Auditory selective adaptation moment by moment, at multiple timescales.

Abstract

Over the course of a lifetime, adults develop perceptual categories for the vowels and consonants in their native language, based on the distribution of those sounds in their environment. However, in any given listening situation, the short-term distribution of sounds can cause changes in this long-term categorization. For example, if the same sound (the "adaptor") is heard many times in a short period of time, listeners adapt and become less prone to hearing that sound. Although hundreds of speech selective adaptation experiments have been published, there is almost no information about how long this adaptation lasts.Using stimuli chosen to produce very large initial adaptation, we test adaptation effects with essentially no delay, and with delays of 25 min, 90 min, and 5.5 hr; these tests probe the duration of adaptation both in the (single) ear to which the adaptor was presented, and in the opposite ear. Reliable adaptation remains 5.5 hours after exposure in the same-ear condition, whereas it is undetectable at 90 min in the opposite ear. Surprisingly, the amount of residual adaptation is largely unaffected by whether the listener is exposed to speech between adaptation and test, unless the speech shares critical acoustic properties with the adapting sounds. Analyses of the shifts on three time scales (seconds, minutes, and hours) provide information about the multiple levels of analysis that the speech signal undergoes. Public Significance Statement: Spoken language is the primary mode of communication for most humans. The current work helps to specify the ways in which the speech signal is decoded, helping us to understand how humans accomplish this challenging task.

The contribution of visual articulatory gestures and orthography to speech processing: Evidence from novel word learning.

“…The finding obtained during the posttraining phase complements this observation. At least in the current paradigm, which used only one short training session with no specific training on phoneme perceptual discrimination, the benefit of the articulatory gestures did not persist beyond the training period, that is, when the visual cue was no longer present (see Vroomen et al, 2007 for a similar observation on perceptual learning and Samuel & Dumay, 2021, for a review).…”

Plasticity of categories in speech perception and production

“…However, selective adaptation has been found in a variety of experimental paradigms, such as following presentation of tokens in connected speech (Rudnicky & Cole, 1977). While adaptation appears to weaken over time when tested over different time intervals (Sharf & Ohde, 1981), it still can be present in some participants up to 28 minutes after exposure (Sharf & Ohde, 1981), and recent unpublished evidence indicates adaptation effects were largely intact after 25 minutes and diminished but still significant after 6 hours (Samuel & Dumay, 2021). We therefore cannot rule out the possibility that selective adaptation had an influence on our results in perception, though we highlight the work of Kleinschmidt and Jaeger (2016), who argue that selective adaptation is best seen as a form of distributional learning.…”