Patent ID: 6292571
Filing Date: 2001-09-18
Classification: H03H,H04R

Abstract:
A system for processing digital signals of a hearing aid device, the system comprising:an audio input signal representative of a sound level;a digital filter for processing the audio input signal, the digital filter including coefficient multipliers to provide selective weighting of discrete components derived from the input signal at stages of the digital filter, the coefficient multipliers supporting coefficient multiplication via bit-shifting to produce selected weights of corresponding discrete components at stages of the digital filter; andan output of the digital filter, the output depending at least in part on the coefficient multiplication of components at corresponding stages of the digital filter, at least one stage of the digital filter including a multiplier circuit, a selected multiplicand input of the multiplier circuit controlling a corresponding frequency response such that the digital filter provides a frequency response about that provided by transfer function H(z)=-z.sup.-2 +.lambda.(-2.sup.-.gamma. z.sup.-2 +G(z).sup.S), where G(z)=(0.5+0.5 z.sup.-1 +0.125z.sup.-2) (1+0.25z.sup.-1) (1-z.sup.-1), and where .gamma. controls the magnitude of the frequency response at a higher frequency range, and .gamma. controls the magnitude of the frequency response at lower frequency range, and S selects a slope of the frequency response between the high and low frequency ranges.