Loud Music Exposure and Cochlear Synaptopathy in Young Adults: Isolated Auditory Brainstem Response Effects but No Perceptual Consequences.

The purpose of this study was to test the hypothesis that listeners with frequent exposure to loud music exhibit deficits in suprathreshold auditory performance consistent with cochlear synaptopathy. Young adults with normal audiograms were recruited who either did ( n = 31) or did not ( n = 30) have a history of frequent attendance at loud music venues where the typical sound levels could be expected to result in temporary threshold shifts. A test battery was administered that comprised three sets of procedures: (a) electrophysiological tests including distortion product otoacoustic emissions, auditory brainstem responses, envelope following responses, and the acoustic change complex evoked by an interaural phase inversion; (b) psychoacoustic tests including temporal modulation detection, spectral modulation detection, and sensitivity to interaural phase; and (c) speech tests including filtered phoneme recognition and speech-in-noise recognition.

Gap Detection in School-Age Children and Adults: Center Frequency and Ramp Duration.

Purpose: The age at which gap detection becomes adultlike differs, depending on the stimulus characteristics. The present study evaluated whether the developmental trajectory differs as a function of stimulus frequency region or duration of the onset and offset ramps bounding the gap.

Method: Thresholds were obtained for wideband noise (500-4500 Hz) with 4- or 40-ms raised-cosine ramps and for a 25-Hz-wide low-fluctuation narrowband noise centered on either 500 or 5000 Hz with 40-ms ramps.

Effects of Self-Generated Noise on Estimates of Detection Threshold in Quiet for School-Age Children and Adults.

Objectives: Detection thresholds in quiet become adult-like earlier in childhood for high than low frequencies. When adults listen for sounds near threshold, they tend to engage in behaviors that reduce physiologic noise (e.g.

Cochlear hearing loss and the detection of sinusoidal versus random amplitude modulation.

This study assessed the effect of cochlear hearing loss on detection of random and sinusoidal amplitude modulation. Listeners with hearing loss and normal-hearing listeners (eight per group) generated temporal modulation transfer functions (TMTFs) for envelope fluctuations carried by a 2000-Hz pure tone. TMTFs for the two groups were similar at low modulation rates but diverged at higher rates presumably because of differences in frequency selectivity.

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.

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.

The Effects of Sensorineural Hearing Impairment on Asynchronous Glimpsing of Speech.

In a previous study with normal-hearing listeners, we evaluated consonant identification masked by two or more spectrally contiguous bands of noise, with asynchronous square-wave modulation applied to neighboring bands. Speech recognition thresholds were 5.1-8.

The effect of noise fluctuation and spectral bandwidth on gap detection.

Experiment 1 investigated gap detection for random and low-fluctuation noise (LFN) markers as a function of bandwidth (25-1600 Hz), level [40 or 75 dB sound pressure level (SPL)], and center frequency (500-4000 Hz). Gap thresholds for random noise improved as bandwidth increased from 25 to 1600 Hz, but there were only minor effects related to center frequency and level. For narrow bandwidths, thresholds were lower for LFN than random markers; this difference extended to higher bandwidths at the higher center frequencies and was particularly large at high stimulus level.

Temporal Processing Deficits in Middle Age.

Purpose: The purpose of this brief report is to provide a synopsis of recent work, primarily from the authors' laboratory, that points to the emergence of temporal processing deficits relatively early in the aging process.

Method: The approach taken was to provide a descriptive summary of selected published and current experiments focusing on the processing of temporal envelopes and fine structure.

Conclusion: Deficits in both temporal envelope and temporal fine structure processing are evident during middle age even while audiometric hearing sensitivity remains normal.

Effect of stimulus bandwidth and duration on monaural envelope correlation perception.

Monaural envelope correlation perception is the ability to discriminate between stimuli composed of two or more bands of noise based on envelope correlation. Sensitivity decreases as stimulus bandwidth is reduced below 100 Hz. The present study manipulated stimulus bandwidth (25-100 Hz) and duration (25-800 ms) to evaluate whether performance of highly trained listeners is limited by the number of inherent modulation periods in each presentation.

Masked sentence recognition assessed at ascending target-to-masker ratios: modest effects of repeating stimuli.

Objectives: Masked sentence recognition is typically evaluated by presenting a novel stimulus on each trial. As a consequence, experiments calling for replicate estimates in multiple conditions require large corpora of stimuli. The present study evaluated the consequences of repeating sentence-plus-masker pairs at ascending target-to-masker ratios (TMRs).

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.

Gap detection in school-age children and adults: effects of inherent envelope modulation and the availability of cues across frequency.

Purpose: The present study evaluated the effects of inherent envelope modulation and the availability of cues across frequency on behavioral gap detection with noise-band stimuli in school-age children.

Method: Listeners were 34 normal-hearing children (ages 5.2-15.

Effects of linguistic experience on the ability to benefit from temporal and spectral masker modulation.

Masked speech perception can often be improved by modulating the masker temporally and/or spectrally. These effects tend to be larger in normal-hearing listeners than hearing-impaired listeners, and effects of temporal modulation are larger in adults than young children [Hall et al. (2012).

Across-frequency envelope correlation discrimination and masked signal detection.

This study compared the dependence of comodulation masking release (CMR) and monaural envelope correlation perception (MECP) on the degree of envelope correlation for the same narrowband noise stimuli. Envelope correlation across noise bands was systematically varied by mixing independent bands with a base set of comodulated bands. The magnitude of CMR fell monotonically with reductions in envelope correlation, and CMR varied over a range of envelope correlations that were not discriminable from each other in the MECP paradigm.

Wideband monaural envelope correlation perception.

This study investigated monaural envelope correlation perception (Richards 1987) for noise bandwidths ranging from 25 to 1,600 Hz. The high-frequency side of the low band was fixed at 3,000 Hz and the low-frequency side of the high band was fixed at 3,500 Hz. When comodulated, the magnitude spectra of the pair of noise bands were either identical or reflected around the midpoint.

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.

Monaural envelope correlation perception for bands narrower or wider than a critical band.

Monaural envelope correlation perception concerns the ability of listeners to discriminate stimuli based on the degree of correlation between the temporal envelopes of two or more frequency-separated bands of noise [Richards, J. Acoust. Soc.

Effects of masker envelope irregularities on tone detection in narrowband and broadband noise maskers.

Introducing coherent masker envelope modulation to frequency regions neighboring the signal frequency can reduce detection thresholds for a pure-tone signal. Verhey and Ernst (2009) reported that irregular masker modulation conferred greater benefit than regular modulation when the masker was broadband, but that there was no difference when the masker was narrowband. The present study evaluated two possible explanations for this result: one based on modulation adaptation and the other based on the introduction of relatively long-duration modulation minima in the irregular masker modulation condition.

Factors affecting the processing of intensity in school-aged children.

Purpose: Thresholds of school-aged children are elevated relative to those of adults for intensity discrimination and amplitude modulation (AM) detection. It is unclear how these findings are related or what role stimulus gating and dynamic envelope cues play in these results. Two experiments assessed the development of sensitivity to intensity increments in different stimulus contexts.

Asynchronous glimpsing of speech: spread of masking and task set-size.

Howard-Jones and Rosen [(1993). J. Acoust.

Frequency discrimination under conditions of comodulation masking release (L).

Masked detection thresholds can often be improved by introducing coherent masker amplitude modulation across frequency, a phenomenon referred to as comodulation masking release (CMR). While CMR can be large for detection, it is smaller for supra-threshold tasks, such as intensity discrimination. In this experiment, frequency discrimination for a 1000-Hz tone near threshold was found to be poorer in an amplitude-modulated than a steady bandpass noise.

Binaural beat salience.

Previous studies of binaural beats have noted individual variability and response lability, but little attention has been paid to the salience of the binaural beat percept. The purpose of this study was to gauge the strength of the binaural beat percept by matching its salience to that of sinusoidal amplitude modulation (SAM), and to then compare rate discrimination for the two types of fluctuation. Rate discrimination was measured for standard rates of 4, 8, 16, and 32 Hz - all in the 500-Hz carrier region.

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.

Exploring the additivity of binaural and monaural masking release.

Experiment 1 examined comodulation masking release (CMR) for a 700-Hz tonal signal under conditions of N(o)S(o) (noise and signal interaurally in phase) and N(o)S(π) (noise in phase, signal out of phase) stimulation. The baseline stimulus for CMR was either a single 24-Hz wide narrowband noise centered on the signal frequency [on-signal band (OSB)] or the OSB plus, a set of flanking noise bands having random envelopes. Masking noise was either gated or continuous.