Forward masking of amplitude modulation: Basic characteristics

Magdalena Wojtczak, Neal F. Viemeister

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

In this study we demonstrate an effect for amplitude modulation (AM) that is analogous to forward making of audio frequencies, i.e., the modulation threshold for detection of AM (signal) is raised by preceding AM (masker). In the study we focused on the basic characteristics of the forward-masking effect. Functions representing recovery from AM forward masking measured with a 150-ms 40-Hz masker AM and a 50-ms signal AM of the same rate imposed on the same broadband-noise carrier, showed an exponential decay of forward masking with increasing delay from masker offset. Thresholds remained elevated by more than 2 dB over an interval of at least 150 ms following the masker. Masked-threshold patterns, measured with a fixed signal rate (20, 40, and 80 Hz) and a variable masker rate, showed tuning of the AM forward-masking effect. The tuning was approximately constant across signal modulation rates used and consistent with the idea of modulation-rate selective channels. Combining two equally effective forward maskers of different frequencies did not lead to an increase in forward masking relative to that produced by either component alone. Overall, the results are consistent with modulation-rate selective neural channels that adapt and recover from the adaptation relatively quickly.

Original languageEnglish (US)
Pages (from-to)3198-3210
Number of pages13
JournalJournal of the Acoustical Society of America
Volume118
Issue number5
DOIs
StatePublished - Nov 2005

Bibliographical note

Funding Information:
We thank the editor Gerald Kidd, Jr., and two anonymous reviewers for their helpful comments on an earlier version of this paper. This work was supported by NIH/NIDCD Grant No. DC00683 and Grant No. DC006804.

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