A Study of Distinctive Feature Theory for Perception and Cognition and its Application to the Engineering Field

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This final project year, we have progressed substantially in the distinctive feature theory and its applications.1. Establishment of acoustic features : We studied the distinctive features applicable to the acoustic phonetic decoding (here we call this the acoustic features) in detail on its internal hierarchical structures. Back to the invariance theory of the Bloomfield's School, we examined both the phonetical and phonological feasibilities of the acoustic feature based speech recognition paradigm.2. Underlying structures across the auditory mechanism and the acoustic feature system: Human perceptual characteristics contrast with mechanical recognition characteristics, i. e. the Bayesian classifier. A reasonable hypothesis was that our acoustic feature system rules the auditory system.3. Auditory model based acoustic filtering : A model for the cochlea and the hair-cells, we have refined, agreed remarkably with a lot of physiological data. The model outperformed over conventional methods in extraction of the burst point and measurement of VOT. We developed a real time processor of this model using multiple DSPs.4. Acoustic processor for the cochlear implant : In order to hear speech processing, we coupled an acoustic simulator directly to the implantable receiver-stimulator unit. Then to the simulator attached a newly digitized processor board fully compatible with the current analog processor. Healthy people could understand heavily distorted speech never experienced before, and the distinctive features could decomposed the misperceptions. Qualifying the reasonable agreements with previous reports on performances of implanted patients, we have confirmed the fundamental basis for further developmeny of new speech processing strategies.5. Application to other languages : Effectiveness of our acoustic features is not limited to Japanese, but is generalized to other languages. The same framework was successfully applicable to French .