Informational masking was reduced using three stimulus presentation schemes that were intended to perceptually segregate the signal from the masker. The maskers were sets of sinusoids chosen randomly in frequency and intensity on each stimulus interval or, in some conditions, on every masker burst in a series of bursts within intervals. Masker components were excluded from the frequency region surrounding the 1000-Hz signal to minimize the energetic masking. Masked thresholds as great as 60–70 dB above quiet threshold were observed for some subjects in some conditions. It was shown that this informational masking could be reduced as much as 40 dB by: (1) presenting the masker to both ears and signal to one ear; (2) playing different masker samples sequentially in each interval of every trial; or (3) presenting the signal in alternate bursts of multiple, identical masker samples. For the binaural manipulation, informational masking was reduced because the masker and signal were perceived as originating from different interaural locations. In the latter two manipulations, a difference in the spectral or temporal pattern of the signal and masker provided the detection cue. These effects were interpreted as evidence of the importance of perceptual segregation of sounds in noisy listening environments where signal reception is not limited by energetic masking.

A model of auditory object formation and an experimental evaluation of the model are described. Specifically, predictions for intensity discrimination and interaural time difference discrimination for the central component of a three-component harmonic complex are evaluated empirically. The onset time of the central, target component is varied relative to the onset times of the remaining, interferer components in order to vary the degree of fusion (versus perceptual segregation) of the target and the interferers. The model, which is based on the idea of attenuation of the components in the nonattended auditory image (in the case of segregated images), predicts lower sensitivity to information at the target component for the fused versus segregated target, and equal sensitivities for completely segregated targets and targets presented in isolation. Results are presented for four subjects with component frequencies of 400, 600, and 800 Hz and with onset time differences of 0 or 250 ms. The target duration was always 100 ms and offset times were the same for all components. The subjective results were as expected, with synchronous onsets yielding one sound object, and asynchrony of the central component yielding two sound objects. Also, the empirical results on interference in the synchronous case were in qualitative agreement with the above predictions. However, significantly more interference was found than was predicted for both synchronous and asynchronous conditions. In fact, the amount of interference found contradicts the simple attenuation model of object formation.

Objective-While numerous studies have investigated the effects of single-microphone digital noise reduction algorithms for adults with hearing loss, similar studies have not been conducted with young hearing-impaired children. The goal of this study was to examine the effects of a commonlyused digital noise reduction scheme (spectral subtraction) in children with mild-moderately severe sensorineural hearing losses. It was hypothesized that the process of spectral subtraction may alter or degrade speech signals in some way. Such degradation may have little influence on the perception of speech by hearing-impaired adults who are likely to use contextual information under such circumstances. For young children who are still developing various language skills, however, signal degradation may have a more detrimental effect on the perception of speech.Design-Sixteen children (eight 5-7 year olds and eight 8-10 year olds) with mild-moderately severe hearing loss participated in this study. All participants wore binaural behind-the-ear hearing aids where noise reduction processing was performed independently in 16 bands with center frequencies spaced 500 Hz apart up to 7500 Hz. Test stimuli were nonsense syllables, words, and sentences in a background of noise. For all stimuli, data were obtained with noise reduction on and off.Results-In general, performance improved as a function of SNR for all three speech materials. The main effect for stimulus type was significant and post hoc comparisons of stimulus type indicated Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 5 In previous studies, we have found that young children will occasionally respond with a phoneme that is not part of the stimulus set.To document these instances, we elected to include an "other" category. In the analysis of both overall performance and phonetic features "other" responses were assumed to be incorrect. NIH Public AccessAuthor Manuscript Ear Hear. Author manuscript; available in PMC 2011 June 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript that speech recognition was higher for sentences than for both nonsense syllables and words, but no significant differences were observed between nonsense syllables and words. The main effect for noise reduction and the two-way interaction between noise reduction and stimulus type were not significant. Significant age group effects were observed, but the two-way interaction between NR and age group was not significant.Conclusions-Consistent with previous findings from studies with adults, results suggest that the form of noise r...

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Auditive and cognitive influences on speech perception in a complex situation were investigated in listeners with normal hearing (NH) and hearing loss (HL). The speech corpus used was the Nonsense-Syllable Response Measure [NSRM; Woods and Kalluri, (2010). International Hearing Aid Research Conference, pp. 40-41], a 12-talker corpus which combines 154 nonsense syllables with 8 different carrier phrases. Listeners heard NSRM sentences in quiet, background noise, and in background noise plus other "jammer" NSRM sentences. All stimuli were linearly amplified. A "proficiency" value, determined from the results in quiet and the quiet-condition speech intelligibility index (SII), was used with the SII in predicting results in the other conditions. Results for nine of ten NH subjects were well-predicted (within the limits of binomial variability) in the noise condition, as were eight of these subjects in the noise-plus-jammers condition. All 16 HL results were well-predicted in the noise condition, as were 9 of the HL in the noise-plus-jammers condition. Hierarchical regression partialling out the effects of age found proficiency in noise-plus-jammers significantly correlated with results of "trail-making" tests, thought to index processing speed and attention-deployment ability, and proficiency in quiet and noise was found significantly correlated with results from a backward digit-span memory test.