Apparatus and method for matching the response of microphones in magnitude and phase
First Claim
1. A device for receiving an audible input comprising:
- a first microphone having an output responsive to the audible input;
a second microphone having an output responsive to the audible input;
a subtractor circuit responsive to the first microphone output and the second microphone output for producing a gain control output;
a circuit responsive to the first microphone output and the gain control output for producing a gain compensated microphone output;
a bandpass filter operably connected between the first microphone output and the subtractor circuit, further comprising a lowpass filter operably connected between the bandpass filter and the subtractor circuit; and
a sound level detector operably connected between the bandpass filter and the lowpass filter.
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Abstract
An apparatus is provided for matching the response of a pair of microphones. The two microphones provide a first and second output, respectively, in response to an audible input. The microphone outputs are subtract from each other to produce a gain control output for operably controlling the gain of the first microphone output, resulting in a gain compensated microphone output. A phase adjustment circuit also is provided responsive to the gain compensated microphone output and a rolloff control output for producing a matching output. The rolloff control output is generated by a phase difference subtractor circuit responsive to both the matching output and the second microphone output. Moreover, the output of at least one of the microphones has a resonance frequency that is shifted to a desired preselected frequency.
42 Citations
3 Claims
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1. A device for receiving an audible input comprising:
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a first microphone having an output responsive to the audible input;
a second microphone having an output responsive to the audible input;
a subtractor circuit responsive to the first microphone output and the second microphone output for producing a gain control output;
a circuit responsive to the first microphone output and the gain control output for producing a gain compensated microphone output;
a bandpass filter operably connected between the first microphone output and the subtractor circuit, further comprising a lowpass filter operably connected between the bandpass filter and the subtractor circuit; and
a sound level detector operably connected between the bandpass filter and the lowpass filter. - View Dependent Claims (2, 3)
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Specification
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- Resources
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Current AssigneeKnowles Electronics Llc (Knowles Corporation)
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Original AssigneeKnowles Electronics Llc (Knowles Corporation)
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InventorsThompson, Stephen C.
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Primary Examiner(s)Isen, Forester W.
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Assistant Examiner(s)Grier, Laura A.
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Application NumberUS09/193,012Time in Patent Office1,835 DaysField of Search381/104-109, 381/313, 381/97, 381/317, 381/92, 381/103US Class Current381/92CPC Class CodesH04R 25/407 Circuits for combining sign...H04R 29/006 Microphone matchingH04R 3/005 for combining the signals o...H04R 3/04 for correcting frequency re...
