AUDITORY FEATURE-EXTRACTION USING SELF-TIMED, CONTINUOUS-TIME DISCRETE-SIGNAL PROCESSING CIRCUITS

A compact integrated subsystem for accurate realtime measurement of le vel-crossing time-intervals, suitable for multiresolution feature extr action from an analog cochlear filter bank is presented. The subsystem is inspired by the function of the inner hair cells in the mammalian cochlea and is based on continuous-time discrete-signal processing cir cuits, Experimental results from a fabricated array of nine elements d emonstrate instantaneous frequency-to-voltage conversion over a range covering the audio band, The power consumption is less than 20 mu W pe r cell from a 5-V supply, when the system is biased to operate over th e speech frequency range.