Biology subjects

Varnet, L.

Publications and source records attributed to Varnet, L..

3 recordsLinked to original sources

bioRxiv2022

A microscopic investigation of the effect of random envelope fluctuations on phoneme-in-noise perception

In this study, we investigated the effect of specific noise realizations on the discrimination of two consonants, /b/ and /d/. For this purpose, we collected data from twelve participants, who listened to the words /aba/ or /ada/ embedded in one of three background noises. All noises had the same long-term spectrum but differed in the amount of random envelope fluctuations. The data were analyzed on a trial-by-trial basis using the reverse-correlation method. The results revealed that it is possible to predict the categorical responses with better-than-chance accuracy purely based on the spectro-temporal distribution of the random envelope fluctuations of the corresponding noises, without taking into account the actual targets or the signal-to-noise ratios used in the trials. The effect of the noise fluctuations explained on average 8.1% of the participants responses in white noise, a proportion that increased up to 13.3% for noises with a larger amount of fluctuations. The estimated time-frequency weights revealed that the measured effect originated from confusions between noise fluctuations and relevant acoustic cues from the target words. Substantially similar conclusions were obtained from simulations using an artificial listener. We argue that this token-specific effect of noise is a form of informational masking.

animal behavior and cognition↗

bioRxiv2022

Subcortical and cortical tracking of communication sound envelopes in challenging listening conditions

Humans and animals constantly face challenging acoustic environments such as various background noises restricting the detection, discrimination and identification of behaviorally salient sounds. Here, we disentangled the role of temporal envelope tracking on the decrease in neuronal and behavioral discrimination between communication sounds in situations of acoustic degradations. We simulated responses of auditory nerve fibers and recorded neuronal activity in cochlear nucleus, inferior colliculus, thalamus and auditory cortex in anesthetized guinea-pigs. Furthermore, a Go/No-Go sound discrimination task involving two of the guinea-pig whistles was performed on mice in silence and noise. For all conditions, we found that auditory neurons better track the slow amplitude modulations (<20 Hz) of the stimulus envelopes than the faster ones. In addition, the decrease in neuronal and behavioral discrimination performance in noise can be explained by an increased similarity of the vocalization envelopes in the low frequency range (<20 Hz). Together, these results suggest that slow envelope tracking is a general property of auditory neurons, and any difference between the slow envelopes of natural stimuli allows coping with degraded conditions.

neuroscience↗

bioRxiv2020

Mechanisms of spectrotemporal modulation detection for normal- and hearing-impaired listeners

Spectrotemporal modulations (STMs) offer a unified framework to probe suprathreshold auditory processing. Here, we introduce a novel methodological framework based on psychophysical reverse-correlation deployed in the modulation space to characterize how STMs are detected by the auditory system and how cochlear hearing loss impacts this processing. Our results show that young normal-hearing (NH) and older hearing-impaired (HI) individuals rely on a comparable non-linear processing architecture involving non-directional band-pass modulation filtering. We demonstrate that a temporal-modulation filter-bank model can capture the strategy of the NH group and that a broader tuning of cochlear filters is sufficient to explain the overall shift toward temporal modulations of the HI group. Yet, idiosyncratic behaviors exposed within each group highlight the contribution and the need to consider additional mechanisms. This integrated experimental-computational approach offers a principled way to assess supra-threshold auditory processing distortions of each individual.

neuroscience↗