Biology subjects

Varnet, L.

Publications and source records attributed to Varnet, L..

5 recordsLinked to original sources

bioRxiv2025

FastACI: A Toolbox for Investigating Auditory Perception using Reverse Correlation

The fastACI toolbox provides a compilation of tools for collecting and analyzing data from auditory reverse-correlation experiments. These experiments involve behavioral listening tasks including one or more target sounds presented with some random fluctuation, typically in the form of additive background noise. In turn, the paired stimulus-response data from each trial can be used to assess the relevant acoustic features that were effectively used by the listener while performing the task. The results are summarized as a matrix of perceptual weights termed auditory classification image. The framework provided by the toolbox is flexible and it has been so far used to probe different auditory mechanisms such as tone-in-noise detection, amplitude modulation detection, phoneme-in-noise categorization, and word segmentation. In this article, we present the structure of the toolbox, how it can be used to run existing experiments or design new ones, as well as the main options for analyzing the collected data. We then illustrate the capabilities of the toolbox through five case studies: a replication of a pioneering reverse correlation study from 1975, an example of reproduction of the analyses of one of our previous studies, a comparison of the results of three phoneme-categorization experiments, and a quantification of how noise type and estimation method affect the quality of the resulting auditory classification image.

neuroscience↗

bioRxiv2024

Mapping the spectrotemporal regions influencing perception of French stop consonants in noise

Understanding how speech sounds are decoded into linguistic units has been a central research challenge over the last century. This study follows a reverse-correlation approach to reveal the acoustic cues listeners use to categorize French stop consonants in noise. Compared to previous methods, this approach ensures an unprecedented level of detail with only minimal theoretical assumptions. Thirty-two participants performed a speech-in-noise discrimination task based on natural /aCa/ utterances, with C = /b/, /d/, /g/, /p/, /t/, or /k/. The trial-by-trial analysis of their confusions enabled us to map the spectrotemporal information they relied on for their decisions. In place-of-articulation contrasts, the results confirmed the critical role of formant consonant-vowel transitions, used by all participants, and, to a lesser extent, vowel-consonant transitions and high-frequency release bursts. Similarly, for voicing contrasts, we validated the prominent role of the voicing bar cue, with some participants also using formant transitions and burst cues. This approach revealed that most listeners use a combination of several cues for each task, with significant variability within the participant group. These insights shed new light on decades-old debates regarding the relative importance of cues for phoneme perception and suggest that research on acoustic cues should not overlook individual variability in speech perception.

neuroscience↗

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↗