Salle des Voûtes, Campus St Charles - 11H - 13003 Marseille
Christian Lorenzi,
CNRS & Ecole normale supérieure, Paris,

Processing time with our auditory system

Debate on how speech information is represented in the auditory system has revolved around the role of two neural/perceptual features encoding the temporal modulations of the acoustic signal (the “temporal envelope”, ENV, and “temporal fine structure”, TFS), their relative contribution to intelligibility and how that might be degraded by lesions to the peripheral and central auditory system. We will review psychophysical studies that investigated the development of ENV/TFS perception, the effects of cochlear and central lesions, and the relationship between ENV/TFS perception and speech intelligibility. Our results suggest that: i) the processing of ENV and TFS is “functional” by 6 months, and fine-tuned by language exposure between 6 and 10 months, ii) ENV is more important for speech identification, whereas TFS is more important for the segregation of competing sound sources, iii) reduced ability to process ENV and/or TFS explains deficits typically associated with cochlear and central damage and ageing.

*References: *
Shamma, S., & Lorenzi, C. (2013). On the balance of envelope and temporal fine structure in the encoding of speech in the early auditory system. /Journal of the Acoustical Society of America, 133, /2818-2833/./
Lorenzi, C., Debruille, L., Garnier, S., Fleuriot, P., & Moore, B.C.J. (2009). Abnormal auditory temporal processing for frequencies where absolute thresholds are normal. /Journal of the Acoustical Society of America, 125, 27-30./
Lorenzi, C., Gilbert, G., Carn, H., Garnier, S., & Moore, B.C.J. (2006). Speech perception problems of the hearing impaired reflect inability to use temporal fine structure. /Proceedings of the National Academy of Science/ /USA/, /103(49)/, 18866-18869.