Why Don't Directional Microphones Work Better?By Mills, Ryan J.; Martin, Doug; Hearing Review,
Publication Date: September 2007
Article examines the benefits and limitations of digital signal processing (DSP) systems in combination with directional microphones for hearing aid users in limiting background noise. In combination, the DSP system manages the comfort level of noise using a combination of sound isolation, compression, and output limiting which maintains the level of audibility by not distorting the speech signal, while the directional microphone focuses the directionality of audition toward the signal and away from the noise. Adaptive directional microphone systems attempt to locate both the signal and the noise, focusing the directionality toward the signal, alleviating the need for the listener to look toward the signal. Two studies are outlined that sought to determine the most effective system of adaptive directionality. Results suggested that, while there seemed to be an advantage of directionality over an omnidirectional strategy, the specific type used did not seem to matter. The author suggests that the underlying reason for the limited benefit of directional microphones is that although currently available technology allows for the partial separation of signals originating from spatially distinct locations, it cannot yet duplicate the human brain and auditory system’s streaming of signals based on other physical properties of the sound such as pitch and timbre.
Published by: Ascend Media LLC (Website:http://www.ascendmedia.com)
Link to text: http://www.hearingreview.com/issues/articles/2007-09_04.asp?