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Relations between speech hearing and spatial hearing in normal and impaired cases
Semester I 2003
(19 May 2003)
Abstract
In experiments using normal-hearing participants the effect of
spatially separating various masking signals from a target speech
signal was examined. The maskers took the form of pairs of continuous
or discontinuous broadband noises, or speech-modulated noises, or
other speech streams. Signal-to-noise (target-to-masker) ratio
required for 90% intelligibility of the target was compared in
conditions of spatial unity - target and maskers broadcast from the
same location; versus conditions of spatial separation - target at
0°, maskers at ± 30° separation in the horizontal
plane. Spatial separation was consistently influential when the
maskers were other speech streams, suggesting that the spatial function
has a role when precise acoustic confusions arise between competing
signals.
Using a self-report procedure the relations among various hearing
functions were assessed in clients of a hearing rehabilitation
service, prior to hearing aid fitting. The hearing functions in
question comprised: speech hearing, all aspects of spatial hearing
(direction, distance, movement), signal segregation, recognition,
naturalness, clarity, and listening effort. The relations between
self-rated ability on each of these functions and a self rating of
social and emotional handicaps due to hearing impairment were also
assessed. It was found that spatial hearing disability was especially
linked with difficulty in multiple-stream speech hearing.
Furthermore, disabilities in spatial hearing, especially movement
discrimination, were prominent in the link with handicaps. A
conclusion from these two different lines of investigation is that
spatial hearing serves critically for safe orientation in the physical
environment and competence in the social environment.
