Time required to classify different sound types and their relation to hearing ability and speech understanding in noise

Type of content
Theses / Dissertations
Publisher's DOI/URI
Thesis discipline
Audiology
Degree name
Master of Audiology
Publisher
University of Canterbury
Journal Title
Journal ISSN
Volume Title
Language
English
Date
2019
Authors
Budathoki, Durga Lal
Abstract

It is well known that people with sensorineural hearing loss (SNHL) have difficulties with basic auditory processing abilities such as temporal processing, frequency selectivity, frequency discrimination, as well as difficulties with complex abilities like speech perception in noise, music perception, and environmental sound awareness. The study aim of the study was to explore the procedures to reliably measure the minimum duration of sounds needed to classify the four major categories of sounds. The minimum duration of sounds needed to classify sounds was termed classification time thresholds. Another aim of the study was to investigate whether the classification time thresholds would correlate with pure tone average (PTA) thresholds. In addition, this study aimed to investigate whether the classification time thresholds would correlate with understanding of speech in noise. The classification time thresholds for classifying speech, music, noise, and animal sounds were measured in participants with normal-hearing and those with SNHL, using an adaptive 4-AFC procedure. In addition, the participants underwent pure-tone audiometry and speech in noise testing using the New Zealand matrix sentence test in auditory-alone mode.

The study showed that the participants with SNHL took longer to classify speech, noise, and music sounds. This may be due to impairment in processing abilities like temporal resolution, perception of temporal fine structure, frequency selectivity, and frequency discriminations. The study also showed that the better the ability in classifying short speech, noise, and music sounds, the better the understanding of speech in noise. This finding is consistent with glimpsing model of speech understanding in noise. Hearing ability was correlated to ageing, and to classification time thresholds. Both the effect of aging and hearing loss may cause deficits in abilities required for classifying short sounds. However, this study was unable to separate the independent effect of age and SNHL on classification time thresholds. This study may serve as an initial step towards reliably measuring classification time thresholds for participants with hearing loss and normal hearing. This study has documented the procedures that are effective and those that are problematic.

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