Adaptive, programmable signal processing and filtering for hearing aids

Claims

What is claimed is:

1. A digital signal processing hearing aid system comprising:

(a) input means for providing an electrical input signal corresponding to a sound signal;

(b) analog to digital converter means for converting the input signal from the input means to input signal digital data at a selected sample rate;

(c) digital signal processing means for receiving the input signal digital data from the analog to digital converter means and providing processed output data, the digital signal processing means including:

(1) means for analyzing the input signal data and estimating the energy contained in a plurality of selected frequency bands which cover the range of frequency content of the input signal data, wherein the means for analyzing the input signal data includes a first high pass digital filter for passing the higher half of the input signal frequency range, a first low pass digital filter for passing the lower half of the input signal frequency range and providing a second frequency range signal data, a second high pass digital filter selected to pass the higher half of the second frequency range signal and a second low pass digital filter selected to pass the lower half of the second frequency range signal to provide a third frequency range signal, a third high pass digital filter selected to pass the higher half of the third frequency range signal and a third low pass digital filer selected to pass the lower half of the third frequency range signal to provide a fourth frequency range signal, the fourth high pass filter selected to pass the higher half of the fourth frequency range signal and a fourth low pass digital filter selected to pass the lower half of the fourth frequency range signal, and wherein the means for analyzing further includes means for estimating the energy in the data corresponding to the outputs of the first, second, third, and fourth high pass filters and the fourth low pass filter;

(2) gain calculation means for calculating a gain for each band which is a function of estimated energy in each band;

(3) digital spectral filter means, having a plurality of filter coefficients which are changeable, for receiving the input signal digital data and providing spectrally shaped output data for output from the digital signal processing means;

(4) coefficient calculation means for calculating the coefficients of the digital spectral filter means based on the gains for each band calculated by the gain calculation means, the coefficients of the digital spectral filter means being periodically changed to the new coefficients calculated by the coefficient calculation means;

(d) digital to analog converter means for converting the processed output data from the digital signal processing means to an analog signal; and

(e) means for converting the analog signal to a corresponding sound.

2. The hearing aid system of claim 1 wherein the means for estimating the energy in the frequency bands of the input signal data further comprises means for taking the absolute values of the