Patent ID: 6104822
Filing Date: 2000-08-15
Classification: H04R

Abstract:
A hearing aid, comprising:an input transducer for converting audio signals into analog electrical signals;an analog-to-digital converter for converting said analog signals into digital signals;a processor, capable of executing digital instructions;a memory device for storing digital data, comprising a plurality of digital signal processing means, each capable of selectively receiving said input digital signals, and each capable of generating a set of output digital signals, each of said digital signal processing means capable of processing said input digital signals to implement a selected filtering strategy designed for a selected situation, each of said digital signal processing means comprising said digital instructions, said digital instructions completely implementing each of said filtering strategies when executed by said processor, at least one of said digital signal processing means comprising:a filter bank analyzer for dividing said input digital signals into a plurality of individual frequency band signals;a multi-band processor for processing said plurality of individual frequency band signals to derive a plurality of processed frequency band signals comprising:means for generating a linear instantaneous power estimate for at least one of said individual frequency band signals to produce an instantaneous linear power estimate stream;means for converting said instantaneous linear power estimate stream into an instantaneous logarithmic power estimate stream;means for smoothing said instantaneous logarithmic power estimate stream to produce a smoothed logarithmic power estimate stream comprising:means for processing said instantaneous logarithmic power estimate stream with a smoothing coefficient time constant to derive a processed power estimate stream;means for storing a current smoothing filter state;means for processing said current smoothing filter state with said processed power estimate stream to derive a new smoothing filter state, said new smoothing filter state being stored in said storing means, and representing said smoothed logarithmic power estimate stream; andmeans for adaptively generating a new smoothing coefficient time constant based on a comparison of said current smoothing filter state with said instantaneous power estimate stream;means for calculating a gain coefficient based on said smoothed logarithmic power estimate stream; andmeans for processing said one of said individual frequency band signals and said gain coefficient to generate one of said plurality of processed frequency band signals; anda filter bank combiner for combining said plurality of processed frequency band signals to derive said output digital signals;wherein said filter-bank analyzer, said multi-band processor, and said filter bank combiner are digital instructions stored in said memory device and capable of being executed by said processor;a selector manipulatable by a user for selecting one of said digital signal processing means to use in processing said input digital signals, said selector enabling the user to dynamically select which of said filtering strategies to implement in any particular situation, each of said filtering strategies optimized for a particular listening environment;a digital-to-analog converter for converting said output digital signals into a set of output analog electrical signals; andan output transducer for converting said output analog electrical signals into a set of output audio signals.