Trends in Performance Using Early Speech Perception Test in Typically Developing Tamil-Speaking Children.

BACKGROUND AND OBJECTIVES: The study attempted to trace age-related changes in speech perception in typically developing children (≥3 to ≤6 years) using the "Early Speech Perception (ESP)" in Tamil. The test was developed in line with the original English version of ESP but adapted to suit the linguistic requirement of the Tamil language. SUBJECTS AND METHODS: Using a cross-sectional design, the test was administered to 205 children with normal hearing who were classified into three age groups (≥3 to ≤4, >4 to ≤5, and >5 to ≤6 years). The developed test had three subtests (syllable categorization, bisyllable word identification, and trisyllable word identification). RESULTS: All three age groups obtained perfect or near-perfect scores on the three subtests of ESP. There was no significant difference observed between the two adjacent age groups (≥3 to ≤4 vs. >4 to ≤5 years, >4 to ≤5 vs. >5 to ≤6 years) for all three subtests. However, significant differences were seen only between the youngest and the oldest age groups for the three subtests (≥3 to ≤4 vs. >5 to ≤6 years). CONCLUSIONS: The results indicated that ESP in Tamil can be performed effectively in all the three age groups studied.

Relation Between the Screening Checklist for Auditory Processing in Adults and Diagnostic Auditory Processing Test Performance.

Purpose The aim of the study was to evaluate the relationship between the Screening Checklist for Auditory Processing in Adults and the performance of older adults on a battery of diagnostic tests for auditory processing. This was done for two versions of the checklist, one answered by older individuals at risk for auditory processing disorder (APD) and the other by the family of the older adults. Method Forty-nine older adults and 34 of their family members were initially tested with the screening checklist, each being tested with the version developed for them. Approximately half of the older adults had normal pure-tone thresholds, while the others had mild-moderate hearing loss above 2 kHz. The older adults were administered tests of auditory separation/closure, auditory integration, temporal resolution, temporal patterning, and auditory memory and sequencing. Results Most of the older adults and their family members reported of the presence of auditory processing difficulties on the screening checklist. On the diagnostic test battery, many of the older adults, irrespective of their high-frequency hearing sensitivity, failed the tests measuring temporal resolution and auditory integration. The sensitivity and specificity of the checklist answered by the older individuals were 69.05% and 71.43%, respectively. On the other hand, for the checklist answered by the family members, it was 77.78% and 33.33%, respectively. The test-retest reliability of the two versions of the checklist was found to be good. Conclusions As the specificity of the checklist answered by the family members was considerably lower than that answered by the older adults, the use of the version for the latter group is recommended. However, the checklist answered by the caregivers could be used to complement information obtained from the older adults at risk for APD when the older adults are unable to give valid responses.

Comparison of Relative Loudness Judgment in Children using Listening Devices with Typically Developing Children.

Introduction Loudness perception is considered important for the perception of emotions, relative distance and stress patterns. However, certain digital hearing devices worn by those with hearing impairment may affect their loudness perception. This could happen in devices that have compression circuits to make loud sounds soft and soft sounds loud. These devices could hamper children from gaining knowledge about loudness of acoustical signals. Objective To compare relative loudness judgment of children using listening devices with age-matched typically developing children. Methods The relative loudness judgment of sounds created by day-to-day objects were evaluated on 60 children (20 normal-hearing, 20 hearing aid users, & 20 cochlear implant users), utilizing a standard group comparison design. Using a two-alternate forced-choice technique, the children were required to select picturized sound sources that were louder. Results The majority of the participants obtained good scores and poorer scores were mainly obtained by children using cochlear implants. The cochlear implant users obtained significantly lower scores than the normal-hearing participants. However, the scores were not significantly different between the normal-hearing children and the hearing aid users as well as between the two groups with hearing impairment. Conclusion Thus, despite loudness being altered by listening devices, children using non-linear hearing aids or cochlear implants are able to develop relative loudness judgment for acoustic stimuli. However, loudness growth for electrical stimuli needs to be studied.

Relation between auditory memory and global memory in young and older adults.

PURPOSE: Controversy exists as to whether auditory memory is modality-specific or not. To determine this, the study investigated the relation between the scores obtained on an auditory memory test with that obtained on a global memory test in adults. The study also aimed to compare the scores of young and older adults on the two memory tests. METHODS: Thirty young adults aged 18 to 30 years and 30 older adults aged 58 to 70 years, having normal hearing sensitivity, were studied. Auditory memory was evaluated using the 'Kannada auditory memory and sequencing test', while global memory was assessed using the memory domain of the 'Cognitive linguistic assessment protocol for Adults' and the 'Memory ability checklist'. RESULTS: No significant correlation was seen between the scores obtained on the auditory memory and the global memory tests in both young adults as well as older adults. Also, the scores on the memory ability checklist did not show any correlation with either global memory scores or auditory memory scores in both participant groups. Additionally, the scores of the three memory measures were found to be significantly different from each other. The older adults obtained significantly poorer scores on all three memory tools compared to young adults. CONCLUSION: The findings indicated that auditory memory is modality-specific and is independent of global memory. Additionally, all three measures were sensitive in detecting age-related decline in memory.

Comparison of Relative Loudness Judgment in Children using Listening Devices with Typically Developing Children

Abstract Introduction Loudness perception is considered important for the perception of emotions, relative distance and stress patterns. However, certain digital hearing devices worn by those with hearing impairment may affect their loudness perception. This could happen in devices that have compression circuits to make loud sounds soft and soft sounds loud. These devices could hamper children from gaining knowledge about loudness of acoustical signals. Objective To compare relative loudness judgment of children using listening devices with age-matched typically developing children. Methods The relative loudness judgment of sounds created by day-to-day objects were evaluated on 60 children (20 normal-hearing, 20 hearing aid users, & 20 cochlear implant users), utilizing a standard group comparison design. Using a two-alternate forced-choice technique, the children were required to select picturized sound sources that were louder. Results The majority of the participants obtained good scores and poorer scores were mainly obtained by children using cochlear implants. The cochlear implant users obtained significantly lower scores than the normal-hearing participants. However, the scores were not significantly different between the normal-hearing children and the hearing aid users as well as between the two groups with hearing impairment. Conclusion Thus, despite loudness being altered by listening devices, children using non-linear hearing aids or cochlear implants are able to develop relative loudness judgment for acoustic stimuli. However, loudness growth for electrical stimuli needs to be studied.

Comparison of Diagnostic Auditory Processing Test Scores Measured in Clinical and School Settings.

Purpose The study aimed to compare auditory processing and cognitive test scores measured in a clinical setting with that measured in a school setting using a repeated-measures design. This was done on typically developing children and children with auditory processing disorder (APD). Method Thirty-two children (16 typically developing and 16 with APD), aged 7 years, were evaluated using three diagnostic auditory processing tests and a cognitive test. The tests included the Speech Perception in Noise Test in Kannada, the Gap Detection Threshold Test, the Dichotic Consonant-Vowel Test, and the Auditory Memory and Sequencing Test in Kannada. All the children were evaluated in an audiological diagnostic setting, as well as in their school. Results No significant difference in scores was obtained in the two settings for all the four tests that were administered. This was seen in the typically developing children and the children with APD. Additionally, the pass/fail decision for each test did not alter in the two settings. Moderate to almost perfect agreement was seen between the tests carried out in the two settings in both groups, on a Kappa test of agreement. In both settings, the children with APD performed significantly poorer than the typically developing children on the four diagnostic tests. Conclusions The findings of the study indicate that the diagnostic auditory processing tests and the cognitive test can be carried out in school settings as effectively as tests carried out in an audiological diagnostic clinical setting. This will enable carrying out diagnostic tests on children in schools soon after they are referred on screening auditory processing tools, administered in the educational setting. This will prevent missing diagnosis of children who fail to report to a diagnostic audiological center for detailed auditory processing evaluation.

Comparison of Intensity Discrimination between Children Using Cochlear Implants and Typically Developing Children.

OBJECTIVES: Differential sensitivity of intensity is known to be important for the perception of the relative distance of sounds in the environment, emotions of speakers, and localize sounds. However, a few features in listening devices, such as cochlear implants, used by individuals with hearing loss alter the output intensity heard by them. This makes soft sounds loud and loud sounds soft. Hence, the aim of the present study was to compare the intensity discrimination of children using cochlear implants with that of typically developing children. MATERIALS AND METHODS: Intensity discrimination of 30 children (15 using cochlear implants and 15 typically developing children) was obtained for three warble tones (500 Hz, 1000 Hz, and 4000 Hz) and three vowels (/a/, /i/, and /u/). The responses of the two participant groups, obtained using a 3-alternative forced-choice technique, were compared. RESULTS: Children using cochlear implants performed significantly poorer than typically developing children for the 4000 Hz warble tone and for the vowels /a/ and /u/. However, there was no significant difference for the remaining stimuli. CONCLUSION: The study indicated that the intensity discrimination threshold varies as a function of the frequency of the signals in children using cochlear implants. Intensity discrimination for high-frequency tones was significantly poorer for typically developing children, but not for low-frequency tones. In contrast, children using cochlear implants performed similarly to typically developing children for the high-frequency vowel but not for the mid- and low-frequency vowel.

Response to Letter to Editor by Norrix and Faux, 2018.

Purpose This letter aims to clarify the critical comments by Norrix and Faux (2019) regarding our article titled, "Criteria to Classify Children as Having Auditory Processing Disorders." The two main contentions highlighted by Norrix and Faux are addressed. One is about including participants who were "at risk" for auditory processing disorder (APD) rather than those diagnosed to have APD, and the other is about the use of a specific cutoff to diagnose children as having APD.

Short-Term Reliability of Different Methods of Contralateral Suppression of Transient Evoked Otoacoustic Emission in Children and Adults.

Purpose This study aimed to investigate the reliability of 3 methods to measure contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in children and adults. Method Contralateral suppression of TEOAEs was measured in 14 adults and 14 children using 3 methods with and without contralateral acoustic stimulus (CAS). Method-I having "2 s on-off" and Method-II having "10 s on-off" interleaved presentation of white noise. Method-III used "continuous presentation of white noise". Test-retest reliability was checked in adults without removing the probe (same-probe recording) and reinserting the probe (different-probe recording) and in children using a different-probe recording. Results The absolute suppression amplitude of TEOAEs was higher for "continuous noise," followed by "10 s on-off" and "2 s on-off" CAS. There was no significant effect of age across the 2 probe recordings, 3 methods of TEOAEs with and without CAS, and for the absolute suppression amplitude. Also, in adults, there was no significant difference between same-probe and different-probe recordings across the 3 methods. High internal consistency was observed on Cronbach's alpha (α > .9) for the 3 methods and 2 probe recordings. High agreement and correlation between the recordings for all 3 methods were seen using Bland-Altman plots and Pearson product-moment correlation coefficient. Conclusion The study demonstrated that highly reliable contralateral suppression of TEOAE can be measured using the 3 methods in adults and children. However, continuous presentation of CAS resulted in greater TEOAE suppression amplitude compared to interleaved presentation of CAS; hence, the former is recommended.

Criteria to Classify Children as Having Auditory Processing Disorders.

PURPOSE: The study aimed to determine a criterion to diagnose the presence of auditory processing disorder (APD) in children. METHOD: Using a standard comparison design, 280 children "not at risk" for APD and 100 children "at risk" for APD were evaluated on 4 different tests: Speech-in-Noise Test in Indian English (Yathiraj, Vanaja, & Muthuselvi, 2010), Dichotic Consonant-Vowel (Yathiraj, 1999), Duration Pattern Test (Musiek, Baran, & Pinheiro, 1990), and the Revised Auditory Memory and Sequencing Test in Indian English (Yathiraj, Vanaja, & Muthuselvi, 2010). The age of the children ranged from 6 to 10 years. RESULTS: With a cutoff criterion of 1 SD below the mean of the test scores, 8% of the children "at risk" for APD passed all the tests, whereas 28% passed with a criterion of 2 SDs below the mean scores. The tests most frequently failed by these children were Speech-in-Noise Test in Indian English and Dichotic Consonant-Vowel. CONCLUSIONS: A cutoff criterion of 2 SDs below the mean scores of typically developing children is recommended to diagnose children as having APD if they performed poorly on only one test. For children who performed poorly on more than one test, a cutoff criterion of 1 SD below the mean scores of typically developing children is recommended.

Auditory, visual and auditory-visual memory and sequencing performance in typically developing children.

OBJECTIVE: The study evaluated whether there exists a difference/relation in the way four different memory skills (memory score, sequencing score, memory span, & sequencing span) are processed through the auditory modality, visual modality and combined modalities. METHODS: Four memory skills were evaluated on 30 typically developing children aged 7 years and 8 years across three modality conditions (auditory, visual, & auditory-visual). Analogous auditory and visual stimuli were presented to evaluate the three modality conditions across the two age groups. RESULTS: The children obtained significantly higher memory scores through the auditory modality compared to the visual modality. Likewise, their memory scores were significantly higher through the auditory-visual modality condition than through the visual modality. However, no effect of modality was observed on the sequencing scores as well as for the memory and the sequencing span. A good agreement was seen between the different modality conditions that were studied (auditory, visual, & auditory-visual) for the different memory skills measures (memory scores, sequencing scores, memory span, & sequencing span). A relatively lower agreement was noted only between the auditory and visual modalities as well as between the visual and auditory-visual modality conditions for the memory scores, measured using Bland-Altman plots. CONCLUSIONS: The study highlights the efficacy of using analogous stimuli to assess the auditory, visual as well as combined modalities. The study supports the view that the performance of children on different memory skills was better through the auditory modality compared to the visual modality.

Performance-Intensity Function and Aided Improvement in Individuals With Late-Onset Auditory Neuropathy Spectrum Disorder.

OBJECTIVES: The purpose of the study was to explore the effect of intensity on speech perception in individuals with late-onset auditory neuropathy spectrum disorder (ANSD) by obtaining their performance-intensity (PI) function. Additionally, the study investigated the effect of PI function on aided speech perception. It was hypothesized that speech perception abilities of individuals with ANSD vary with intensity and may provide information regarding their aided performance. DESIGN: A factorial research design was used to obtain the PI function and aided performance. Thirty individuals with late-onset ANSD in the age range of 14 to 42 years were evaluated. All the participants had bilateral mild to moderately-severe symmetrical hearing loss and were naive hearing aid users. A PI function was obtained for each participant for phonemically-balanced words. Further, aided performance was evaluated for binaural digital hearing aids fitted using the National Acoustic Laboratories-Non-linear 1 method. RESULTS: It was found that the sensation level at which maximum word recognition scores were obtained varied across the participants. However, the majority of the participants had maximum scores below 30 dB SL. A large number of participants had a rollover PI function where the word recognition scores deteriorated with increase in presentation level. However, a few individuals demonstrated improvement in word recognition scores with increase in presentation level. Rollover index calculated from the PI function clearly demarcated those who had improved speech perception with hearing aids from those who did not. It was found that those with a rising pattern had aided speech identification scores that were significantly higher than their unaided scores. No such difference was found in those with a rollover. Further, aided benefit calculated by obtaining the difference between the aided and unaided scores was significantly higher in those with a rising PI function than those with a rollover function. CONCLUSIONS: The word recognition scores of individuals with ANSD varied with sensation level. This implies that obtaining the word recognition scores at a single presentation level may not accurately represent the speech perception abilities of those with ANSD. Further, a PI function helps differentiate those individuals with ANSD who benefit from hearing aids from those who do not.

Age related changes in auditory processes in children aged 6 to 10 years.

OBJECTIVES: The study evaluated age related changes in auditory processing (separation/auditory closure, binaural auditory integration abilities, temporal processing abilities) and higher order cognitive function (auditory memory & sequencing abilities) in children. Additionally, the study aimed to assess the effect of gender on the auditory processes/higher cognitive function as well as ear effect for the monaural tests that were administered. METHODS: The cross-sectional experimental study evaluated 280 typically developing children aged 6 to 10 years, divided into five age groups. They were evaluated on auditory processes/higher order cognitive functions reported to be frequently affected in children with auditory processing disorders (Speech-in-Noise Test in Indian-English, Dichotic consonant-vowel test, Duration pattern test, & Revised Auditory Memory and Sequencing Test in Indian-English). RESULTS: ANOVA and MANOVA revealed no significant gender effect in all four tests. However, a significant age effect was seen, with the rate at which maturation occurred, varying across the tests. CONCLUSIONS: Thus, the findings indicate that different auditory processes have different rates of development. This reflects that the areas responsible for different auditory processes/higher cognitive function do not develop at the same pace.

Comparison of Performance of Older Adults on Two Tests of Temporal Resolution.

PURPOSE: Gap-detection thresholds have been reported to vary depending on the type of stimuli used. The current study compared the performance of older adults on 2 tests of temporal resolution, one with random gaps and the other with gaps in the center of a noise signal. The study also determined which of the 2 tests was able to detect more temporal resolution deficits in older individuals. METHOD: Two tests of temporal resolution, the Gap Detection Test (GDT; Shivaprakash, 2003) and the Gaps-In-Noise test (GIN; Musiek et al., 2005), were administered to 31 older adults with near normal hearing, aged 55 to 70 years. The order in which the tests were administered was randomized. RESULTS: The gap-detection thresholds obtained using GIN were significantly higher than those obtained using GDT. The difference in thresholds was ascribed to the randomness with which gaps were interspersed within noise segments in the 2 tests. More individuals failed on GIN than GDT. The older adults with high-frequency hearing loss obtained poorer gap thresholds than those with normal hearing. CONCLUSION: The results indicated that older individuals failed GIN more often compared to GDT. This was attributed to the differences in stimuli and procedure used in the 2 tests.

Auditory, visual, and auditory-visual processing performance in typically developing children: modality independence versus dependence.

The study was carried out to determine whether cross-modal interactions occur during processing of auditory and/or visual signals that require separation/closure, integration, and duration pattern perception in typically developing children. Thirty typically developing children were evaluated on three auditory processing tests (speech-in-noise test in Indian-English, dichotic-consonant vowel test, and duration pattern test) that tapped separation/closure, integration and duration pattern perception. The children were also evaluated on the visual and auditory-visual analogues of the auditory tests. Differences in modality were found in each of the processes that were tested. The performance when the auditory and visual modalities were tested simultaneously was significantly higher than the auditory or visual modality for tests that involved separation/closure and integration. In contrast, scores on the analogous auditory-visual duration pattern test were significantly higher than the auditory test but not the visual analogous test. Further, the scores of the auditory modality were significantly poorer than the visual modality for separation/closure and duration patterning but not for integration. Findings of the study indicate that performance on higher level processing varies depending on the modality that is assessed and supports the presence of cross-modality interactions.

Validation of the Screening Test for Auditory Processing (STAP) on school-aged children.

OBJECTIVES: The present study focussed on validating the Screening Test for Auditory Processing (STAP) that contains four subsections: speech-in-noise, dichotic consonant vowel, gap detection and auditory memory. The sensitivity and specificity were ascertained by comparing the results of the screening test with that of diagnostic tests for auditory processing. METHODS: The STAP was administered on 500 school going children in the age range of 8-13 years. These consisted of 141 children who were found at-risk on the Screening Checklist for Auditory Processing (SCAP). Diagnostic APD tests (speech-in-noise, dichotic CV, gap detection and auditory memory) were administered on 152 of the children referred and/or passed on the screening procedures. RESULTS: The results from the STAP indicated that the auditory memory subsection of the STAP was the most affected followed by dichotic CV and speech-in-noise. Gap detection was the least affected among the four subsections. A high and significant correlation was noted between the subsections of the STAP and the APD diagnostic tests. The sensitivity and specificity of the STAP on comparison with the diagnostic tests was found to be 76.6% and 72%, respectively. It was found that when a combination of SCAP and STAP was used for screening, the sensitivity and specificity were higher. CONCLUSION: Based on the findings of the study, it is recommended that both SCAP and STAP be administered. Further, there was also a good test-retest reliability of the SCAP, STAP and the APD diagnostic tests.

Screening Test for Auditory Processing (STAP): a preliminary report.

BACKGROUND: The presence of auditory processing disorder in school-age children has been documented (Katz and Wilde, 1985; Chermak and Musiek, 1997; Jerger and Musiek, 2000; Muthuselvi and Yathiraj, 2009). In order to identify these children early, there is a need for a screening test that is not very time-consuming. PURPOSE: The present study aimed to evaluate the independence of four subsections of the Screening Test for Auditory Processing (STAP) developed by Yathiraj and Maggu (2012). The test was designed to address auditory separation/closure, binaural integration, temporal resolution, and auditory memory in school-age children. The study also aimed to examine the number of children who are at risk for different auditory processes. RESEARCH DESIGN: Factor analysis research design was used in the current study. STUDY SAMPLE: Four hundred school-age children consisting of 218 males and 182 females were randomly selected from 2400 children attending three schools. The children, aged 8 to 13 yr, were in grade three to eight class placements. DATA COLLECTION AND ANALYSES: The children were evaluated on the four subsections of the STAP (speech perception in noise, dichotic consonant-vowel [CV], gap detection, and auditory memory) in a quiet room within their school. The responses were analyzed using principal component analysis (PCA) and confirmatory factor analysis (CFA). In addition, the data were also analyzed to determine the number of children who were at risk for an auditory processing disorder (APD). RESULTS: Based on the PCA, three components with Eigen values greater than 1 were extracted. The orthogonal rotation of the variables using the Varimax technique revealed that component 1 consisted of binaural integration, component 2 consisted of temporal resolution, and component 3 was shared by auditory separation/closure and auditory memory. These findings were confirmed using CFA, where the predicted model displayed a good fit with or without the inclusion of the auditory memory subsection. It was determined that 16% of the children were at risk for APD on one or more of the subsections of STAP. Among these 16%, the auditory memory subsection was the most affected (73.4%), followed by binaural integration (65.6%), auditory separation/closure (59.4%), and temporal resolution (53.1%). CONCLUSION: The current study revealed that the four subsections of STAP merged to form three distinct components. Dichotic CV and gap detection formed two independent components while speech perception in noise and auditory memory merged to form a single component. This indicates a possible relationship between auditory memory and speech perception in noise as suggested by Katz (1992). Thus, STAP is able to detect three different components related to auditory processing. The study also indicates that the number of children at risk for each of the different auditory processes vary. Ongoing evaluation will shed light on the usefulness of the subsections of STAP in identifying auditory processing problems. In addition to conducting the APD screening test, it is also recommended that a hearing screening be done to rule out peripheral hearing problems when hearing screening programs are not conducted in schools.

Comparison of a screening test and screening checklist for auditory processing disorders.

OBJECTIVE: This study was carried out to determine the relationship between two screening tools to detect auditory processing disorders (APDs). The two screening tools were the screening checklist for auditory processing (SCAP) and screening test for auditory processing (STAP). METHOD: Four hundred school-going children (218 males, 182 females) studying in grades III-VIII in three schools were randomly selected for the study. These children, aged 8-13 years, were screened using the SCAP and the STAP. The SCAP was administered by teachers while the STAP was administered by an audiologist. The children were categorised as at-risk for APD by comparing their scores with the cut-off criteria recommended for SCAP and STAP. The relationship between the two screening tools was determined. RESULTS: Among the 400 children, 49 (12.3%) children were found to be at-risk for APD on the SCAP and 64 (16%) were found to be at-risk on the STAP. A Chi square test of association was carried out using the data of children who were passed or referred on each of the screening tools (SCAP and STAP). A significant association (χ(2)=2.93, df=1, p<0.001) was found between the two screening tools. This was confirmed using Spearman's rank correlation coefficient, which revealed a significant correlation (r=0.86, p<0.001) between SCAP and STAP. Using the scores of 31 children referred on both the screening tools, a relationship was derived between the SCAP and subsections of the STAP (speech-in-noise, dichotic consonant vowel (CV) combinations, gap detection and auditory memory). Pearson's product moment correlation coefficient indicated the presence of a significant correlation (r=-0.46, p<0.01) between the SCAP and the auditory memory subsection of the STAP. However, no significant correlation was seen for other three subsections. CONCLUSION: The study indicates an overall high correlation between the SCAP and the STAP. However, both the screening tools examine different aspects of auditory processing and thus, should be administered together to identify more children at-risk for APD.

The effect of a hearing aid noise reduction algorithm on the acquisition of novel speech contrasts.

Audiologists are reluctant to prescribe digital hearing aids with active digital noise reduction (DNR) to pre-verbal children due to their potential for an adverse effect on the acquisition of language. The present study investigated the relation between DNR and language acquisition by modeling pre-verbal language acquisition using adult listeners presented with a non-native speech contrast. Two groups of normal-hearing, monolingual Anglophone subjects were trained over four testing sessions to discriminate novel, difficult to discriminate, non-native Hindi speech contrasts in continuous noise, where one group listened to both speech items and noise processed with DNR, and where the other group listened to unprocessed speech in noise. Results did not reveal a significant difference in performance between groups across testing sessions. A significant learning effect was noted for both groups between the first and second testing sessions only. Overall, DNR does not appear to enhance or impair the acquisition of novel speech contrasts by adult listeners.