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.

Is "no response" on diagnostic auditory brainstem response testing an indication for cochlear implantation in children?

OBJECTIVES: To compare the results of a "no response" (NR) result on auditory brainstem response (ABR) testing with those of behavioral pure-tone audiometry and ultimate clinical tracking to cochlear implantation (CI). DESIGN: Retrospective review of pediatric patients who underwent multifrequency ABR testing in a 5 year span. Total of 1143 pediatric patients underwent ABR testing during the study period and 105 (9.2%) were identified with bilateral NR based on absent responses to both click and tone burst stimuli. For the children with NR, various clinical parameters were evaluated as these children progressed through the CI evaluation process. Children were grouped based on whether they underwent ABRs for diagnostic or for confirmatory purposes. RESULTS: Of the 105 children who met inclusion criteria, 94 had sufficient follow-up to be included in this analysis. Ninety-one (96.8%) of 94 children with bilateral NR ABRs were ultimately recommended for and received a CI. Three (3.2%) children were not recommended for implantation based on the presence of multiple comorbidities rather than auditory factors. None of the children (0%) had enough usable residual hearing to preclude CI. For those who had diagnostic ABRs, the average time at ABR testing was 5.4 months (SD 6.2, range 1-36) and the average time from ABR to CI was 10.78 months (SD 5.0, range 3-38). CONCLUSIONS: CI should tentatively be recommended for children with a bilateral NR result with multifrequency ABR, assuming confirmatory results with behavioral audiometric testing. Amplification trials, counseling, and auditory-based intervention therapy should commence but not delay surgical intervention, as it does not appear to change the eventual clinical course. Children not appropriate for this "fast-tracking" to implantation might include those with significant comorbidities, auditory neuropathy spectrum disorder, and unreliable or poorly correlated results on behavioral audiometric testing.

Effects of nonlinear frequency compression on speech identification in children with hearing loss.

OBJECTIVES: This study evaluated effects of nonlinear frequency compression (NLFC) processing in children with hearing loss for consonant identification in quiet and for spondee identification in competing noise or speech. It was predicted that participants would benefit from NLFC for consonant identification in quiet when access to high-frequency information was critical, but that NLFC would be less beneficial, or even detrimental, when identification relied on mid-frequency cues. Further, it was hypothesized that NLFC could result in greater susceptibility to masking in the spondee task. The rationale for these predictions is that improved access to high-frequency information comes at the cost of decreased spectral resolution. DESIGN: A repeated-measures design compared speech-perception outcomes in 17 pediatric hearing aid users (9 to 17 years of age) wearing Naida V SP "laboratory" hearing aids with NLFC on and off. Data were also collected in an initial baseline session in which children wore their personal hearing aids. Children with a wide range of audiometric configurations were included, but all participants were full-time users of hearing aids with active NLFC. For each hearing aid condition, speech perception was assessed in the sound field by using a closed-set 12-alternative consonant-vowel identification measure in quiet, and a closed-set four-alternative spondee-identification measure in a speech-shaped noise or in a two-talker speech masker. RESULTS: No significant differences in performance were observed between laboratory hearing aid conditions with NLFC activated or deactivated for either speech-perception measure. An unexpected finding was that the majority of participants had no difficulty identifying the high-frequency consonant /s/ even when NLFC was deactivated. Investigation into individual differences revealed that subjects with a greater difference in audible bandwidth with NLFC on versus NLFC off were less likely to demonstrate improvements in high-frequency consonant identification in quiet, but were more likely to demonstrate improvements in spondee identification in speech-shaped noise. Group results observed in the initial baseline assessment using personal aids fitted with more aggressive NLFC settings than used in laboratory aids indicated better consonant identification accuracy in quiet. However, spondee identification in the two-talker masker was poorer with personal compared with laboratory hearing aids. Comparisons across personal and laboratory hearing aids are tempered, however, by the potential of an order effect. CONCLUSIONS: The observation of comparable performance with NLFC on and NLFC off in the laboratory aids provides evidence that NLFC is neither detrimental nor advantageous when modest in strength. Results with personal hearing aids fitted with stronger compression settings than laboratory aids (NLFC on) highlight the critical need for further research to determine the impact of NLFC processing on speech perception for a wider range of speech-perception measures and compression settings.

Characteristics of hearing aid fittings in infants and young children.

OBJECTIVES: Hearing aids (HAs) provide the basis for improving audibility and minimizing developmental delays in children with mild to severe hearing loss. Multiple guidelines exist to recommend methods for optimizing amplification in children, but few previous studies have reported HA fitting outcomes for a large group of children. The present study sought to evaluate the proximity of the fitting to prescriptive targets and aided audibility of speech, as well as survey data from pediatric audiologists who provided HAs for the children in the present study. Deviations from prescriptive target were predicted to have a negative impact on aided audibility. In addition, children who were fitted using verification with probe microphone measurements were expected to have smaller deviations from prescriptive targets and greater audibility than cohorts fitted without these measures. DESIGN: HA fitting data from 195 children with mild to severe hearing losses were analyzed as part of a multicenter study evaluating outcomes in children with hearing loss. Proximity of fitting to prescriptive targets was quantified by calculating the average root-mean-square (RMS) error of the fitting compared with Desired Sensation Level prescriptive targets for 500, 1000, 2000, and 4000 Hz. Aided audibility was quantified using the Speech Intelligibility Index. Survey data from the pediatric audiologists who fit amplification for children in the present study were collected to evaluate trends in fitting practices and relate those patterns to proximity of the fitting to prescriptive targets and aided audibility. RESULTS: More than half (55%) of the children in the study had at least 1 ear that deviated from prescriptive targets by more than 5 dB RMS on average. Deviation from prescriptive target was not predicted by pure-tone average, assessment method, or reliability of assessment. Study location was a significant predictor of proximity to prescriptive target with locations that recruited participants who were fit at multiple clinical locations (University of Iowa and Boys Town National Research Hospital) having larger deviations from target than the location where the participants were recruited primarily from a single, large pediatric audiology clinic (University of North Carolina). Fittings based on average real-ear to coupler differences resulted in larger deviations from prescriptive targets than fittings based on individually measured real-ear to coupler differences. Approximately 26% of the children in the study has aided audibility less than 0.65 on the Speech Intelligibility Index (SII). Aided audibility was significantly predicted by the proximity to prescriptive targets and pure-tone average, but not age in months. CONCLUSIONS: Children in the study had a wide range of fitting outcomes in terms of proximity to prescriptive targets (RMS error) and aided speech audibility (SII). Even when recommended HA verification strategies were reported, fittings often exceeded the criteria for both proximity to the prescriptive target and aided audibility. The implications for optimizing amplification for children are also discussed.

Influence of hearing loss on children's identification of spondee words in a speech-shaped noise or a two-talker masker.

OBJECTIVE: This study evaluated the influence of hearing loss on children's speech-perception abilities in a speech-shaped noise or a two-talker masker. For both masker conditions, it was predicted that children with hearing loss would require a more advantageous signal to noise ratio (SNR) than children with normal hearing to achieve the same criterion level of performance. However, it was hypothesized that the performance gap between children with hearing loss and children with normal hearing would be larger in the two-talker than in the speech-shaped noise masker. DESIGN: A repeated-measures design compared the spondee identification performance of two age groups of children with hearing loss (9-11 and 13-17 years of age) and a group of children with normal hearing (9-11 years of age) in continuous speech-shaped noise or a two-talker masker. Estimates of the SNR required for 70.7% correct spondee identification were obtained using an adaptive, four-alternative, forced-choice procedure. Children were tested in the sound field. Children with hearing loss wore their personal hearing aids at their regular settings during testing. RESULTS: Both groups of children with hearing loss performed more poorly than children with normal hearing in the speech-shaped noise masker. Younger children required an additional 2.7 dB SNR and older children required an additional 4.7 dB SNR to achieve the same level of performance as children with normal hearing. This disadvantage decreased to 8.1 dB for both age groups of children with hearing loss in the two-talker masker. For children with hearing loss, degree of hearing loss was significantly correlated with performance in the speech-shaped noise masker, but not in the two-talker masker. CONCLUSIONS: A larger performance gap was observed between children with hearing loss and children with normal hearing in competing speech than in steady state noise. These results are consistent with the hypothesis that hearing loss influenced children's perceptual processing abilities.

Effects of age and hearing impairment on the ability to benefit from temporal and spectral modulation.

OBJECTIVES: At poor signal-to-noise ratios, speech understanding may depend on the ability to combine speech fragments that are distributed across time and frequency. The goal of this study was to determine the effects of development and hearing impairment on this ability. DESIGN: Listeners in the present study included adults and children with normal hearing and with hearing impairment. The children with normal hearing included a younger group (aged 4.6-6.9 yr, N = 10) and an older group (aged 7.3-11.1 yr, N = 11). The adults with normal hearing were aged 19 to 27 yr (N = 10). Adults (aged 19-54 yr, N = 9) and children (aged 7.2-10.7 yr, N = 8) with hearing impairment were also tested. The two groups with hearing impairment had comparable mild/moderate bilateral sensorineural hearing impairment. Masked speech reception thresholds for sentences were determined in a baseline condition of steady speech-shaped noise and in noise that was temporally modulated, spectrally modulated, or both temporally and spectrally modulated. RESULTS: The results of normal-hearing listeners indicated higher masked speech reception thresholds for children than adults in steady noise. Adults and children showed the same magnitude of masking release for spectral modulation. Adults showed more masking release than the younger children for temporal modulation and showed more masking release than both the younger and older children for combined temporal/spectral modulation. Comparing normal-hearing and hearing-impaired listeners, the hearing-impaired listeners had higher masked speech reception thresholds in the steady noise condition and reduced masking release in the modulated noise conditions. Neither the two-way interaction between age and hearing impairment nor the three-way interaction between age, hearing impairment, and masking configuration was significant. CONCLUSIONS: Although the reduced masking release for temporal modulation shown by the younger children with normal hearing could be a result of poor temporal resolution, it more likely reflects inefficient use of speech cues in temporal gaps or factors stemming from higher signal-to-noise ratios required by children in the baseline condition. The reduced masking release for combined temporal/spectral modulation demonstrated by both the younger and older children with normal hearing may indicate that children in the age range tested here have some difficulty in combining speech information that is distributed across temporal and spectral gaps. Hearing impairment was associated with higher thresholds and reduced masking release in all modulation conditions. Children with hearing impairment showed the poorest performance of any group, consistent with additive effects of hearing loss and development.

Effects of frequency compression hearing aids for unilaterally implanted children with acoustically amplified residual hearing in the nonimplanted ear.

OBJECTIVES: The primary objective of this study is to evaluate the benefits of nonlinear frequency compression (NLFC) hearing aids in the nonimplanted ears of children with unilateral cochlear implants (CIs). It is hypothesized that speech perception performance will benefit from complementary auditory cues provided by the CI and the hearing aid, particularly with the increased access to high-frequency sounds provided by NLFC. DESIGN: Eleven children using unilateral CIs with usable residual hearing in the nonimplanted ears were enrolled in the study and fitted with NLFC hearing aids. The test protocol included consonant-nucleus-consonant words in quiet, the Hearing in Noise Test sentences presented in speech noise and two-talker maskers, and a consonant identification task. Subjects were tested in a CI-alone condition as well as bimodally, with and without NLFC enabled. RESULTS: The results support previous work in adults and children, demonstrating the beneficial effects of bimodal listening. Frequency compression did not significantly affect performance for the children enrolled in this study, although some preferred using NLFC. The results yield suggestions regarding test methods for pediatric bimodal listeners, and considerations regarding validation and audibility of the compressed signal. CONCLUSIONS: Hearing aid use in the contralateral ear of unilaterally implanted children is beneficial. Children and young adults who are fitted bimodally should be tested both in quiet and in complex listening situations to determine bimodal benefit. In the current test battery, the inclusion of frequency compression in the hearing aid fitting does not seem to provide significant improvement beyond standard hearing aid fittings or any bilateral interference symptoms for this group of bimodal listeners.

Cochlear implantation in children with auditory neuropathy spectrum disorder.

OBJECTIVE: To report the patient's characteristics, preoperative audiological profiles, surgical outcomes, and postoperative performance for children with auditory neuropathy spectrum disorder (ANSD) who ultimately received cochlear implants (CIs). DESIGN: Prospective, longitudinal study of children with ANSD who received CIs after a stepwise management protocol that included electrophysiologic and medical assessment, documentation of behavioral audiometric thresholds and subsequent fitting of amplification according to Desired Sensation Level targets, auditory-based intervention with careful monitoring of skills development and communication milestones, and finally implantation when progress with the use of acoustic amplification was insufficient. RESULTS: Of 140 children with ANSD, 52 (37%) received CIs in their affected ears (mean duration of use of 41 mos). Many of these children were born prematurely (42%) and impacted by a variety of medical comorbidities. More than one third (38%) had abnormal findings on preoperative magnetic resonance imaging of the brain and inner ear, and 81% had a greater than severe (>70 dB HL) degree of hearing loss before implantation. Although 50% of the implanted children with ANSD demonstrated open-set speech perception abilities after implantation, nearly 30% of them with >6 months of implant experience were unable to participate in this type of testing because of their young age or developmental delays. No child with cochlear nerve deficiency (CND) in their implanted ear achieved open-set speech perception abilities. In a subgroup of children, good open-set speech perception skills were associated with robust responses elicited on electrical-evoked intracochlear compound action potential testing when this assessment was possible. CONCLUSIONS: This report shows that children with ANSD who receive CIs are a heterogeneous group with a wide variety of impairments. Although many of these children may ultimately benefit from implantation, some will not, presumably because of a lack of electrical-induced neural synchronization, the detrimental effects of their other associated conditions, or a combination of factors. When preoperative magnetic resonance imaging reveals central nervous system pathology, this portends a poor prognosis for the development of open-set speech perception, particularly when CND is evident. These results also show that electrical-evoked intracochlear compound action potential testing may help identify those children who will develop good open-set speech perception. Instead of recommending CI for all children with electrophysiologic evidence of ANSD, the stepwise management procedure described herein allows for the identification of children who may benefit from amplification, those who are appropriate candidates for cochlear implantation, and those who, because of bilateral CND, may not be appropriate candidates for either intervention.

Protocol for Rapid, Accurate, Electrophysiologic, Auditory Assessment of Infants and Toddlers.

BACKGROUND: Audiologists often lack confidence in results produced by current protocols for diagnostic electrophysiologic testing of infants. This leads to repeat testing appointments and slow protocols which extend the time needed to complete the testing and consequently delay fitting of amplification. A recent publication (Sininger et al50) has shown how new technologies can be applied to electrophysiologic testing systems to improve confidence in results and allow faster test protocols. Average test times for complete audiogram predictions when using new technologies and protocols were found to be just over 32 minutes using auditory brainstem response (ABR) and just under 20 minutes using auditory steady-state response (ASSR) technology. PURPOSE: The purpose of this manuscript is to provide details of expedited test protocols for infant and toddler diagnostic electrophysiologic testing. SUMMARY: Several new technologies and their role in test speed and confidence are described including CE-Chirp stimuli, automated detection of ABRs using a technique called F MP, Bayesian weighting which is an alternative to standard artifact rejection and Next-Generation ASSR with improved response detection and chirp stimuli. The test protocol has the following features: (1) preliminary testing includes impedance measures and otoacoustic emissions, (2) starting test levels are based on Broad-Band CE-Chirp thresholds in each ear, (3) ABRs or ASSRs are considered present based on automated detection rather than on replication of responses, (4) number of test levels is minimized, (5) ASSR generally evaluates four frequencies in each ear simultaneously with flexibility to change all test levels independently. CONCLUSIONS: Combining new technologies with common-sense strategies has been shown to substantially reduce test times for predicting audiometric thresholds in infants and toddlers (Sininger et al50). Details and rationales for changing test strategies and protocols are given and case examples are used to illustrate.

Internal auditory canal morphology in children with cochlear nerve deficiency.

OBJECTIVE: To describe the internal auditory canal (IAC) and inner ear morphologic characteristics of children with cochlear nerve (CN) deficiency. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution magnetic resonance imaging (MRI). INTERVENTIONS: MRI of the brain. Clinical evaluation. MAIN OUTCOME MEASURES: Review of medical records, audiological testing results, and imaging studies. Images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs and inner ears. Audiometric thresholds were evaluated in all subjects. METHODS: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution MRI. A review of the medical records, audiologic testing results, and imaging studies was undertaken. The images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs, and inner ears. The audiometric thresholds were evaluated in all subjects. RESULTS: Among the 14 patients, 5 had known syndromes. MRI allowed an exact specification of the nervous structures within all ears with normal-size IACs. Precise characterization of the nerves in ears with small IACs was more difficult, requiring a consideration of both imaging findings and functional parameters. Five children had bilateral deficient CNs, whereas the remaining 9 subjects were affected unilaterally. Thus, 19 ears had CN deficiency (absent CN, 16; small CN, 3). Eleven ears had normal-size IACs and deficient CNs. Of the 9 ears with small IACs, 8 had deficient CNs (absent, 7; small, 1) on the basis of both MRI and functional assessments. Two ears with small IACs had clear morphologic and/or functional evidence for the presence of a CN: one had a small-size CN on MRI, whereas another had a single nerve in a small IAC with present facial and auditory functions. CONCLUSION: The findings of this study suggest that CN deficiency is not an uncommon cause of congenital hearing loss. The findings that most ears with CN deficiency had normal IAC morphology and that two ears with small IACs had CNs present indicate that IAC morphology is an unreliable surrogate marker of CN integrity. On the basis of these findings, we think that high-resolution MRI, rather than CT imaging, should be performed in all cases of pediatric hearing loss, especially in those cases where profound hearing loss has been documented. For ears with small IACs, the resolution of MRI currently remains limiting. In these cases, the determination of CN status frequently requires a variety of anatomic (CT and MRI) and functional tests (auditory brainstem response, otoacoustic emissions, behavioral audiometry, and physical examination).

Cochlear implantation in children with labyrinthine anomalies and cochlear nerve deficiency: implications for auditory brainstem implantation.

OBJECTIVES/HYPOTHESIS: Compare outcomes among children with inner ear malformations and/or cochlear nerve deficiency (CND) who have received a cochlear implant (CI). STUDY DESIGN: Individual retrospective cohort study from 1993 to 2010. METHODS: A select cohort of 76 children was identified. Imaging characteristics, operative findings, complications, mapping parameters, and performance were assessed. Comparisons among the different groups were undertaken. RESULTS: Surgery was mostly uncomplicated. Nearly all children demonstrated behavioral responses to CI stimulation irrespective of inner ear morphology or the presence of CND. Children with CND had higher pure tone averages (PTAs) and required greater charge for stimulation than other malformation types. Open-set speech perception was achieved in 100% of children with incomplete partition-enlarged vestibular aqueduct (IP-EVA), 50% of those with hypoplastic malformations, and 19% of CND cases. Robust responses on eighth nerve compound action potential (ECAP) testing through the implant was associated with higher levels of speech perception. Manually supplemented communication strategies were more common among children with hypoplastic malformations (69%) and CND (95%) than those with IP-EVA (18%). CONCLUSIONS: Children with IP-EVA malformations have an excellent prognosis for developing open-set speech perception and using oral communication modes following CI. On the contrary, children with severe malformations or CND may have elevated charge requirements for attaining sound detection alone. These children's prognosis for obtaining open-set speech understanding, using exclusive oral communication, and participating in mainstream education is more limited. These findings have important implications for considering alternative forms of intervention such as auditory brainstem implantation and/or supplementation with visually based communication strategies.

Auditory neuropathy characteristics in children with cochlear nerve deficiency.

OBJECTIVE: To describe a group of children exhibiting electrophysiologic responses characteristic of auditory neuropathy (AN) who were subsequently identified as having absent or small cochlear nerves (i.e., cochlear nerve deficiency). DESIGN: A retrospective review of the clinical records, audiological testing results, and magnetic resonance imaging (MRI) studies. Fifty-one of 65 children with AN characteristics on auditory brain stem response (ABR) testing had MRI available for review. Nine (18%) of these 51 children with ABR characteristic of AN have been identified as having small (N = 2; 4%) or absent (N = 7; 14%) cochlear nerves on MRI. RESULTS: Of the nine children with cochlear nerve deficiency, five (56%) were affected unilaterally and four (44%) bilaterally. Eight of nine presented after failing a newborn infant hearing screening, whereas one presented at 3 yr of age. On diagnostic ABR testing, all 9 children (9 of 13 affected ears; 69%) had evidence of a cochlear microphonic (CM) and absent neural responses in at least one ear. In the unilateral cases, AN characteristics were detected in all affected ears. In bilateral cases, at least one of the ears in each child demonstrated the AN phenotype, whereas the contralateral ear had no CM identified. Only one ear with cochlear nerve deficiency had present otoacoustic emissions as measured by distortion-product otoacoustic emissions. In children with appropriate available behavioral testing results, all ears without cochlear nerves were identified as having a profound hearing loss. Only 4 (31%) of the 13 ears with cochlear nerve deficiency had a small internal auditory canal on MRI. CONCLUSIONS: Children with cochlear nerve deficiency can present with electrophysiologic evidence of AN. These children frequently refer on newborn screening examinations that use ABR-based testing methods. Similar to other causes of AN, diagnostic ABR testing will show a CM with absent neural responses. Given that 9 (18%) of 51 children with available MRI and electrophysiologic characteristics of AN in our program have been identified as having cochlear nerve deficiency makes this a relatively common diagnosis. These findings suggest that MRI is indicated for all children diagnosed with AN. Moreover, electrophysiologic evidence of unilateral AN in association with a profound hearing loss should make the clinician highly suspicious for this problem. Although children with cochlear nerve deficiency who have a small nerve may benefit from cochlear implantation or amplification, these interventions are obviously contraindicated in children with completely absent cochlear nerves.