Comparisons of Auditory Steady State Response and Behavioral Air Conduction and Bone Conduction Thresholds for Infants and Adults With Normal Hearing

Dealing with correlations in the multichannel EEG using bipolar derivations and Monte Carlo simulations: application to the detection of auditory steady-state responses

The multichannel objective response detection (MORD) techniques are statistical methods, which use information from more than one electroencephalography (EEG) channel, to infer the presence of evoked potential. However, the correlation level between the channels can lead to a decrease in MORD performance, such as an increase in the false positive (FP) rate and/or a decrease in the detection rate (DR). The present study aims to propose a method to deal with the correlations in the multichannel EEG. The method consists of making an adjustment in the Monte Carlo simulation, considering the information between channels. The MORD techniques with and without the new method were applied to an auditory steady-state response (ASSR) database, composed of the EEG multichannel of eleven volunteers during multifrequency stimulation. The proposed method kept the FP rate at values equal to or less than the significance level of the test and led to an increase of 8.51% in the DR in relation to non-application of the method. Results of this study indicate that the proposed method is an alternative to deal with the effect of the correlation between channels in situations where MORD techniques are applied.

Automatic audiometry using auditory steady-state response and sequential test strategy applied to volunteers with normal hearing

PURPOSE

In the present study, a new procedure to perform automatic audiometry using multifrequency Auditory Steady-State Response (ASSR) is proposed.

METHODS

The automatic audiometry procedure consists of detecting the presence of multifrequency ASSR in real-time using the sequential test strategy and by adjusting the stimulus intensity independently. The ASSR audiometric thresholds of 18 adult volunteers with normal hearing were determined by automatically (four simultaneous frequencies per ear) at modulation frequencies in the 80 Hz range. The exam time and the difference between ASSR thresholds and pure-tone behavioural hearing thresholds were estimated as performance measures.

RESULTS

The results showed that automatic audiometry can reduce the number of intensity levels used to obtain the ASSR threshold by up to 58% when compared to audiometry without using the techniques applied in automatic audiometry. In addition, the average of the difference between ASSR thresholds and Pure-Tone Behavioural Hearing thresholds was around 19 dB, which is similar to the results reported in similar studies.

CONCLUSIONS

The audiometric procedure proposed in this study is fully automatic, i.e., does not require any human supervision throughout the exam, and is able to significantly reduce the conventional exam time.

Comparison of Auditory Steady-State Responses With Conventional Audiometry in Older Adults

Behavioral measures, such as pure-tone audiometry (PTA), are commonly used to determine hearing thresholds, however, PTA does not always provide reliable hearing information in difficult to test individuals. Therefore, objective measures of hearing sensitivity that require little-to-no active participation from an individual are needed to facilitate the detection and treatment of hearing loss in difficult to test people. Investigation of the reliability of the auditory steady-state response (ASSR) for measuring hearing thresholds in older adults is limited. This study aimed to investigate if ASSR can be a reliable, objective measure of frequency specific hearing thresholds in older adults. Hearing thresholds were tested at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz in 50 participants aged between 60 and 85 years old, using automated PTA and ASSR. Hearing thresholds obtained from PTA and ASSR were found to be significantly correlated (p < .001) in a cohort consisting of participants with normal hearing or mild hearing loss. ASSR thresholds were significantly higher as compared to PTA thresholds, but for the majority of cases the difference remained within the clinically acceptable range (15 dB). This study provides some evidence to suggest that ASSR can be a valuable tool for estimating objective frequency-specific hearing thresholds in older adults and indicate that ASSR could be useful in creating hearing treatment plans for older adults who are unable to complete behavioral PTA. Further research on older adults is required to improve the methodological features of ASSR to increase consistency and reliability, as well as minimize some of the limitations associated with this technique.

Acoustic Change Complex and Visually Reinforced Infant Speech Discrimination Measures of Vowel Contrast Detection

OBJECTIVES

To measure the effect of stimulus rate and vowel change direction on the acoustic change complex (ACC) latencies and amplitudes and compare ACC metrics to behavioral measures of vowel contrast detection for infants tested under the age of 1 year. We tested the hypothesis that the direction of spectral energy shift from a vowel change would result in differences in the ACC, owing to the sensitivity of cortical neurons to the direction of frequency change. We evaluated the effect of the stimulus rate (1/s versus 2/s) on the infants' ACC. We evaluated the ACC amplitude ratio's sensitivity (proportion of ACCs present for each change trial) and compared it to perceptual responses obtained using a visually reinforced infant speech discrimination paradigm (VRISD). This report provides normative data from infants for the ACC toward the ultimate goal of developing a clinically useful index of neural capacity for vowel discrimination.

DESIGN

Twenty-nine infants, nine females, 4.0 to 11.8 months of age, participated. All participants were born at full term and passed their newborn hearing screens. None had risk factors for hearing or neurologic impairment. Cortical auditory evoked potentials were obtained in response to synthesized vowel tokens /a/, /i/, /o/, and /u/ presented at a rate of 1- or 2/s in an oddball stimulus paradigm with a 25% probability of the deviant stimulus. All combinations of vowel tokens were tested at the two rates. The ACC was obtained in response to the deviant stimulus. The infants were also tested for vowel contrast detection using a VRISD paradigm with the same combinations of vowel tokens used for the ACC. The mean age at the time of the ACC test was 5.4 months, while the mean age at the behavioral test was 6.8 months.

RESULTS

Variations in ACC amplitude and latency occurred as a function of the initial vowel token and the contrast token. However, the hypothesis that the direction of vowel (spectral) change would result in significantly larger change responses for high-to-low spectral changes was not supported. The contrasts with /a/ as the leading vowel of the contrast pair resulted in the largest ACC amplitudes than other conditions. Significant differences in the ACC presence and amplitude were observed as a function of rate, with 2/s resulting in ACCs with the largest amplitude ratios. Latency effects of vowel contrast and rate were present, but not systematic. The ACC amplitude ratio's sensitivity for detecting a vowel contrast was greater for the 2/s rate than the 1/s rate. For an amplitude ratio criterion of ≥1.5, the sensitivity was 93% for ACC component P2-N2 at 2/s, whereas at 1/s sensitivity was 70%. VRISD tests of vowel-contrast detection had a 71% hit and a 21% false-positive rate. Many infants who could not reach performance criteria for VRISD had ACC amplitude ratios of ≥2.0.

CONCLUSIONS

The ACC for vowel contrasts presented at a rate of 2/s is a robust index of vowel-contrast detection when obtained in typically developing infants under the age of 1 year. The ACC is present in over 90% of infants tested at this rate when an amplitude ratio criterion of ≥1.5 is used to define a response. The amplitude ratio appears to be a sensitive metric for the difference between a control and contrast condition. The ACC can be obtained in infants who do not yet exhibit valid behavioral responses for vowel change contrasts and may be useful for estimating neural capacity for discriminating these sounds.

Multichannel search strategy for improving the detection of auditory steady-state response

Auditory steady-state response (ASSR) is useful for hearing threshold estimation. The ASSR is usually detected with objective response detectors (ORD). The performance of these detectors depends on the signal-to-noise ratio (SNR) as well as the signal length. Since it is undesirable to increase the signal length, then, this work provides a multivariate technique for improving the SNR and consequently the detection power. We propose the insertion of a short calibration step before the detection protocol, in order to perform a search among the available electroencephalogram (EEG) derivations and select the derivation with the highest SNR. The ORD used in this work was the magnitude-squared coherence (MSC). The standard detection protocol is to use the same EEG derivation in all exams. Using 22-scalp positions, the new technique achieved a detection rate higher than that obtained in 99.13% of the standard detection protocol. When restrictions were applied to the search, a superior performance was achieved. Thus, the technique proposed was able to track the best EEG derivations before exams and seems to be able to deal with the variability between individuals and between sessions.

Effective Masking Levels for Bone Conduction Auditory Brainstem Response Stimuli in Infants and Adults with Normal Hearing

OBJECTIVE

The purpose of the present study was to investigate effective masking levels (EMLs) for bone conduction (BC) auditory brainstem response (ABR) testing in infants and adults. Early hearing detection and intervention programs aim to limit delays in identifying ear-specific type/degree of hearing loss in infants using the ABR. Ear-specific assessment poses challenges as sound delivered to one ear can travel across the skull and activate the contralateral cochlea. Wave V amplitude and latency measures ipsilateral and contralateral to the bone oscillator can be compared to isolate the test cochlea in some cases; however, when these findings are equivocal, clinical masking is required. This study aims to determine EMLs for ABRs elicited to 500- and 2000-Hz BC stimuli for normal-hearing infants (0 to 18 months) and adults.

DESIGN

Participants were 21 adults (18 to 54 years) and 24 infants (5 to 47 weeks) with normal hearing. BC 500- and 2000-Hz brief tonal stimuli at intensities approximating normal levels were presented via a B-71 oscillator (infants: 20 dB nHL at 500 Hz and 30 dB nHL at 2000 Hz; adults: 500 and 2000 Hz at 20 and 30 dB nHL, respectively). White noise masking was presented binaurally via ER-3A earphones (22 to 82 dB SPL; 10-dB steps). The lowest level of masking to eliminate a BC response was deemed the EML.

RESULTS

For stimuli presented at 20 dB nHL, adult mean (1 SD) EMLs for 500 and 2000 Hz were 65 (9) and 53 (6) dB SPL, respectively. Mean EMLs for infants were 80 (6) dB SPL for 500 Hz at 20 dB nHL and 64 (9) dB SPL for 2000 Hz at 30 dB nHL. Compared to adults, infants required approximately 13 dB more masking at 500 Hz but a similar amount of masking at 2000 Hz. Infants required 26 dB more masking at 500 versus 2000 Hz, whereas, adults required only 12 dB more masking.

CONCLUSIONS

Maximum binaural EMLs for infant BC responses elicited to 500 Hz at 20 dB nHL are 82 dB SPL, and for 2000 Hz at 30 and 40 dB nHL, respectively, are 72 and 82 dB SPL. Monaural masking levels for the nontest ear (assuming 10 dB of interaural attenuation) recommended clinically are as follows: (1) 500 Hz: 72 and 82 dB SPL at 20 and 30 dB nHL, respectively; and (2) 2000 Hz: 62, 72, and 82 dB SPL at 30, 40, and 50 dB nHL, respectively. Unsafe levels of white noise would be needed to effectively mask at greater stimulus levels.

Automated analysis of bone-conduction cortical auditory evoked potential in normal-hearing neonates

Introduction

The cortical auditory evoked potential allows the possibility of objectively evaluating the entire auditory system, which is desirable in the pediatric population. Bone conduction auditory stimulation is recommended in the differential diagnosis of conductive hearing loss. However, there are not many studies of cortical auditory evoked potential using bone conduction.

Objective

The aim of this study was to characterize the response of cortical auditory evoked potential through bone conduction in normal-hearing neonates using an automated response analysis equipment.

Methods

This study included 30 normal-hearing neonates, without risk factors for hearing loss. The equipment used was the HEARlab automated response analysis and the cortical responses were evaluated at the frequencies of 500–4000 Hz through bone conduction, at intensity ranging from 0 to 60 dBnHL. The latencies and amplitudes were manually marked by experienced judges.

Results

Cortical auditory evoked potential responses were detected in 100% of the evaluated subjects and there was no difference regarding the cortical response of the neonates in relation to the variables of gender, ear and masking use. At an intensity of 60 dBnHL for the frequencies of 500, 1000, 2000 and 4000 Hz the latencies were 234; 241; 239 and 253 ms and the amplitudes were 15.6; 8.4; 6.2; 6.3 μV. The mean thresholds were 23.6; 28; 31 and 33.1 dBnHL, respectively.

Conclusion

It was possible to measure the cortical auditory evoked potential response in the neonatal population using bone vibrator as sound transducer and to draw the profile of the cortical auditory evoked potential latencies and amplitudes by frequencies at the intensity of 60 dBnHL and at the threshold.

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.

Visual Reinforcement Audiometry and Steady-State Auditory Evoked Potential in infants with and without conductive impairment

ABSTRACT Purpose: to compare the findings of minimum levels of answers through air and bone conductions between the Visual Reinforcement Audiometry and the Steady-State Auditory Evoked Potential in infants from six to twelve months, with and without conductive disorder. Methods: sixty children aged six to twelve months were evaluated, 30 presenting conductive disorder, and 30 not presenting it. Children with malformation in the external auditory meatus with neurological alteration and / or genetic syndrome were excluded, as well as patients with sensorineural or mixed hearing loss. The infants were subjected to Visual Reinforcement Audiometry and Steady-State Auditory Evoked Potential evaluation through air and bone conduction on the same day. The results of both assessments were compared and correlated. Results: in the comparison through air conduction, for the group without conductive disorder of the medium ear, the minimum levels of response for 500 and 1000Hz were lower (better thresholds) for Steady-State Auditory Evoked Potential in both ears, and through bone conduction were very similar in all frequencies. Concerning the infants that present conductive disorder, the responses through air conduction were better in all frequencies evaluated when obtained via Steady-State Auditory Evoked Potential test. Through bone conduction, the results were very similar for both groups. Conclusion: it was possible to compare the findings to the minimum levels of response through air and bone conductions between the Visual Reinforcement Audiometry and the Steady-State Auditory Evoked Potential, being that the comparison for bone conduction in both groups presents an equivalence in the results, being very similar. In addition, for the air conduction, in the control group, there was proximity of responses of some frequencies, while the values for the Steady-State Auditory Evoked Potential test were better than the behavioral responses in the conductive disorder group.

Intraoperative auditory steady-state monitoring during surgery in the cerebellopontine angle for estimation of postoperative hearing classes

OBJECTIVE Brainstem auditory evoked potentials (BAEPs) have been used for intraoperative monitoring of the auditory nerve for many years. However, BAEPs yield limited information about the expected postoperative hearing quality and speech perception. The auditory steady-state response (ASSR) enables objective audiograms to be obtained in patients under anesthesia. These ASSRs could be used for intraoperative estimation of hearing classes to improve the postoperative outcome and quality of life. Studies investigating the clinical use of ASSRs during total intravenous anesthesia are currently lacking. The work presented in this article therefore investigates the application of ASSRs for intraoperative estimation of hearing classes. METHODS In 43 patients undergoing surgery for vestibular schwannoma, ASSR measurements were performed at the beginning and end of the surgical procedure. ASSR stimuli consisted of 80-dB hearing level amplitude-modulated tones with 5-minute duration, 90-Hz modulation, and 3 different carrier frequencies: 500, 1000, and 2000 Hz. Stimulation was performed unilaterally with and without contralateral masking, using single and combined carriers. Evoked responses were recorded and analyzed in the frequency domain. ASSRs were compared with extraoperative hearing classes and BAEPs using ANOVA, correlation, and receiver operating characteristic statistics. RESULTS ASSRs yielded high and consistent area under the curve (AUC) values (mean 0.83) and correlation values (mean -0.63), indicating reliable prediction of hearing classes. Analysis of BAEP amplitude changes showed lower AUC (mean 0.79) and correlation values (0.63, 0.37, and 0.50 for Waves I, III, and V, respectively). Latencies showed low AUC values (mean 0.6) and no significant correlation. Combination of several carriers for simultaneous evaluation reduced ASSR amplitudes and respective AUC values. Contralateral masking did not show a significant effect. CONCLUSIONS ASSRs robustly estimate hearing class in patients under total intravenous anesthesia, even when using short measurement durations. The method provides a diagnostic performance that exceeds conventional BAEP monitoring and enables objective and automated evaluation. On the basis of these findings, continuous intraoperative auditory monitoring could become a promising alternative or adjunct to BAEPs.