An examination of speech recognition in a modulated background and of forward masking in younger and older listeners.
OBJECTIVE
To compare speech intelligibility in the presence of a 10-Hz square-wave noise masker in younger and older listeners and to relate performance to recovery from forward masking.


METHODS
The signal-to-noise ratio required to achieve 50% sentence identification in the presence of a 10-Hz square-wave noise masker was obtained for each of the 8 younger/older listener pairs. Listeners were matched according to their quiet thresholds for frequencies from 600 to 4800 Hz in octave steps. Forward masking was also measured in 2 younger/older threshold-matched groups for signal delays of 2-40 ms.


RESULTS
Older listeners typically required a significantly higher signal-to-noise ratio than younger listeners to achieve 50% correct sentence recognition. This effect may be understood in terms of increased forward-masked thresholds throughout the range of signal delays corresponding to the silent intervals in the modulated noise (e.g., <50 ms).


CONCLUSIONS
Significant differences were observed between older and younger listeners on measures of both speech intelligibility in a modulated background and forward masking over a range of signal delays (0-40 ms). Age-related susceptibility to forward masking at relatively short delays may reflect a deficit in processing at a fairly central level (e.g., broader temporal windows or less efficient processing).
Arizona State University, Tempe, Arizona, USA. gifford.rene@mayo.edu
René H
RH
Gifford
Sid P
SP
Bacon
Erica J
EJ
Williams
D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009622:Noise; D010470:Perceptual Masking / Q000502:physiology*; D011304:Presbycusis / Q000503:physiopathology*; D013067:Speech Perception / Q000502:physiology*