Spherical microphone arrays

Article By:

Elko, Gary W. Summit, New Jersey.

Meyer, Jens New York, New York.

Last reviewed:2005

DOI:https://doi.org/10.1036/1097-8542.YB050520

The most common microphone in use today is omnidirectional, meaning that it responds to signals from all directions with equal sensitivity. An omnidirectional microphone is appropriate for cellular and telephone handset use where the microphone is relatively close to the desired sound source. It is also used for specific close microphone recording of individual instruments and to record the background reverberation in sound recording. However, its use in applications where the microphone is distant from a desired speech source typically results in a recording that is too reverberant and sensitive to background room noise. A common solution for the distant microphone problem is to use a directional microphone. A directional microphone spatially filters the sound field to emphasize the desired sound signal over signals propagating from different directions. Common commercial directional microphones use a single microphone element that has openings to the sound field on both sides of the microphone membrane. Since a microphone membrane moves proportionally to the net force (the acoustic pressure difference) on the microphone, this simple mechanical design can exhibit a directional response to input acoustic waves. However, the amount of directional gain is limited, and the preferred listening direction depends on the physical orientation of the microphone.

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