Auditory temporal resolution in normal-hearing preschool children revealed by word recognition in continuous and interrupted noise

Auditory modulation processing in children with mild to moderate hearing loss

BACKGROUND AND OBJECTIVE

Children with hearing loss often have difficulty understanding speech in noisy environments like classrooms, leading to educational and communication challenges. Detecting and discriminating auditory spectro-temporal fundamentals is essential for speech comprehension. So, in this study, we investigated how children with mild to moderate hearing loss (MMHL) process these auditory modulations and their relation to speech perception in noise, comparing their performance to that of children with normal hearing.

METHODS

This cross-sectional study selected 31 children with mild to moderate sensorineural hearing loss (SNHL) and 34 normally hearing (NH) children, aged 8 to 12. After obtaining consent, participants underwent tests, including the Spectral Modulation Ripple Test (SMRT), Amplitude Modulation Detection Tests (AMDTs) at 10, 50, and 200 Hz, and Speech Perception in Noise (SPiN) assessments using Word-in-Noise (WIN) and BKB-SIN tests, conducted monaurally. Results were compared between the two groups, evaluating the effects of hearing loss severity and correlations among the tests, as well as score comparisons from both ears within each group.

RESULTS

Significant differences were observed between groups (MMHL and NH) in SMRT, AMDTs, and SPiN tests (p < 0.05), with the NH group scoring better. However, no significant differences were observed between mild and moderate hearing loss (p > 0.05). There was no correlation between SMRT and AMDTs with the WIN test (p > 0.05). Notably, significant correlations were found between SMRT and BKB tests in both groups. Sporadic correlations were also identified between AMDTs at higher rates and BKB results for both groups (p < 0.05). Scores between the two ears showed no significant differences across all tests (p > 0.05).

CONCLUSION

Children with Mild to moderate SNHL have a lesser ability to use spectral and temporal modulation information, making it difficult for them to understand speech in noisy environments. Nonverbal spectral and temporal modulation tests require minimal cognitive effort and are valuable for evaluating perceptual disorders and developing auditory rehabilitation programs for these children.

Lilliput: speech perception in speech-weighted noise and in quiet in young children

OBJECTIVE

The aim of this study was to develop an open-set word recognition task in speech-weighted noise and in quiet for young children and examine age effects for open versus closed response formats.

DESIGN

Dutch monosyllabic words were presented in quiet and in stationary speech-weighted noise to 4- and 5-year-old children as well as to young adults in an open-set response format. Additionally, performance in open and closed context was assessed, as well as in a picture-pointing paradigm.

STUDY SAMPLE

More than 200 children and 50 adults with normal hearing participated in the various validation phases.

RESULTS

Average fitted speech reception thresholds (50%) yielded an age effect between 4-year and 5-year olds (and adults), both in speech-weighted noise and in quiet. The closed-set format yielded lower (better) SNRs than the open-set format, and children benefitted to the same extent as adults from phonetically similar words in speech-weighted noise. Additionally, the 4 AFC picture-pointing paradigm can be used to assess word recognition in quiet from 3 years of age.

CONCLUSIONS

The same materials reveal performance differences between 4 and 5 years of age (and adults), both in quiet and speech-weighted noise using an open-set response format. This relatively small yet significant difference in SRT for a gap of only 1 year shows a developmental change for word recognition in speech-weighted noise and in quiet in the first decade of life.The study is part of the protocol registered on ClinicalTrials.gov (ID = NCT04063748).

Development of central auditory processes in Polish children and adolescents at the age from 7 to 16 years

There are discrepancies in the literature regarding the course of central auditory processes (CAP) maturation in typically developing children and adolescents. The purpose of the study was to provide an overview of age – related improvement in CAP in Polish primary and secondary school students aged 7–16 years. 180 children/adolescents, subdivided into 9 age categories, and 20 adults (aged 18–24 years) performed the Dichotic Digit Test (DDT), Duration Pattern Test (DPT), Frequency Pattern Test (FPT), Gap Detection Test (GDT) and adaptive Speech-in-Noise (aSpN). The 12-year-olds was retested after w week. We found the age effects only for the DDT, DPT and FPT. In the right ear DDT the 7-year-olds performed more poorly than all groups ≥12. In the left ear DDT both 7- and 8-year-olds achieved less correct responses compared with the 13-, 14-, 15-year-olds and with the adults. The right ear advantage was greater in the 7-year-olds than in the 15-year-olds and adult group. At the age of 7 there was lower DPT and FPT scores than in all participants ≥13 whereas the 8-year-olds obtained less correct responses in the FPT than all age categories ≥12. Almost all groups (except for the 7-year-olds) performed better in the DPT than FPT. The test-retest reliability for all tests was satisfactory. The study demonstrated that different CAP have their own patterns of improvement with age and some of them are specific for the Polish population. The psychoacoustic battery may be useful in screening for CAP disorders in Poland.

An examination of electrophysiological release from masking in young and older adults

The effect of age on release from masking (RFM) was examined using cortical auditory evoked potentials (CAEPs). Two speech-in-noise paradigms [i.e., fixed speech with varying signal-to-noise ratios (SNRs) and fixed noise with varying speech levels], similar to those used in behavioral measures of RFM, were employed with competing continuous and interrupted noises. Young and older normal-hearing adults participated (N = 36). Cortical responses were evoked in the fixed speech paradigm at SNRs of -10, 0, and 10 dB. In the fixed noise paradigm, the CAEP SNR threshold was determined in both noises as the lowest SNR that yielded a measurable response. RFM was demonstrated in the fixed speech paradigm with a significant amount of missing responses, longer P1 and N1 latencies, and smaller N1 response amplitudes in continuous noise at the poorest -10 dB SNR. In the fixed noise paradigm, RFM was demonstrated with significantly lower CAEP SNR thresholds in interrupted noise. Older participants demonstrated significantly longer P2 latencies and reduced P1 and N1 amplitudes. There was no evidence of a group difference in RFM in either paradigm.

Masking Release for Speech in Modulated Maskers: Electrophysiological and Behavioral Measures

OBJECTIVES

The purpose of this study was to obtain an electrophysiological analog of masking release using speech-evoked cortical potentials in steady and modulated maskers and to relate this masking release to behavioral measures for the same stimuli. The hypothesis was that the evoked potentials can be tracked to a lower stimulus level in a modulated masker than in a steady masker and that the magnitude of this electrophysiological masking release is of the same order as that of the behavioral masking release for the same stimuli.

DESIGN

Cortical potentials evoked by an 80-ms /ba/ stimulus were measured in two steady maskers (30 and 65 dB SPL), and in a masker that modulated between these two levels at a rate of 25 Hz. In each masker, a level series was undertaken to determine electrophysiological threshold. Behavioral detection thresholds were determined in the same maskers using an adaptive tracking procedure. Masking release was defined as the difference between signal thresholds measured in the steady 65-dB SPL masker and the modulated masker. A total of 23 normal-hearing adults participated.

RESULTS

Electrophysiological thresholds were uniformly elevated relative to behavioral thresholds by about 6.5 dB. However, the magnitude of masking release was about 13.5 dB for both measurement domains.

CONCLUSIONS

Electrophysiological measures of masking release using speech-evoked cortical auditory evoked potentials correspond closely to behavioral estimates for the same stimuli. This suggests that objective measures based on electrophysiological techniques can be used to reliably gauge aspects of temporal processing ability.

Pediatric Hearing Loss and Speech Recognition in Quiet and in Different Types of Background Noise

Purpose Speech recognition deteriorates with hearing loss, particularly in fluctuating background noise. This study examined how hearing loss affects speech recognition in different types of noise to clarify how characteristics of the noise interact with the benefits listeners receive when listening in fluctuating compared to steady-state noise. Method Speech reception thresholds were measured for a closed set of spondee words in children (ages 5-17 years) in quiet, speech-spectrum noise, 2-talker babble, and instrumental music. Twenty children with normal hearing and 43 children with hearing loss participated; children with hearing loss were subdivided into groups with cochlear implant (18 children) and hearing aid (25 children) groups. A cohort of adults with normal hearing was included for comparison. Results Hearing loss had a large effect on speech recognition for each condition, but the effect of hearing loss was largest in 2-talker babble and smallest in speech-spectrum noise. Children with normal hearing had better speech recognition in 2-talker babble than in speech-spectrum noise, whereas children with hearing loss had worse recognition in 2-talker babble than in speech-spectrum noise. Almost all subjects had better speech recognition in instrumental music compared to speech-spectrum noise, but with less of a difference observed for children with hearing loss. Conclusions Speech recognition is more sensitive to the effects of hearing loss when measured in fluctuating compared to steady-state noise. Speech recognition measured in fluctuating noise depends on an interaction of hearing loss with characteristics of the background noise; specifically, children with hearing loss were able to derive a substantial benefit for listening in fluctuating noise when measured in instrumental music compared to 2-talker babble.

Forward and Backward Masking of Consonants in School-Age Children and Adults

PURPOSE

This experiment sought to determine whether children's increased susceptibility to nonsimultaneous masking, particularly backward masking, is evident for speech stimuli.

METHOD

Five- to 9-year-olds and adults with normal hearing heard nonsense consonant-vowel-consonant targets. In Experiments 1 and 2, those targets were presented between two 250-ms segments of 70-dB-SPL speech-shaped noise, at either -30 dB signal-to-noise ratio (Experiment 1) or at the listener's word recognition threshold (Experiment 2). In Experiment 3, the target was presented in steady speech-shaped noise at listener threshold. For all experiments, percent correct was estimated for initial and final consonants.

RESULTS

In the nonsimultaneous noise conditions, child-adult differences were larger for the final consonant than the initial consonant whether listeners were tested at -30 dB signal-to-noise ratio (Experiment 1) or at their individual word recognition threshold (Experiment 2). Children were not particularly susceptible to backward masking relative to adults when tested in a steady masker (Experiment 3).

CONCLUSIONS

Child-adult differences were greater for backward than forward masking for speech in a nonsimultaneous noise masker, as observed in previous psychophysical studies using tonal stimuli. Children's greater susceptibility to nonsimultaneous masking, and backward masking in particular, could play a role in their limited ability to benefit from masker envelope modulation when recognizing masked speech.

Speech Perception in Complex Acoustic Environments: Developmental Effects

PURPOSE

The ability to hear and understand speech in complex acoustic environments follows a prolonged time course of development. The purpose of this article is to provide a general overview of the literature describing age effects in susceptibility to auditory masking in the context of speech recognition, including a summary of findings related to the maturation of processes thought to facilitate segregation of target from competing speech.

METHOD

Data from published and ongoing studies are discussed, with a focus on synthesizing results from studies that address age-related changes in the ability to perceive speech in the presence of a small number of competing talkers.

CONCLUSIONS

This review provides a summary of the current state of knowledge that is valuable for researchers and clinicians. It highlights the importance of considering listener factors, such as age and hearing status, as well as stimulus factors, such as masker type, when interpreting masked speech recognition data.

PRESENTATION VIDEO

http://cred.pubs.asha.org/article.aspx?articleid=2601620.

Evidence of a speech evoked electrophysiological release from masking in noise

In this study, a release from masking (RFM) was sought with cortical auditory evoked potentials (CAEPs) elicited by speech (/da/) in competing continuous and interrupted noises. Two paradigms (i.e., fixed speech with varying signal-to-noise ratios and fixed noise with varying speech levels) were employed. Shorter latencies and larger amplitudes were observed in interrupted versus continuous noise at equivalent signal-to-noise ratios. With fixed speech presentation, P1-N1-P2 latencies were prolonged and peak N1 and P2 amplitudes decreased and more so with continuous noise. CAEP thresholds were lower in interrupted noise. This is the first demonstration of RFM with CAEPs to speech.

Mandarin-Speaking Children's Speech Recognition: Developmental Changes in the Influences of Semantic Context and F0 Contours

The goal of this developmental speech perception study was to assess whether and how age group modulated the influences of high-level semantic context and low-level fundamental frequency (F₀) contours on the recognition of Mandarin speech by elementary and middle-school-aged children in quiet and interference backgrounds. The results revealed different patterns for semantic and F₀ information. One the one hand, age group modulated significantly the use of F₀ contours, indicating that elementary school children relied more on natural F₀ contours than middle school children during Mandarin speech recognition. On the other hand, there was no significant modulation effect of age group on semantic context, indicating that children of both age groups used semantic context to assist speech recognition to a similar extent. Furthermore, the significant modulation effect of age group on the interaction between F₀ contours and semantic context revealed that younger children could not make better use of semantic context in recognizing speech with flat F₀ contours compared with natural F₀ contours, while older children could benefit from semantic context even when natural F₀ contours were altered, thus confirming the important role of F₀ contours in Mandarin speech recognition by elementary school children. The developmental changes in the effects of high-level semantic and low-level F₀ information on speech recognition might reflect the differences in auditory and cognitive resources associated with processing of the two types of information in speech perception.

Speech recognition in one- and two-talker maskers in school-age children and adults: Development of perceptual masking and glimpsing

Children perform more poorly than adults on a wide range of masked speech perception paradigms, but this effect is particularly pronounced when the masker itself is also composed of speech. The present study evaluated two factors that might contribute to this effect: the ability to perceptually isolate the target from masker speech, and the ability to recognize target speech based on sparse cues (glimpsing). Speech reception thresholds (SRTs) were estimated for closed-set, disyllabic word recognition in children (5-16 years) and adults in a one- or two-talker masker. Speech maskers were 60 dB sound pressure level (SPL), and they were either presented alone or in combination with a 50-dB-SPL speech-shaped noise masker. There was an age effect overall, but performance was adult-like at a younger age for the one-talker than the two-talker masker. Noise tended to elevate SRTs, particularly for older children and adults, and when summed with the one-talker masker. Removing time-frequency epochs associated with a poor target-to-masker ratio markedly improved SRTs, with larger effects for younger listeners; the age effect was not eliminated, however. Results were interpreted as indicating that development of speech-in-speech recognition is likely impacted by development of both perceptual masking and the ability recognize speech based on sparse cues.

Linguistic Factors Influencing Speech Audiometric Assessment

In speech audiometric testing, hearing performance is typically measured by calculating the number of correct repetitions of a speech stimulus. We investigate to what extent the repetition accuracy of Dutch speech stimuli presented against a background noise is influenced by nonauditory processes. We show that variation in verbal repetition accuracy is partially explained by morpholexical and syntactic features of the target language. Verbs, prepositions, conjunctions, determiners, and pronouns yield significantly lower correct repetitions than nouns, adjectives, or adverbs. The reduced repetition performance for verbs and function words is probably best explained by the similarities in the perceptual nature of verbal morphology and function words in Dutch. For sentences, an overall negative effect of syntactic complexity on speech repetition accuracy was found. The lowest number of correct repetitions was obtained with passive sentences, reflecting the cognitive cost of processing a noncanonical sentence structure. Taken together, these findings may have important implications for the audiological practice. In combination with hearing loss, linguistic complexity may increase the cognitive demands to process sentences in noise, leading to suboptimal functional hearing in day-to-day listening situations. Using test sentences with varying degrees of syntactic complexity may therefore provide useful information to measure functional hearing benefits.

Effect of response context and masker type on word recognition in school-age children and adults

In adults, masked speech recognition improves with the provision of a closed set of response alternatives. The present study evaluated whether school-age children (5-13 years) benefit to the same extent as adults from a forced-choice context, and whether this effect depends on masker type. Experiment 1 compared masked speech reception thresholds for disyllabic words in either an open-set or a four-alternative forced-choice (4AFC) task. Maskers were speech-shaped noise or two-talker speech. Experiment 2 compared masked speech reception thresholds for monosyllabic words in two 4AFC tasks, one in which the target and foils were phonetically similar and one in which they were dissimilar. Maskers were speech-shaped noise, amplitude-modulated noise, or two-talker speech. For both experiments, it was predicted that children would not benefit from the information provided by the 4AFC context to the same degree as adults, particularly when the masker was complex (two-talker) or when audible speech cues were temporally sparse (modulated-noise). Results indicate that young children do benefit from a 4AFC context to the same extent as adults in speech-shaped noise and amplitude-modulated noise, but the benefit of context increases with listener age for the two-talker speech masker.

Factors affecting the development of speech recognition in steady and modulated noise

This study used a checkerboard-masking paradigm to investigate the development of the speech reception threshold (SRT) for monosyllabic words in synchronously and asynchronously modulated noise. In asynchronous modulation, masker frequencies below 1300 Hz were gated off when frequencies above 1300 Hz were gated on, and vice versa. The goals of the study were to examine development of the ability to use asynchronous spectro-temporal cues for speech recognition and to assess factors related to speech frequency region and audible speech bandwidth. A speech-shaped noise masker was steady or was modulated synchronously or asynchronously across frequency. Target words were presented to 5-7 year old children or to adults. Overall, children showed higher SRTs and smaller masking release than adults. Consideration of the present results along with previous findings supports the idea that children can have particularly poor masked SRTs when the speech and masker spectra differ substantially, and that this may arise due to children requiring a wider speech bandwidth than adults for speech recognition. The results were also consistent with the idea that children are relatively poor in integrating speech cues when the frequency regions with the best signal-to-noise ratios vary across frequency as a function of time.

Children's perception of conversational and clear American-English vowels in noise

PURPOSE

Much of a child's day is spent listening to speech in the presence of background noise. Although accurate vowel perception is important for listeners' accurate speech perception and comprehension, little is known about children's vowel perception in noise. Clear speech is a speech style frequently used by talkers in the presence of noise. This study investigated children's identification of vowels in nonsense words in noise and examined whether adults' use of clear speech would result in the children's more accurate vowel identification.

METHOD

Two female American-English (AE) speaking adults were recorded producing the nonsense word /gəbVpə/ with AE vowels /ɛ-æ-ɑ-ʌ/ in phrases in conversational and clear speech. These utterances were presented to 15 AE-speaking children (ages 5.0-8.5 years) at a signal-to-noise ratio of -6 dB. The children repeated the utterances.

RESULTS

Clear-speech vowels were repeated significantly more accurately (87%) than conversational-speech vowels (59%), suggesting that clear speech aids children's vowel identification. Children repeated one talker's vowels more accurately than the other's, and front vowels more accurately than central and back vowels.

CONCLUSION

The findings support the use of clear speech for enhancing adult-to-child communication in AE in noisy environments.

Development of spatial release from masking in mandarin-speaking children with normal hearing

PURPOSE

This study investigated the development of spatial release from masking in children using closed-set Mandarin disyllabic words and monosyllabic words carrying lexical tones as test stimuli and speech spectrum-weighted noise as a masker.

METHOD

Twenty-six children ages 4-9 years and 12 adults, all with normal hearing, participated in speech recognition tests under 2 conditions: (a) speech and noise spatially mixed and presented from the front (NF), and (b) speech presented from the front with noise spatially separated and presented from the side (NS) with different signal-to-noise ratios (SNRs). Performance-SNR psychometric functions were obtained that generated the SNR for a 50% correct score (SNR-50%) as the outcome measure.

RESULTS

In the child participants, SNR-50% improved with age in NS but not NF. The difference in SNR-50% between NS and NF-the spatial release from masking (SRM)-increased with age with an average improvement of 0.1-0.15 dB per month.

CONCLUSIONS

SRM has a long developmental time, at least up to 9 years of age, which is significantly longer than some previous developmental studies have suggested. The child participants had not yet reached the adult SRM performance level. SRM is a potential clinical measure to reflect the maturation of spatial auditory processing.

Development of speech glimpsing in synchronously and asynchronously modulated noise

This study investigated development of the ability to integrate glimpses of speech in modulated noise. Noise was modulated synchronously across frequency or asynchronously such that when noise below 1300 Hz was "off," noise above 1300 Hz was "on," and vice versa. Asynchronous masking was used to examine the ability of listeners to integrate speech glimpses separated across time and frequency. The study used the Word Intelligibility by Picture Identification (WIPI) test and included adults, older children (age 8-10 yr) and younger children (5-7 yr). Results showed poorer masking release for the children than the adults for synchronous modulation but not for asynchronous modulation. It is possible that children can integrate cues relatively well when all intervals provide at least partial speech information (asynchronous modulation) but less well when some intervals provide little or no information (synchronous modulation). Control conditions indicated that children appeared to derive less benefit than adults from speech cues below 1300 Hz. This frequency effect was supported by supplementary conditions where the noise was unmodulated and the speech was low- or high-pass filtered. Possible sources of the developmental frequency effect include differences in frequency weighting, effective speech bandwidth, and the signal-to-noise ratio in the unmodulated noise condition.

Children's identification of consonants in a speech-shaped noise or a two-talker masker

PURPOSE

To evaluate child-adult differences for consonant identification in a noise or a 2-talker masker. Error patterns were compared across age and masker type to test the hypothesis that errors with the noise masker reflect limitations in the peripheral encoding of speech, whereas errors with the 2-talker masker reflect target-masker confusions within the central auditory system.

METHOD

A repeated-measures design compared the performance of children (5-13 years) and adults in continuous speech-shaped noise or a 2-talker masker. Consonants were identified from a closed set of 12 using a picture-pointing response.

RESULTS

In speech-shaped noise, children under age 10 years performed more poorly than adults, but performance was adultlike for 11- to 13-year-olds. In the 2-talker masker, significant child-adult differences were observed in even the oldest group of children. Systematic clusters of consonant errors were observed for children in the noise masker and for adults in both maskers, but not for children in the 2-talker masker.

CONCLUSIONS

These results suggest a more prolonged time course of development for consonant identification in a 2-talker masker than in a noise masker. Differences in error patterns between the maskers support the hypothesis that errors with the 2-talker masker reflect failures of sound segregation.

Infants' detection and discrimination of sounds in modulated maskers

Adults and 7-month-old infants were compared in detection and discrimination of sounds in modulated maskers. In two experiments, the level of a target sound was varied to equate listeners' performance in unmodulated noise, and performance was assessed at that level in a noise modulated with the envelope of single-talker speech. While adults' vowel discrimination and tone detection were better in the modulated than in the unmodulated masker, infants' vowel discrimination was poorer in the modulated than in the unmodulated masker. Infants' tone detection was the same in the two maskers. In two additional experiments, each age group was tested at one level with order of testing in modulated and unmodulated maskers counterbalanced across subjects. Both infants and adults discriminated between vowels better in single-talker modulated and sinusoidally amplitude modulated (SAM) maskers than in an unmodulated masker, but infants' modulated-unmodulated difference was smaller than than that of adults. Increasing the modulation depth of the SAM masker did not affect the size of infants' modulated-unmodulated difference. However, infants' asymptotic performance in a modulated masker limits the extent to which their performance could improve. Infants can make use of information in masker dips, but masker modulation may also interfere with their ability to process the target.

Effects of reverberation on speech recognition in stationary and modulated noise by school-aged children and young adults

OBJECTIVES

The purpose of this study was to determine how combinations of reverberation and noise, typical of environments in many elementary school classrooms, affect normal-hearing school-aged children's speech recognition in stationary and amplitude-modulated noise, and to compare their performance with that of normal-hearing young adults. In addition, the magnitude of release from masking in the modulated noise relative to that in stationary noise was compared across age groups in nonreverberant and reverberant listening conditions. Last, for all noise and reverberation combinations the degree of change in predicted performance at 70% correct was obtained for all age groups using a best-fit cubic polynomial.

DESIGN

Bamford-Kowal-Bench sentences and noise were convolved with binaural room impulse responses representing nonreverberant and reverberant environments to create test materials representative of both audiology clinics and school classroom environments. Speech recognition of 48 school-aged children and 12 adults was measured in speech-shaped and amplitude-modulated speech-shaped noise, in the following three virtual listening environments: nonreverberant, reverberant at 2 m, and reverberant at 6 m.

RESULTS

Speech recognition decreased in the reverberant conditions and with decreasing age. Release from masking in modulated noise relative to stationary noise decreased with age and was reduced by reverberation. In the nonreverberant condition, participants showed similar amounts of masking release across ages. The slopes of performance-intensity functions increased with age, with the exception of the nonreverberant modulated masker condition. The slopes were steeper in the stationary masker conditions, where they also decreased with reverberation and distance. In the presence of a modulated masker, the slopes did not differ between the two reverberant conditions.

CONCLUSIONS

The results of this study reveal systematic developmental changes in speech recognition in noisy and reverberant environments for elementary-school-aged children. The overall pattern suggests that younger children require better acoustic conditions to achieve sentence recognition equivalent to their older peers and adults. In addition, this is the first study to report a reduction of masking release in children as a result of reverberation. Results support the importance of minimizing noise and reverberation in classrooms, and highlight the need to incorporate noise and reverberation into audiological speech-recognition testing to improve predictions of performance in the real world.

The monaural temporal window based on masking period pattern data in school-aged children and adults

Several lines of evidence indicate that auditory temporal resolution improves over childhood, whereas other data implicate the development of processing efficiency. The present study used the masking period pattern paradigm to examine the maturation of temporal processing in normal-hearing children (4.8 to 10.7 yrs) compared to adults. Thresholds for a brief tone were measured at 6 temporal positions relative to the period of a 5-Hz quasi-square-wave masker envelope, with a 20-dB modulation depth, as well as in 2 steady maskers. The signal was a pure tone at either 1000 or 6500 Hz, and the masker was a band of noise, either spectrally wide or narrow (21.3 and 1.4 equivalent rectangular bandwidths, respectively). Masker modulation improved thresholds more for wide than narrow bandwidths, and adults tended to receive more benefit from modulation than young children. Fits to data for the wide maskers indicated a change in window symmetry with development, reflecting relatively greater backward masking for the youngest listeners. Data for children >6.5 yrs of age appeared more adult-like for the 6500- than the 1000-Hz signal. Differences in temporal window asymmetry with listener age cannot be entirely explained as a consequence of a higher criterion for detection in children, a form of inefficiency.

Sensitivity of school-aged children to pitch-related cues

Two experiments investigated the ability of 17 school-aged children to process purely temporal and spectro-temporal cues that signal changes in pitch. Percentage correct was measured for the discrimination of sinusoidal amplitude modulation rate (AMR) of broadband noise in experiment 1 and for the discrimination of fundamental frequency (F0) of broadband sine-phase harmonic complexes in experiment 2. The reference AMR was 100 Hz as was the reference F0. A child-friendly interface helped listeners to remain attentive to the task. Data were fitted using a maximum-likelihood technique that extracted threshold, slope, and lapse rate. All thresholds were subsequently standardized to a common d' value equal to 0.77. There were relatively large individual differences across listeners: eight had relatively adult-like thresholds in both tasks and nine had higher thresholds. However, these individual differences did not vary systematically with age, over the span of 6-16 yr. Thresholds were correlated across the two tasks and were about nine times finer for F0 discrimination than for AMR discrimination as has been previously observed in adults.

Normative data for the Words-in-Noise Test for 6- to 12-year-old children

PURPOSE

To establish normative data for children on the Words-in-Noise Test (WIN; R. H. Wilson, 2003; R. H. Wilson & R. McArdle, 2007).

METHOD

Forty-two children in each of 7 age groups, ranging in age from 6 to 12 years (n=294), and 24 young adults (age range: 18-27 years) with normal hearing for pure tones participated. All listeners were screened at 15 dB HL (American National Standards Institute, 2004) with the octave interval between 500 and 4000 Hz. Randomizations of WIN Lists 1, 2, and 1 or WIN Lists 2, 1, and 2 were presented with the noise fixed at 70 dB SPL, followed by presentation at 90 dB SPL of the 70 Northwestern University Auditory Test No. 6 (T. W. Tillman & R. Carhart, 1966) words used in the WIN. Finally, the Peabody Picture Vocabulary Test-Revised (L. M. Dunn & L. M. Dunn, 1981) was administered. Testing was conducted in a quiet room.

RESULTS

There were 3 main findings: (a) The biggest change in recognition performance occurred between the ages of 6 and 7 years; (b) from 9 to 12 years, recognition performance was stable; and (c) performance by young adults (18-27 years) was slightly better (1-2 dB) than performance by the older children.

CONCLUSION

The WIN can be used with children as young as 6 years of age; however, age-specific ranges of normal recognition performance must be used.

Children's recognition of American English consonants in noise

In contrast to the availability of consonant confusion studies with adults, to date, no investigators have compared children's consonant confusion patterns in noise to those of adults in a single study. To examine whether children's error patterns are similar to those of adults, three groups of children (24 each in 4-5, 6-7, and 8-9 yrs. old) and 24 adult native speakers of American English (AE) performed a recognition task for 15 AE consonants in /ɑ/-consonant-/ɑ/ nonsense syllables presented in a background of speech-shaped noise. Three signal-to-noise ratios (SNR: 0, +5, and +10 dB) were used. Although the performance improved as a function of age, the overall consonant recognition accuracy as a function of SNR improved at a similar rate for all groups. Detailed analyses using phonetic features (manner, place, and voicing) revealed that stop consonants were the most problematic for all groups. In addition, for the younger children, front consonants presented in the 0 dB SNR condition were more error prone than others. These results suggested that children's use of phonetic cues do not develop at the same rate for all phonetic features.

Ear and contralateral masker effects on auditory temporal gap detection thresholds

A temporal processing advantage is thought to underlie the left hemisphere dominance for language. One measure of a temporal processing advantage is temporal acuity or resolution. A standard paradigm for measuring auditory temporal resolution is gap detection in its "within-channel" and "between-channel" forms. Previous experiments investigating a right ear advantage for within-channel gap detection have yielded conflicting results, and between-channel gap detection has not previously been studied for ear differences. In the present study, the two types of gap detection task were employed, under each of three contralateral masking conditions (no noise, continuous noise and interrupted noise). An adaptive tracking procedure was used to measure the minimal detectable gap at each ear (and therefore, the temporal acuity of the contralateral hemisphere). A significant effect of masking noise was observed in both of the gap detection tasks. Within-channel gap threshold durations were longer in the interrupted noise condition for both ears. Between-channel gap threshold durations were shorter in the interrupted noise condition at the left ear, with a trend in the same direction at the right ear. The study found no significant difference between the ears in thresholds in either gap detection task in any of the masking conditions. This suggests that if the left cerebral hemisphere has a temporal processing advantage, then it is not in the form of acuity for temporal gap detection.