auditory steady state responses (ASSRs) with high signal to noise ratios in adults, and can be used to determine the frequency-specific hearing thresholds of adults who are unable to give behavioral feedback reliably. To measure ASSRs as efficiently as possible a multiple stimulus paradigm can be used, stimulating both ears simultaneously. The response strength of 30 to 50Hz ASSRs is, however, affected when both ears are stimulated simultaneously. The aim of the present study is to gain insight in the measurement efficiency of 30 to 50 Hz ASSRs evoked with a 2-ear stimulation paradigm, by systematically investigating the binaural interaction effects of 30 to 50 Hz ASSRs in normal-hearing adults.

DESIGN

ASSRs were obtained with a 64-channel EEG system in 23 normal-hearing adults. All participants participated in one diotic, multiple dichotic, and multiple monaural conditions. Stimuli consisted of a modulated one-octave noise band, centered at 1 kHz, and presented at 70 dB SPL. The diotic condition contained 40 Hz modulated stimuli presented to both ears. In the dichotic conditions, the modulation frequency of the left ear stimulus was kept constant at 40 Hz, while the stimulus at the right ear was either the unmodulated or modulated carrier. In case of the modulated carrier, the modulation frequency varied between 30 and 50 Hz in steps of 2 Hz across conditions. The monaural conditions consisted of all stimuli included in the diotic and dichotic conditions.

RESULTS

Modulation frequencies ≥36 Hz resulted in prominent ASSRs in all participants for the monaural conditions. A significant enhancement effect was observed (average: ~3 dB) in the diotic condition, whereas a significant reduction effect was observed in the dichotic conditions. There was no distinct effect of the temporal characteristics of the stimuli on the amount of reduction. The attenuation was in 33% of the cases >3 dB for ASSRs evoked with modulation frequencies ≥40 Hz and 50% for ASSRs evoked with modulation frequencies ≤36 Hz.

CONCLUSIONS

Binaural interaction effects as observed in the diotic condition are similar to the binaural interaction effects of middle latency responses as reported in the literature, suggesting that these responses share a same underlying mechanism. Our data also indicated that 30 to 50 Hz ASSRs are attenuated when presented dichotically and that this attenuation is independent of the stimulus characteristics as used in the present study. These findings are important as they give insight in how binaural interaction affects the measurement efficiency. The 2-ear stimulation paradigm of the present study was, for the most optimal modulation frequencies (i.e., ≥40 Hz), more efficient than a 1-ear sequential stimulation paradigm in 66% of the cases.

Assessment of frequency specific auditory steady-state response using amplitude modulation with 2-order exponential envelope

This study investigated the performance of Frequency Specific Auditory Steady-State Response (FS-ASSR) detection elicited by the amplitude modulated tone with 2-order exponential envelope (AM2), using objective response detection (ORD) techniques of Spectral F-Test (SFT) and Magnitude Squared Coherence (MSC). ASSRs from 24 normal hearing adults were obtained during binaural multi-tone stimulation of amplitude-modulation (AM) and AM2 at intensities of 60, 45 and 30 dBSPL. The carrier frequencies were 500, 1000, 2000, and 4000 Hz, modulated between 77 and 105 Hz. AM2 achieve FS-ASSR amplitudes higher than AM by 16%, 18% and 12% at 60, 45 and 30 dBSPL, respectively, with a major increase at 500 Hz (22.5%). AMS2PL increased the Detection Rate (DR) up to 8.3% at 500 Hz for 30 dBSPL, which is particularly beneficial for FS-ASSR detection near the hearing threshold. In addition, responses in 1000 and 4000 Hz were consistently increased. The MSC and SFT presented no differences in Detection Rate (DR). False Detection Rate (FDR) was close to 5% for both techniques and tones. Detection times to reach DR over 90% were 3.5 and 4.9 min at 60 and 45 dBSPL, respectively. Further investigation concerning efficient multiple FS-ASSR is still necessary, such as testing subjects with hearing loss.

Towards Objective Measures of Functional Hearing Abilities

AIMS

People with impaired hearing often have difficulties in hearing sounds in a noisy background. This problem is partially a result of the auditory systems reduced capacity to process temporal information in the sound signal. In this study we examined the relationships between perceptual sensitivity to temporal fine structure (TFS) cues, brainstem encoding of complex harmonic and amplitude modulated sounds, and the ability to understand speech in noise. Understanding these links will allow the development of an objective measure that could be used to detect changes in functional hearing before the onset of permanent threshold shifts.

METHODS

We measured TFS sensitivity and speech in noise performance (QuickSIN) behaviourally in 34 normally hearing adults with ages ranging from 18 to 63 years. We recorded brainstem responses to complex harmonic sounds and a 4000 Hz carrier signal modulated at 110 Hz. We performed cross correlations between the stimulus waveforms and scalp-recorded brainstem responses to generate a simple measure of stimulus encoding accuracy, and correlated these measures with age, TFS sensitivity and speech-in-noise performance.

RESULTS

Speech-in-noise performance was positively correlated with TFS sensitivity, and negatively correlated with age. TFS sensitivity was also positively correlated with stimulus encoding accuracy for the complex harmonic stimulus, while increasing age was associated with lower stimulus encoding accuracy for the modulated tone stimulus.

CONCLUSIONS

The results show that even in a group of people with normal hearing, increasing age was associated with reduced speech understanding, reduced TFS sensitivity, and reduced stimulus encoding accuracy (for the modulated tone stimulus). People with good TFS sensitivity also generally had less faithful brainstem encoding of a complex harmonic tone.

Gender and modulation frequency effects on auditory steady state response (ASSR) thresholds

For estimating behavioral hearing thresholds, auditory steady state response (ASSR) can be reliably evoked by stimuli at low and high modulation frequencies (MFs). In this regard, little is known regarding ASSR thresholds evoked by stimuli at different MFs in female and male participants. In fact, recent data suggest that 40-Hz ASSR is influenced by estrogen level in females. Hence, the aim of the present study was to determine the effect of gender and MF on ASSR thresholds in young adults. Twenty-eight normally hearing participants (14 males and 14 females) were enrolled in this study. For each subject, ASSR thresholds were recorded with narrow-band chirps at 500, 1,000, 2,000, and 4,000 Hz carrier frequencies (CFs) and at 40 and 90 Hz MFs. Two-way mixed ANOVA (with gender and MF as the factors) revealed no significant interaction effect between factors at all CFs (p > 0.05). The gender effect was only significant at 500 Hz CF (p < 0.05). At 500 and 1,000 Hz CFs, mean ASSR thresholds were significantly lower at 40 Hz MF than at 90 Hz MF (p < 0.05). Interestingly, at 2,000 and 4,000 Hz CFs, mean ASSR thresholds were significantly lower at 90 Hz MF than at 40 Hz MF (p < 0.05). The lower ASSR thresholds in females might be due to hormonal influence. When recording ASSR thresholds at low MF, we suggest the use of gender-specific normative data so that more valid comparisons can be made, particularly at 500 Hz CF.

Auditory-steady-state response reliability in the audiological diagnosis after neonatal hearing screening

INTRODUCTION AND OBJECTIVES

Conventional audiometry is the gold standard for quantifying and describing hearing loss. Alternative methods become necessary to assess subjects who are too young to respond reliably. Auditory evoked potentials constitute the most widely used method for determining hearing thresholds objectively; however, this stimulus is not frequency specific. The advent of the auditory steady-state response (ASSR) leads to more specific threshold determination. The current study describes and compares ASSR, auditory brainstem response (ABR) and conventional behavioural tone audiometry thresholds in a group of infants with various degrees of hearing loss.

METHODS

A comparison was made between ASSR, ABR and behavioural hearing thresholds in 35 infants detected in the neonatal hearing screening program.

RESULTS

Mean difference scores (±SD) between ABR and high frequency ABR thresholds were 11.2 dB (±13) and 10.2 dB (±11). Pearson correlations between the ASSR and audiometry thresholds were 0.80 and 0.91 (500Hz); 0.84 and 0.82 (1000Hz); 0.85 and 0.84 (2000Hz); and 0.83 and 0.82 (4000Hz).

CONCLUSION

The ASSR technique is a valuable extension of the clinical test battery for hearing-impaired children.

Hearing aid validation based on 40 Hz auditory steady-state response thresholds

BACKGROUND AND AIM

Aided thresholds can be used for prediction of success of hearing aids and to choose between hearing aids and cochlear implants. This study aimed to compare characteristics of aided and unaided auditory steady-state responses (ASSRs).

METHODS

A total of 30 moderate to profoundly hearing-impaired subjects participated in this study. The subjects underwent acoustic immittance, behavioral audiometry, and ASSR with the modulation rate of 40 Hz, first without a hearing aid and then with a hearing aid. Sixteen people with normal hearing and 17 people with severe hearing loss were included in biological calibration of the sound field.

RESULTS

There was a significant difference between unaided behavioral and ASSR thresholds in all test frequencies (mean difference of unaided behavioral ASSR thresholds: 6.19 dB; P = 0.02 at 500 Hz, P < 0.001 at 1000 and 2000 Hz, and P = 0.02 for 4000 Hz). There was also a significant difference between aided behavioral and ASSR thresholds at 1000 and 2000 Hz (P < 0.001) but not at 500 (P = 0.14) and 4000 (P = 0.23) Hz (mean difference of behavioral ASSR thresholds was 4.33 dB). Despite observing any unaided responses, aided thresholds could be recorded in some severe to profoundly hearing-impaired subjects. The number of recordable thresholds was directly related to speech clarity and speech-reading ability. Multi-frequency stimulation elevated the ASSR threshold, especially for the higher frequencies and in the aided condition.

CONCLUSION

Functional and ASSR gains show less difference than threshold data. Therefore, comparing gains instead of thresholds is more accurate for validation of hearing aids. The probability of success of hearing aids appears to be poor if ASSRs (especially aided ones) cannot be recorded. If special care is taken in the fitting of hearing aids and the testing conditions, aided ASSR testing could be a useful tool for validation of hearing aids and the cochlear implant decision-making process.

The effect of the transducers on paediatric thresholds estimated with auditory steady-state responses

The objective of this study was to investigate the usefulness of auditory steady-state responses (ASSRs) for estimating hearing thresholds in young children, compared with behavioural thresholds. The second objective was to investigate ASSR thresholds obtained with insert earphones versus supra-aural headphones to determine which transducer produces ASSR thresholds most similar to behavioural thresholds measured with supra-aural headphones. This retrospective study included 29 participants (58 ears): 12 children (24 ears) in the insert group and 17 children (34 ears) in the supra-aural group. No general anaesthesia was used. For both groups, there was a strong correlation between behavioural and ASSR thresholds, with a stronger correlation for the insert group. When behavioural thresholds are difficult to obtain, ASSR may be a useful objective measure that can be combined with other audiometric procedures to estimate hearing thresholds and to determine appropriate auditory rehabilitation approaches.

Habituation of Auditory Steady State Responses Evoked by Amplitude-Modulated Acoustic Signals in Rats

Generation of the auditory steady state responses (ASSR) is commonly explained by the linear combination of random background noise activity and the stationary response. Based on this model, the decrease of amplitude that occurs over the sequential averaging of epochs of the raw data has been exclusively linked to the cancelation of noise. Nevertheless, this behavior might also reflect the non-stationary response of the ASSR generators. We tested this hypothesis by characterizing the ASSR time course in rats with different auditory maturational stages. ASSR were evoked by 8-kHz tones of different supra-threshold intensities, modulated in amplitude at 115 Hz. Results show that the ASSR amplitude habituated to the sustained stimulation and that dishabituation occurred when deviant stimuli were presented. ASSR habituation increased as animals became adults, suggesting that the ability to filter acoustic stimuli with no-relevant temporal information increased with age. Results are discussed in terms of the current model of the ASSR generation and analysis procedures. They might have implications for audiometric tests designed to assess hearing in subjects who cannot provide reliable results in the psychophysical trials.

Auditory steady-state response thresholds in adults with conductive and mild to moderate sensorineural hearing loss

Background:

The Auditory steady state response (ASSR) provides a frequency-specific and automatic assessment of hearing sensitivity and is used in infants and difficult-to-test adults.

Objectives:

The aim of this study was to compare the ASSR thresholds among various types (normal, conductive, and sensorineural), degree (normal, mild, and moderate), and configuration (flat and sloping) of hearing sensitivity, and measuring the cutoff point between normal condition and hearing loss for different frequencies.

Patients and Methods:

This clinical trial was performed in Iran and included patients who were referred from Ear, Nose, and Throat Department. A total of 54 adults (27 with sensorineural hearing loss, 17 with conductive hearing losses, and 10 with normal hearing) were randomly chosen to participate in our study. The type and degree of hearing loss were determined through testing by otoscopy, tympanometry, acoustic reflex, and pure tone audiometry. Then the ASSR was tested at carrier frequencies of 500, 1000, 2000, and 4000 Hz.

Results:

The ASSR accurately estimates the behavioral thresholds as well as flat and sloping configurations. There was no correlation between types of hearing loss and difference of behavioral and ASSR thresholds (P = 0.69). The difference between ASSR and behavioral thresholds decreased as severity of hearing loss increased. The 40, 35, 30, and 35 dB could be considered as cutoffs between normal hearing and hearing loss for 500, 1000, 2000, and 4000 Hz, respectively.

Conclusions:

The ASSR can accurately predict the degree and configuration of hearing loss and discriminate the normal hearing from mild or moderate hearing loss and mild from moderate hearing loss, except for 500 Hz. The Air-conducted ASSR could not define the type of hearing loss.

Refining the audiological assessment in children using narrow-band CE-Chirp-evoked auditory steady state responses

OBJECTIVE

To demonstrate the feasibility and reliability of simultaneous binaural recording of auditory steady-state responses (ASSR) in young children using narrow-band CE-Chirps as stimuli.

DESIGN

Prospective cohort study comparing ASSR thresholds to four frequency stimuli (0.5, 1, 2, and 4 kHz), with click-evoked auditory brainstem responses (ABR) and behavioral response audiometry.

STUDY SAMPLE

Thirty-two young children (mean age 7.4 ± 5.2 months) referred for auditory assessment were evaluated.

RESULTS

The mean duration for ABR recordings was 13.3 ± 7.2 min versus 22.9 ± 15.8 min for ASSR (p < 0.01). ASSR (means of 2 and 4 kHz thresholds) were highly correlated with ABR thresholds (R2 = 0.935, p < 0.001), though significantly different (3 ± 10.7 dB, p = 0.02). ASSR (means of 0.5, 1, 2, and 4 kHz thresholds) were highly correlated with mean behavioral response audiometry thresholds (R2 = 0.968, p < 0.001). ASSRs were highly and significantly correlated with behavioral response audiometry at 0.5, 1, 2, and 4 kHz (R2 = 0.845, 0.907, 0.929, and 0.859 respectively, p < 0.001). 87.5% and 90.7% ASSR thresholds were within a ± 10 dB range around their corresponding ABR and mean behavioral response audiometry thresholds.

CONCLUSIONS

Narrow-band CE-Chirps allow a fast and reliable assessment of auditory thresholds in children, especially in the low-frequency range, by comparison with other stimuli.

The role of current audiological tests in the early diagnosis of hearing impairment in infant

This study aims to compare the various audiological tests that are currently available as screening tools for infant hearing assessment. In developing countries, which have limited resources, it is imperative to design a screening programme that is easy to perform, gives accurate results, has good patient acceptability and is cost effective. Fifty infants, 3-12 months of age, were subjected to BOT for hearing, transient-evoked oto-acoustic emissions (TEOAEs), automated auditory brainstem response (AABR) test, auditory brainstem evoked response (ABR) testing and auditory steady state response (ASSR). The sensitivity and specificity of the various tests was calculated, with ABR test as the gold standard. We also compared them for average time taken, cost factors, ease of performance, number of repeat tests required and patient acceptability. All the screening tests, TEOAE, AABR and behavioral observation test had reasonably high sensitivity. Specificity was highest for behavioral observation testing (67.7 %) and AABR (64.5 %), but low for OAE test (48.3 %). The cost and time taken for each test was least for the behavioral observation test, which also did not require any repeat testing. TEOAE and AABR incur a recurring cost of approximately one dollar per test. However, in 12 and 28 % of the babies had to be called back for repeat testing, respectively. ASSR, as a diagnostic test, has a 100 % sensitivity and high specificity but scores down on the cost involved, time taken and the number of repeat tests required. Overall parent acceptability was the highest for behavioral observation test, as it was non-invasive and easy to perform. Behavioral observation combined with TEOAE/AABR, can be fairly accurate as screening tests for hearing loss in infants. Considering its ease of performance and low cost, behavioral observation could be used as a screening test for detection of hearing loss in infants, in those countries/places where universal neonatal hearing screening is not yet available.

Prognostic validity of dichotic multiple frequencies auditory steady-state responses versus distortion product otoacoustic emissions in hearing screening of high risk neonates

OBJECTIVE

To determine the validity of dichotic multiple frequencies auditory steady-state responses (ASSR) as a hearing screening technique versus using distortion product otoacoustic emissions (DPOAEs) among high-risk neonates.

METHODS

A cross sectional study was performed on 118 high-risk neonates by means of dichotic multiple frequencies ASSR and DPOAE for hearing screening. DPOAE results were used as the standard for hearing screening in parallel with ASSR. Dichotic multiple frequencies ASSR results were analyzed by means of F-value of less or greater than 0.05 criteria as a pass-fail for the responses. Dichotic multiple ASSR hearing screening technique was considered in two intensity levels at 40 and 70 dB HL. The ASSRs thresholds were measured in high risk neonates with and without hearing deficits as determined by DPOAES. The results of ASSR and DPOAE were compared to be gathered by contingency table in order to obtain sensitivity, specificity and other different statistical values. Average performing times for the tests were analyzed.

RESULTS

The specificity of dichotic multiple ASSR was 92.6%, 93.8% and the sensitivity was 71.6%, 62.2% at the 70 and 40 dB hearing levels, respectively. Mean ASSR thresholds for normal-hearing infants at an average corrected age of 6 days were 32.2 ± 12.2, 29.8 ± 10.2, 26.2 ± 11.4 and 30.4 ± 10.8 dB HL for 0.5, 1, 2 and 4 kHz, respectively. The average times for performing the tests were 18.7 and 32.9 min respectively.

CONCLUSIONS

ASSR with this special paradigm is a fairly desirable method for hearing screening of high-risk neonates. There is good concordance between ASSRs and DOPAEs results among high risk neonates referred for hearing screening. The sensitivity and specificity of this test is sufficient for hearing screening in high risk neonates. This test could be valuable for rapid confirmation of normal thresholds. As long as further research have not been conducted on ASSR, great caution should be made to interpret the results of ASSR as a hearing screening technique in young infants and also additional techniques such as the tone-evoked ABRs should be used to cross-check results. It's still too soon to recommend ASSRs as a standalone electrophysiologic measure of hearing thresholds in infants.

Auditory steady-state response in children with cochlear hearing loss

BACKGROUND

auditory steady-state response (ASSR) is indicated as a promising technique in the assessment of the hearing status of children.

AIM

to investigate the level of agreement between the results of the ASSR and the visual reinforcement audiometry (VRA) in a group of children, thus examining the clinical applicability of this technique in hearing assessment of children.

METHOD

participants were 14 children with ages between 4 and 36 months (mean 16 months) with the diagnosis of cochlear hearing loss. The ASSR was recorded in the frequencies of 0.5, 1, 2 and 4kHz for multiple simultaneous stimulation and the results were compared with the visual reinforcement audiometry (VRA).

RESULTS

the intraclass correlation coefficients between ASSR and VRA were 0.90, 0.93, 0.93 and 0.89 respectively for the frequencies of 0.5, 1, 2 and 4kHz, indicating a strong correlation between the techniques.

CONCLUSION

the ASSR can provide accurate information to support the selection of hearing aids for children when it is not possible to perform the VRA.

Potencial Evocado Auditivo de Estado Estável com estímulo de ruído branco modulado em amplitude em triagem auditiva neonatal

OBJETIVO: verificar a utilização do estímulo ruído branco, modulado em amplitude, no exame de Potencial Evocado Auditivo de Estado Estável (PEAEE). MÉTODO: foram avaliados 30 neonatos e lactentes, na Maternidade do Hospital das Clínicas da UFPE, que realizaram os exames de Emissões Otoacústicas Transientes (EOAT) e PEAEE, com ruído branco de amplitude modulada. RESULTADOS: para o exame de PEAEE, sugere-se que a intensidade ideal para o ponto de corte seja 50 dB NPS, para os casos com passa na triagem auditiva, com o exame de EOAT. CONCLUSÃO: o exame de PEAEE, realizado com ruído branco, modulado em amplitude, parece ser promissor como ferramenta de triagem auditiva. Entretanto, estudos são necessários para observar a relação entre os limiares das respostas auditivas de estado estável utilizando-se tons puros e ruído branco, a fim de melhor elucidar e definir parâmetros e protocolos de sua utilização.

Real-time detection of auditory steady-state responses

Detection of the auditory steady-state responses (ASSRs) is a difficult task, its main technical impediment is no other than the excessively lengthy recording time required for the estimation process due to the extremely low signal-to-noise ratio (SNR). To improve the detection rate of ASSRs, a new observer-based real-time ASSR detector is derived as an alternate solution to the existing methods. The ASSR detector has a simple structure, and provides fast and reliable signal detection. Simulation and experimental recorded data were used to evaluate the performances of the proposed approach. Compared with the conventional methods, the proposed method requires shorter recording time which could be proven as a valuable hearing screening or diagnostic tool.

[Newborn hearing screening test with multiple auditory steady-state responses]

INTRODUCTION

The techniques most frequently used within a screening context (otoacoustic emissions and click auditory brainstem response) have well-known limitations in hearing loss detection.

OBJECTIVE

This study examines the feasibility of a semi-automated multiple auditory steady-state responses (MSSR) system designed for neonatal hearing screening.

METHODS

A sample of 50 newborns without risk factors (well-babies) was tested within two weeks of birth. All had detectable auditory brainstem responses to clicks down to 40dB nHL in both ears. Two amplitude modulated carrier tones of 500 and 2,000Hz were mixed together and presented simultaneously. Each infant (and ear) was screened with the MSSR system; to simulate a hearing loss, a recording without stimulation was also obtained.

RESULTS

Mean auditory thresholds were 42.5±7dB HL at 500Hz and 35.5±6dB HL at 2,000Hz. The average duration of the MSSR recording was 2.6±1.6 minutes for each tested ear and the overall duration of the screening procedure (including electrode fitting and infant preparation) was 17.8±3.7 minutes. The diagnostic sensibility and the positive predictive values of the MSSR semi-automatic screening system was 100% and 96% respectively, with specificity of 96% and negative predictive values of 100%.

CONCLUSIONS

Although the diagnostic efficiency of the semi-automated MSSR system was found adequate, further technological improvements are still necessary to facilitate its use in the context of universal newborn hearing screening program.

Sensitivity and specificity of auditory steady-state response testing

INTRODUCTION

The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones.

OBJECTIVE

The aim of this study was to determine the sensitivity and specificity of auditory steady-state response testing in detecting lesions and dysfunctions of the central auditory nervous system.

METHODS

Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady-state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady-state response-estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated.

RESULTS

Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady-state response-estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group.

DISCUSSION

Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR-estimated thresholds and actual behavioral thresholds; ASSR-estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR-estimated thresholds and the behavioral thresholds is impaired temporal resolution.

CONCLUSIONS

The overall sensitivity of auditory steady-state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.

[Auditory steady-state responses--the state of art]

The auditory steady-state responses (ASSR) is quite a new method of electrophysiological threshold estimation with no clinical standards. It was the aim of this study to review practical and theoretical thesis of ASSR and mention recent recommendations and achievements of this technique. The most common application of ASSR is diagnosis of hearing loss in children together with ABR test. In this paper we mentioned information about influence of physiological factors (age, sex, state of arousal, handedness) and type of recording technique (electrodes placement, air and bone stimulation, occlusion effect, amplitude and frequency stimulation, multiple or single frequency stimulation, dichotic and monotic recording technique and type of hearing loss) on ASSR. We conclude that putting ASSR in clinical use as an standardized method it is necessary to do research with numerous groups of patients using the same equipment and parameters of tests.

Cochlear implantation in the very young child: issues unique to the under-1 population

Since the advent of cochlear implantation, candidacy criteria have slowly broadened to include increasingly younger patients. Spurred by evidence demonstrating both perioperative safety and significantly increased speech and language benefit with early auditory intervention, children younger than 12 months of age are now being successfully implanted at many centers. This review highlights the unique challenges involved in cochlear implantation in the very young child, specifically diagnosis and certainty of testing, anesthetic risk, surgical technique, intraoperative testing and postoperative programming, long-term safety, development of receptive and expressive language, and outcomes of speech perception. Overall, the current body of literature indicates that cochlear implantation prior to 1 year of age is both safe and efficacious.

Threshold prediction in children with sensorioneural hearing loss using the auditory steady-state responses and tone-evoked auditory brain stem response

OBJECTIVE

The purpose of this study was to compare ASSRs to tone-evoked ABR and to behavioral thresholds obtained on follow-up audiometry at 500, 1000, 2000, and 4000 Hz in infants and young children.

METHODS

The study included 17 infants and young children ages between 2 months and 3 years old, with sensorineural hearing loss. The ASSRs thresholds were compared with the tone-evoked ABR thresholds, and with the behavioral thresholds obtained on follow-up audiometry.

RESULTS

The correlation of tone-evoked ABR and ASSRs thresholds at 500, 1000, 2000 and 4000 Hz was 0.91, 0.76, 0.81, 0.89, respectively. ASSRs and behavioral hearing thresholds obtained on follow-up were highly correlated, with Pearson r values exceeding 0.94 at each of the test frequencies.

CONCLUSIONS

Multiple ASSRs have strong correlations to tone-evoked ABR and to behavioral thresholds obtained during follow-up in hearing impaired infants and young children. These results might be useful in order to provide further evidence for the use of multiple ASSRs, as an alternative tool to tone-evoked ABR, although further data are still required.

Presença de microfonismo coclear no peate-clique: diagnóstico diferencial entre espectro da neuropatia auditiva e perdas auditivas cocleares descendentes em crianças

TEMA: diagnóstico diferencial entre espectro da neuropatia auditiva e perdas auditivas cocleares descendentes em crianças com presença de microfonismo coclear no PEATE-clique. PROCEDIMENTOS: este relato de caso descreve os resultados da avaliação audiológica de duas crianças atendidas no Centro "Audição na Criança" da Divisão de Educação e Reabilitação dos Distúrbios da Comunicação da Pontifícia Universidade Católica de São Paulo (CeAC/DERDIC/PUCSP) que apresentaram microfonismo coclear no registro do PEATE-clique. As crianças foram submetidas às avaliações utilizando-se o PEATE-clique, o registro das emissões otoacústicas e a avaliação audiológica tonal, com a técnica da Audiometria de Reforço Visual. RESULTADOS: as avaliações comportamental, eletroacústica e eletrofisiológica revelaram que as crianças apresentam perda auditiva sensorioneural (coclear) com configuração descendente, de modo que a presença do microfonismo coclear no registro do PEATE-clique era provavelmente gerada pela preservação da cóclea nas frequências baixas. CONCLUSÃO: os casos apresentados mostram que na ausência das emissões otoacústicas e presença do microfonismo coclear, não se deve interpretar isoladamente cada exame, para que não ocorram equívocos no diagnóstico, que pode ser confundido com o Espectro da Neuropatia Auditiva. O microfonismo coclear pode aparecer em outras condições, tais como em perdas auditivas cocleares descendentes.

Comparison of MASTER and AUDERA for measurement of auditory steady-state responses Comparación de MASTER y AUDERA para la medición de las respuestas auditivas de estado estable

Two approaches to assess auditory steady-state responses (ASSR) are compared under similar test conditions: a monaural single-frequency technique with a detection method based on phase coherence (AUDERA), and a binaural multiple-frequency technique using the F-test (MASTER). ASSR thresholds at four frequencies were assessed with both methods in both ears of ten normal-hearing and ten hearing-impaired adult subjects, within a test duration of one hour. The test-retest reliability and the influence of prolonging the test duration are assessed. For the total subject group the multiple-frequency technique outperforms the single-frequency technique. In hearing-impaired subjects, however, both techniques perform equally well. Hearing thresholds can be estimated with a standard error of the estimate between 7 and 12 dB dependent on frequency. About 55% of the estimates are within 5 dB of the behavioral hearing threshold, and 94% within 15 dB. Prolonging the test duration improves the performance of both techniques.

Test accuracy and prognostic validity of multiple auditory steady state responses for targeted hearing screening

The test accuracy and prognostic validity of Multiple Auditory Steady State Responses (MSSR) and click Auditory Brainstem Responses (cABR) was compared within the context of a targeted screening protocol. A sample of 508 high-risk babies was first screened using cABR and MSSR (500 and 2000 Hz). All children (failed/ pass) were called back at three to four years of age to determine their hearing status (pure-tone audiometry). Although both methods showed an equally good test performance in the first screen (sensitivity: 100% and specificity: 92-95%), the MSSR may have some potential advantage to identify low-frequency hearing loss. Furthermore, the confirmatory audiometry with MSSR predicted the child hearing status more accurately than the cABR. In conclusion, the MSSR can provide valuable information for the diagnosis and management of infants earlier detected by a screening protocol and further developed might be also useful as a screening test.

Aided auditory steady-state responses in infants

Infants with hearing loss routinely receive hearing aids several months before reliable behavioral responses to amplified sound can be observed. This necessitates objective measures to validate hearing-aid fittings. A single report has demonstrated the use of ASSRs to determine aided thresholds in children but data in young infants is still lacking. The current study explored aided ASSR compared to unaided ASSR thresholds and subsequent behavioral thresholds in a group of six young infants with hearing loss who received hearing aids between three and six months of age. Aided ASSR thresholds were obtained in 83% of frequencies where aided behavioral thresholds were obtained, with a mean threshold difference of 13+/-13 dB. The aided ASSR-based threshold estimates were within 15 dB of behavioral thresholds in 63% of cases, indicating a moderate correlation (r = 0.55). Comparing aided and unaided ASSR measurements revealed an average functional gain of 36+/-15 dB. These results indicate that ASSRs can provide the first evidence of robust hearing aid benefit in young infants several months before behavioral responses are observed.

Newborn hearing screening and strategy for early detection of hearing loss in infants

OBJECTIVE

More than 80% of permanent hearing losses (HL) in children are congenital. Newborn hearing screening (NHS) is the best method for early detection of suspected hearing loss. If the NHS is not universal more than 30% permanent hearing losses are not identified. There are various methods of NHS: otoacoustic emissions (TEOAE, DPOAE) and automatic auditory brainstem response (AABR). After hearing screening, and when hearing loss is suspected, tympanometry and audiological methods then used for determination of hearing threshold; these include ABR, ASSR or/and behavioral methods. The goal of this study is to evaluate the influence of UNHS on the early detection of hearing loss in children before and after the implementation of obligatory universal newborn hearing screening in Slovakia, and also on the etiologic evaluation of hearing impaired infants identified by screening.

METHOD

In Slovakia NHS started in 1998 and was provided in ENT departments. From May 1, 2006 UNHS has been mandatory in Slovakia, using two stages TEOAE in all newborn departments in Slovakia (64 newborn departments). In year 2005--42% of newborns in Slovakia were screened, in 2006--66% newborns and in 2007--94, 99% (three small newborn departments do not yet have equipment for OAE screening). For determination of hearing thresholds ASSR are used in two ENT departments and ABR in the other four ENT departments.

RESULTS

Comparing the number of identified cases with bilateral severe permanent HL or deafness before and after UNHS, 22.8% more cases of PHL were identified in the first year of UNHS. Also the average age of diagnosis of PHL was lower. In the year 2007, 94% of newborns were screened. We found 0.947/1000 newborns with bilateral severe PHL (35.9%) more than before UNHS). After audiologic and etiologic assessment of the 76 infants who failed screening, 5 (6.58%) were found to have normal hearing, 16 (22.54%) had unilateral and 55 (77.46%) had bilateral SNHL. A non-syndromic genetic cause was present in 25.45% of cases, syndromic in 9%, perinatal cause (31%), congenital CMV infection in 7.27%, bilateral cochlear anomalies without other abnormality in 1.83% and unknown etiology in 25.45%.