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Discrimination of the phase of amplitude modulation applied to different carriers: Effects of modulation rate and modulation depth for young and older subjects.

Accepted version
Peer-reviewed

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Type

Article

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Authors

Moore, Brian CJ 
Sęk, Aleksander P 

Abstract

The discrimination of amplitude modulation (AM) from frequency modulation (FM) of a 1000-Hz carrier, with equally detectable AM and FM, is better for a 2-Hz than for a 10-Hz modulation rate. This might reflect greater sensitivity to temporal fine structure for low than for high rates. Alternatively, AM-FM discrimination may depend on comparing fluctuations in excitation level on the two sides of the excitation pattern, which are in phase for AM and out of phase for FM. Discrimination of the relative phase of fluctuations might worsen with increasing rate, which could account for the effect of rate on AM-FM discrimination. To test this, discrimination of the phase of AM applied to two sinusoidal carriers was assessed, with a band of noise between the two carriers to prevent use of within-channel cues. Young and older subjects with normal hearing were tested. Performance was almost constant for AM rates from 2 to 10 Hz, but worsened at 20 Hz. Performance was near chance for AM depths near the detection threshold. The results suggest that the superior AM-FM discrimination at 2 Hz cannot be explained in terms of comparison of the phase of fluctuations on the two sides of the excitation pattern.

Description

Keywords

Acoustic Stimulation, Adult, Aged, Aging, Auditory Threshold, Female, Hearing, Humans, Male, Middle Aged, Pitch Discrimination

Journal Title

J Acoust Soc Am

Conference Name

Journal ISSN

0001-4966
1520-8524

Volume Title

146

Publisher

Acoustical Society of America (ASA)

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/M026957/1)