Patent ID: 7409068
Filing Date: 2008-08-05
Classification: H04R

Abstract:
1. A hearing instrument, comprising: a front microphone that generates a front microphone signal; a rear microphone that generates a rear microphone signal; a phase-shifting circuit that implements a frequency-dependent phase shift between the front microphone signal and the rear microphone signal to create a controlled loss in directional gain and maintain a predetermined maximum level of microphone self noise amplification (G the frequency-dependent phase shift being configured to provide a maximum amount of directional gain given the predetermined maximum level of microphone self noise amplification (G the frequency-dependent phase shift (θ wherein the frequency-dependent phase shift (θ where ω is the radian frequency (2πf), d is the spacing between the front and rear microphones, v is the speed of sound, and x is a function of the predetermined maximum level of microphone self noise amplification (G N ).