Frequency Selectivity and Comodulation Masking Release in Adults and in 6-Year-Old Children

1990 ◽  
Vol 33 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Kathleen Veloso ◽  
Joseph W. Hall ◽  
John H. Grose
Keyword(s):  
Frequency Selectivity ◽  
Center Frequency ◽  
Signal Frequency ◽  
Noise Masking ◽  
Masking Release ◽  
Noise Masker ◽  
Wideband Noise ◽  
Masking Noise ◽  
Comodulation Masking Release ◽  
Narrowband Noise

Frequency selectivity and comodulation masking release (CMR) for a 1000-Hz signal frequency were examined in 6-year-old children and adults. An abbreviated measure of frequency selectivity was also conducted for a 500-Hz signal. Frequency selectivity was measured using a notched-noise masking method, and CMR was measured using narrow bands of noise whose amplitude envelopes were either uncorrelated or correlated. There were 6 listeners in each age group. No differences were observed between the adults and children for either auditory measure. Similarly, no differences were observed in the ability to detect a pure-tone signal in a relatively wideband noise masker. When the masking noise was narrowband, however, the masked thresholds of the children were higher than those of the adults. Two characteristics that distinguish narrowband noise from wideband noise are: (1) narrowband noise has a pitch quality corresponding to its center frequency, whereas wideband noise does not have a definite pitch; (2) the intensity fluctuations are relatively greater in narrowband noise than in wideband noise. This may suggest that 6-year-old children have a reduced ability to detect signals in noise backgrounds where the signal has perceptual qualities similar to the noise, or in noise backgrounds having a high degree of fluctuation.

Influence of Frequency Selectivity on Comodulation Masking Release in Normal-Hearing Listeners

1993 ◽  
Vol 36 (2) ◽  
pp. 410-423 ◽  
Author(s):  
Joseph W. Hall ◽  
John H. Grose ◽  
Brian C. J. Moore
Keyword(s):  
Normal Hearing ◽  
Frequency Selectivity ◽  
Frequency Separation ◽  
Signal Frequency ◽  
Noise Background ◽  
Masker Level ◽  
Reduced Frequency ◽  
Comodulation Masking Release ◽  
Comodulated Noise ◽  
Signal Band

Experiments 1 and 2 investigated the effect of frequency selectivity on comodulation masking release (CMR) in normal-hearing subjects, examining conditions where frequency selectivity was relatively good (low masker level at both low [500-Hz] and high [2500-Hz] signal frequency, and high masker level at low signal frequency) and where frequency selectivity was somewhat degraded (high masker level and high signal frequency). The first experiment investigated CMR in conditions where a narrow modulated noise band was centered on the signal frequency, and a wider comodulated noise band was located below the band centered on the signal frequency. Signal frequencies were 500 and 2000 Hz. The masker level and the frequency separation between the on-signal and comodulated flanking band were varied. In addition to conditions where the flanking band and on-signal band were presented at the same spectrum level, conditions were included where the spectrum level of the flanking band was 10-dB higher than that of the on-signal band, in order to accentuate effects of reduced frequency selectivity. Results indicated that CMR was reduced at the 2000-Hz region when masker level was high, when the frequency separation between on-signal and flanking band was small, and when a 10-dB level disparity existed between the on-signal and flanking band. In the second experiment, CMR was investigated for narrow comodulated noise bands, presented either without any additional sound or in the presence of a random noise background. CMR increased slightly as the masker level increased, except at 2500 Hz when the noise background was present. The decrease in CMR at 2500 Hz with the high masker level and with a noise background present could be explained in terms of reduced frequency selectivity. In a third experiment, we compared performance for equal absolute bandwidth maskers at a low (500-Hz) and a high (2000-Hz) stimulus frequency. Results here suggested that detection in modulated noise may be reduced due to a reduction in the number of quasi-independent auditory filters contributing temporal envelope information. The effects found in the present study using normal-hearing listeners under conditions of degraded frequency selectivity may be useful in understanding part of the reduction of CMR that occurs in cochlear-impaired listeners having reduced frequency selectivity.

scholarly journals Ecological validity of masking release with speech-like stimuli

2021 ◽  
Author(s):  
Hyojin Kim ◽  
Viktorija Ratkute ◽  
Bastian Epp
Keyword(s):  
Speech Perception ◽  
Temporal Dynamics ◽  
Ecological Validity ◽  
Detection Thresholds ◽  
Formant Frequencies ◽  
Masking Release ◽  
Grouping Effect ◽  
Masking Level Difference ◽  
Masking Noise ◽  
Comodulation Masking Release

Comodulated masking noise and binaural cues can facilitate detecting a target sound from noise. These cues can induce a decrease in detection thresholds, quantified as comodulation masking release (CMR) and binaural masking level difference (BMLD), respectively. However, their relevance to speech perception is unclear as most studies have used artificial stimuli different from speech. Here, we investigated their ecological validity using sounds with speech-like spectro-temporal dynamics. We evaluated the ecological validity of such grouping effect with stimuli reflecting formant changes in speech. We set three masker bands at formant frequencies F1, F2, and F3 based on CV combination: /gu/, /fu/, and /pu/. We found that the CMR was little (< 3 dB) while BMLD was comparable to previous findings (~ 9 dB). In conclusion, we suggest that other features may play a role in facilitating frequency grouping by comodulation such as the spectral proximity and the number of masker bands.

Masking release for gap detection

1992 ◽  
Vol 336 (1278) ◽  
pp. 331-337 ◽  
Keyword(s):  
Random Noise ◽  
Detection Threshold ◽  
Signal Frequency ◽  
Frequency Noise ◽  
Gap Detection ◽  
Noise Masking ◽  
Level Difference ◽  
Masking Release ◽  
Masking Level Difference ◽  
Release From Masking

In random noise, masking is influenced almost entirely by noise components in a narrow band around the signal frequency. However, when the noise is not random, but has a modulation pattern which is coherent across frequency, noise components relatively remote from the signal frequency can actually produce a release from masking. This masking release has been called comodulation masking release (CMR). The present research investigated whether a similar release from masking occurs in the analysis of a suprathreshold signal. Specifically, the ability to detect the presence of a temporal gap was investigated in conditions which do and do not result in CMR for detection threshold. Similar conditions were investigated for the masking level difference (a binaural masking release phenomenon). The results indicated that suprathreshold masking release for gap detection occurred for both the masking-level difference (MLD) and for CMR. However, masking release for gap detection was generally smaller than that obtained for detection threshold. The largest gap detection masking release effects obtained corresponded to relatively low levels of stimulation, where gap detection was relatively poor.

scholarly journals Comodulation masking release in the inferior colliculus by combined signal enhancement and masker reduction

2017 ◽  
Vol 117 (2) ◽  
pp. 853-867 ◽  
Author(s):  
Jan-Philipp Diepenbrock ◽  
Marcus Jeschke ◽  
Frank W. Ohl ◽  
Jesko L. Verhey
Keyword(s):  
Inferior Colliculus ◽  
Intermediate Stage ◽  
Auditory Pathway ◽  
Current Data ◽  
Signal Frequency ◽  
Target Signal ◽  
Response Characteristics ◽  
Masking Release ◽  
Comodulation Masking Release ◽  
First Time

Auditory signals that contain coherent level fluctuations of a masker in different frequency regions enhance the detectability of an embedded sinusoidal target signal, an effect commonly known as comodulation masking release (CMR). Neural correlates have been proposed at different stages of the auditory system. While later stages seem to suppress the response to the masker, earlier stages are more likely to enhance their response to the signal when the masker is comodulated. Using a flanking band masking paradigm, the present study investigates how CMR is represented at the level of the inferior colliculus of the Mongolian gerbil. The responses to a target signal at various sound pressure levels in three different masking conditions were compared. In one condition the masker was a 10-Hz amplitude modulated sinusoid centered at the signal frequency while in the other two conditions six off-frequency carriers (flanking bands) were added. For 64 of a total of 94 units, the addition of comodulated flanking bands to the on-frequency masker did not change the response to the target signal. The remaining 30 units showed a change that enhanced target detectability if coherent flanking bands were added, indicative of CMR. The current data demonstrate that the response characteristics of these neurons represent an intermediate stage between the representation in the cochlear nucleus and the auditory cortex by increasing the response during the signal intervals and decreasing the response for the following masker portions. NEW & NOTEWORTHY The detection of comodulation, i.e., coherent level fluctuations in different frequency regions, is an important feature of speech recognition. In this study, we demonstrate how the representation of a signal in comodulated masking conditions changes along the auditory pathway by using a stimulus paradigm from the cochlea nucleus for the first time in the inferior colliculus. This happens on a timescale that makes corticocollicular feedback a likely candidate as the source.

scholarly journals The effect of the preceding masking noise on monaural and binaural release from masking

2021 ◽  
Author(s):  
Hyojin Kim ◽  
Viktorija Ratkute ◽  
Bastian Epp
Keyword(s):  
Cochlear Nucleus ◽  
Temporal Integration ◽  
System Level ◽  
Top Down ◽  
Detection Thresholds ◽  
Masking Release ◽  
Masking Level Difference ◽  
Masking Noise ◽  
Comodulation Masking Release ◽  
Release From Masking

When a target tone is preceded by a noise, the threshold for target detection can be increased or decreased depending on the type of a preceding masker. The effect of preceding masker to the following sound can be interpreted as either the result of adaptation at the periphery or at the system level. To disentangle these, we investigated the time constant of adaptation by varying the length of the preceding masker. For inducing various masking conditions, we designed stimuli that can induce masking release. Comodulated masking noise and binaural cues can facilitate detecting a target sound from noise. These cues induce a decrease in detection thresholds, quantified as comodulation masking release (CMR) and binaural masking level difference (BMLD), respectively. We hypothesized that if the adaptation results from the top-down processing, both CMR and BMLD will be affected with increased length of the preceding masker. We measured CMR and BMLD when the length of preceding maskers varied from 0 (no preceding masker) to 500 ms. Results showed that CMR was more affected with longer preceding masker from 100 ms to 500 ms while the preceding masker did not affect BMLD. In this study, we suggest that the adaptation to preceding masking sound may arise from low level (e.g. cochlear nucleus, CN) rather than the temporal integration by the higher-level processing.

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