Effects of Simulated Reverberation on the Speech-perception Abilities of Listeners with Normal Hearing PDF Download

Author: Brian Matthew Kreisman
Publisher:
ISBN:
Category :
Languages : en
Pages : 312

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Author: Chhayakanta Patro
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In suboptimal listening environments when noise hinders the continuity of the speech, the normal auditory-cognitive system perceptually integrates available speech information and & ldquo;fills in & rdquo; missing information with help from higher level feedback mechanisms. However, individuals with cochlear implants (CIs) find it difficult and effortful to understand interrupted speech compared to their normal hearing (NH) counterparts. Little is known about CI listeners & rsquo; ability to restore missing speech when they are exposed to challenging listening environments. In this dissertation, three experimental paradigms were used to evaluate listeners & rsquo; ability to utilize their acquired linguistic skills in normal hearing individuals using simulated cochlear implant processing and in individuals with cochlear implants. In the first experiment, listeners & rsquo; abilities to use semantic context when speech was intact or interrupted was evaluated under various spectral resolution conditions. The results suggested that higher level processing facilitates speech perception up to a point but it fails to facilitate speech understanding when speech signals are significantly degraded. In the second experiment, high level processing was investigated using the phonemic restoration effect where sentences were interrupted with and without filler noise at different interruption rates. Both groups failed to show top-down restoration, except the CI users showed some amount of higher level processing at the lowest interruption rate. In the third experiment, a gated word recognition task was used and listeners with CIs required comparatively more acoustic-phonetic information to recognize a word than the NH listeners. In the final experiment, when speech was presented in noise, both groups relied significantly on contextual cues to perceive the speech. Overall, the results from successive experiments indicated CI users rely heavily on contextual cues when they are available. However, when they listen to speech with severe degradations, they may not benefit from semantic context as the incoming speech does not provide enough information to trigger top-down processes. If the signal fidelity (spectral resolution) is improved, their benefit from higher level linguistic feedback processes can be maximized.

Author: Suzanne Patricia Carr
Publisher:
ISBN:
Category :
Languages : en
Pages : 212

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Abstract: Understanding speech in noisy and reverberant environments is a task that normal listeners can perform quite well and with which the hearing impaired have great difficulty. Comparing the performance of these two groups of listeners while varying perceptual cues gives insight into the segregation abilities of both normal and impaired auditory systems. The ability of normal and hearing-impaired listeners to use the segregation cues of pitch and spatial separation was measured in a speech intelligibility task, and the detrimental effects of reverberation on those cues was also measured. The target was always simulated as straight ahead (at 0 degrees azimuth). Three spatial configurations of the two masking talkers were simulated: (1) both maskers colocated with the target at 0 degrees; (2) maskers symmetrically placed at +60 and -60 degrees; and (3) both maskers located at +60 degrees azimuth. Pitch contours of all sentences were monotonized with the target always at 100 Hz. Three masking sentence pitch conditions were tested: (1) both at 100 Hz; (2) both at +1 semitone (106 Hz); and (3) both at +4 semitones (126 Hz). The conditions were all tested under simulated anechoic, mild, and moderate reverberation levels. Spatial release was correlated with amount of hearing loss, and decreased with increasing reverberation. Listeners in both groups were able to use the non-spatial segregation cue, pitch, to achieve lower thresholds in all spatial configurations and room conditions. Both segregation cues gave advantages, and the cues combined when both were available, due to the difficult segregation problem the experiment presented. Predictions of benefit gained from head-shadow and detriments due to audiogram thresholds were partially explained by SII model results, although all models failed to account for the variability of performance between subjects. Pitch factors were not included in the model, and thus was unable to predict the ability of subjects to use pitch. Some hearing-impaired listeners were able to get the same or more benefit from pitch as from spatial separation, suggesting non-spatial segregation cues could be exploited to improve speech intelligibility in hearing-impaired listeners in complex environments.

Author: Renita Elizabeth Sudirga
Publisher:
ISBN:
Category :
Languages : en
Pages : 314

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Previous studies provide evidence that listening experience in a particular reverberant environment improves speech intelligibility and localization performance in that environment. Such studies, however, are few, and there is little knowledge of the underlying mechanisms. The experiments presented in this thesis explored the effect of reverberation context, in particular, the similarity in interaural coherence within a context, on listeners' performance in sound localization, speech perception in a spatially separated noise, spatial release from speech-on-speech masking, and target location identification in a multi-talker configuration. All experiments were conducted in simulated reverberant environments created with a loudspeaker array in an anechoic chamber. The reflections comprising the reverberation in each environment had the same temporal and relative amplitude patterns, but varied in their lateral spread, which affected the interaural coherence of reverberated stimuli. The effect of reverberation context was examined by comparing performance in two reverberation contexts, mixed and fixed. In the mixed context, the reverberation environment applied to each stimulus varied trial-by-trial, whereas in the fixed context, the reverberation environment was held constant within a block of trials. In Experiment I (absolute judgement of sound location), variability in azimuth judgments was lower in the fixed than in the mixed context, suggesting that sound localization depended not only on the cues presented in isolated trials. In Experiment II, the intelligibility of speech in a spatially separated noise was found to be similar in both reverberation contexts. That result contrasts with other studies, and suggests that the fixed context did not assist listeners in compensating for degraded interaural coherence. In Experiment III, speech intelligibility in multi-talker configurations was found to be better in the fixed context, but only when the talkers were separated. That is, the fixed context improved spatial release from masking. However, in the presence of speech maskers, consistent reverberation did not improve the localizability of the target talker in a three-alternative location-identification task. Those results suggest that in multi-talker situations, consistent coherence may not improve target localizability, but rather that consistent context may facilitate the buildup of spatial selective attention.

Author: Michael J. Metz
Publisher: Plural Publishing
ISBN: 1597569232
Category : Medical
Languages : en
Pages : 777

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The comprehensive Sandlin's Textbook of Hearing Aid Amplification, now in its third edition, provides the hearing health professional with an overview of the technological advances related to hearing aid devices. The authors give particular emphasis to the most current advances in clinical assessment techniques and hearing instrument technology, and provide a detailed analysis of the application of digital signal processing. Clinical insights into the psychology of hearing health are included to help professionals meet clients' emotional as well as acoustic needs. This is a valuable text for academic and clinical professionals involved in the selection and fitting of hearing aid devices for the acoustically impaired. New to the third edition: Updated chapters on earmold and earshell acoustics; principles and applications of high-fidelity amplitude compression; and microphone technologyMajor revisions to chapters on digital signal processing; hearing aid selection, fitting, and verification; mathematical formulae for applying amplification; measures of validity and verification; and surgically-implanted hearing devices for unilateral hearing lossDiscussion of distribution methods; considerations for treating children; elements of design and implementation of DSP circuits; the evolution from analog to digital hearing aids; and future consideration for the field

Author: Jens Henrik Andersen
Publisher:
ISBN:
Category :
Languages : da
Pages :

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Author: Faith Christine Ypelaar Loven
Publisher:
ISBN:
Category : Speech perception
Languages : en
Pages : 616

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Author: Jens Henrik Andersen
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Ashley S. Hall
Publisher:
ISBN:
Category : Auditory perception
Languages : en
Pages : 100

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 924

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