REPORT hynek-rr-04-84/IDIAP Stochastic techniques in deriving perceptual knowledge Hermansky, Hynek EXTERNAL http://publications.idiap.ch/attachments/reports/2004/rr04-84.pdf PUBLIC Idiap-RR-84-2004 2004 IDIAP Martigny, Switzerland in Proceedings SAPA-2004, Jeju Island, Korea The paper argues on examples of selected past works that stochastic and knowledge-based approaches do not contradict each other. Frequency resolution of human hearing is decreasing with increasing frequency. Spectral basis designed for optimal discrimination among different phonemes of speech have similar property. Further, human hearing is most sensitive to modulations with frequency around 4 Hz. Filters on feature trajectories, designed for optimal discrimination among phonemes of speech are bandpass with central frequency around 4 Hz.