Modulation analysis of speech through orthogonal FIR filterbank optimization

Newborns must learn to structure incoming acoustic information into segments, words, phrases, etc., before they can start to learn language. This process is thought to rely on modulation structure of the speech waveform induced by segmental or prosodic regularities within the speech heard by the infant. Here, we investigate the process by which the initial acoustic processing required by modulation analysis can itself be tuned by exposure to the regularities of speech. Starting from the classic definition of modulation, as applied within channels of the peripheral filter, we formulate a mathematical framework in which the structure of initial spectral filtering is adapted for modulation analysis. Our working hypothesis is that the human ear and brain are adapted to the analysis of modulation, via a data-driven learning process on the scale of development (or possibly evolution). Simulation results are presented and a comparison with filterbanks classically used in signal processing is done.