Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.

Natural auditory scenes such as frog choruses consist of multiple sound sources (i.e., individual vocalizing males) producing sounds that overlap extensively in time and spectrum, often in the presence of other biotic and abiotic background noise. Detection of a signal in such environments is challe...

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Main Authors: Jozien B M Goense, Albert S Feng
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2012-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC3277502?pdf=render
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author Jozien B M Goense
Albert S Feng
author_facet Jozien B M Goense
Albert S Feng
author_sort Jozien B M Goense
collection DOAJ
description Natural auditory scenes such as frog choruses consist of multiple sound sources (i.e., individual vocalizing males) producing sounds that overlap extensively in time and spectrum, often in the presence of other biotic and abiotic background noise. Detection of a signal in such environments is challenging, but it is facilitated when the noise shares common amplitude modulations across a wide frequency range, due to a phenomenon called comodulation masking release (CMR). Here, we examined how properties of the background noise, such as its bandwidth and amplitude modulation, influence the detection threshold of a target sound (pulsed amplitude modulated tones) by single neurons in the frog auditory midbrain. We found that for both modulated and unmodulated masking noise, masking was generally stronger with increasing bandwidth, but it was weakened for the widest bandwidths. Masking was less for modulated noise than for unmodulated noise for all bandwidths. However, responses were heterogeneous, and only for a subpopulation of neurons the detection of the probe was facilitated when the bandwidth of the modulated masker was increased beyond a certain bandwidth - such neurons might contribute to CMR. We observed evidence that suggests that the dips in the noise amplitude are exploited by TS neurons, and observed strong responses to target signals occurring during such dips. However, the interactions between the probe and masker responses were nonlinear, and other mechanisms, e.g., selective suppression of the response to the noise, may also be involved in the masking release.
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spelling doaj.art-f21a05e009ea42b1b91d78ec36596eda2022-12-22T03:52:02ZengPublic Library of Science (PLoS)PLoS ONE1932-62032012-01-0172e3158910.1371/journal.pone.0031589Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.Jozien B M GoenseAlbert S FengNatural auditory scenes such as frog choruses consist of multiple sound sources (i.e., individual vocalizing males) producing sounds that overlap extensively in time and spectrum, often in the presence of other biotic and abiotic background noise. Detection of a signal in such environments is challenging, but it is facilitated when the noise shares common amplitude modulations across a wide frequency range, due to a phenomenon called comodulation masking release (CMR). Here, we examined how properties of the background noise, such as its bandwidth and amplitude modulation, influence the detection threshold of a target sound (pulsed amplitude modulated tones) by single neurons in the frog auditory midbrain. We found that for both modulated and unmodulated masking noise, masking was generally stronger with increasing bandwidth, but it was weakened for the widest bandwidths. Masking was less for modulated noise than for unmodulated noise for all bandwidths. However, responses were heterogeneous, and only for a subpopulation of neurons the detection of the probe was facilitated when the bandwidth of the modulated masker was increased beyond a certain bandwidth - such neurons might contribute to CMR. We observed evidence that suggests that the dips in the noise amplitude are exploited by TS neurons, and observed strong responses to target signals occurring during such dips. However, the interactions between the probe and masker responses were nonlinear, and other mechanisms, e.g., selective suppression of the response to the noise, may also be involved in the masking release.http://europepmc.org/articles/PMC3277502?pdf=render
spellingShingle Jozien B M Goense
Albert S Feng
Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
PLoS ONE
title Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
title_full Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
title_fullStr Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
title_full_unstemmed Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
title_short Effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons.
title_sort effects of noise bandwidth and amplitude modulation on masking in frog auditory midbrain neurons
url http://europepmc.org/articles/PMC3277502?pdf=render
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