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Abstract
In order to recognize speech, human listeners use cues distributed across different frequencies. Frequency-importance functions, which indicate the relative importance of different frequency bands for speech recognition, are an essential ingredient of predictive models of speech intelligibility, such as the articulation index. They can also be useful for optimizing multi-band speech-processing devices (e.g., current hearing aids). Traditionally, frequency-importance functions have been assessed using low- and high-pass filtered speech. However, this approach has some limitations. An alternative approach, pioneered by Doherty and Turner (J. Acoust. Soc. Am. 100, 1996), uses wide-band speech, to which random perturbations (noise) are added independently in different bands. The importance of each band is then estimated based on the correlation between the signal-to-noise ratios applied successively in that band and the corresponding binary recognition scores, across thousands of trials. In this talk, I will review results obtained with this perturbation-correlation approach. In particular, I will show how the approach may be used to gain insight into the strategies used by listeners to recognize speech in different kinds of acoustic backgrounds (noise versus competing speech). I will also address the question of inter-listener variability and the influence of hearing loss. Finally, I will describe my recent efforts to better understand the theoretical (mathematical) basis of the perturbation-correlation method as applied to speech, in an attempt to improve it. [Work done in collaboration with Gatan Gilbert, CNRS UMR 5020, Lyon, France]

Biography
I obtained a PhD in Experimental and Cognitive Psychology from Lumiere University (Lyon, France) in 1995. From 1996 to 1997 I was as a Research Associate in the Department of Experimental Psychology of Cambridge University (Cambridge, UK), and a Visiting Scientist in the Medical Research Council Cognition and Brain Sciences Unit (MRC-CBU). I worked there with Bob Carlyon and Brian Moore for a total of three years. After being offered a tenure position by the French Centre National de la Recherche Scientifique (CNRS), I went back to Lyon for about three years. I came over to the US in 2001. After a short stay in Pr. Rauscheckers lab at Institute for Cognitive and Computational Sciences, Georgetwon University (Washington, DC), I joined Andrew Oxenhams group in the Research Laboratory of Electronics, Massachusetts Institute of Technology (Cambridge, MA), where I am currently a Research Scientist