REDUCING BACKGROUND NOISE IN COMMUNICATION SYSTEMS AND ENHANCING BINAURAL HEARING SYSTEMS FOR THE HEARING IMPAIRED

摘要

In one embodiment a conventional first order bidirectional gradient microphone (102) is employed in connection with a barrier (101) to produce sound shadow at the rearward end of the microphone (102). In other embodiments such as hearing assistive devices (7) worn on a person's head or body, the head or body of that person serves as the barrier. The result is a significant reduction in gain for all frequencies of acoustic energy emanating from generally rearward of the microphone (2). The sound shadow creates an apparent change of direction of arrival for rearwardly arriving acoustic energy, thereby making it appear to the microphone (2) that the sound is approaching from the high attenuation 90° direction. Two spaced bidirectional microphones (2) may be positioned to take advantage of this effect. A similar directional result is obtained with two conventional cardioid microphones (65) mounted on a common casing to face in opposite directions. Electronic circuitry subtracts the output signal of the rearward facing microphone (65) from the output signal of the forward facing microphone (65) to render the combination highly directional