Conferencing Device Self Test
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Accused Products
Abstract
A plurality of acoustic sensors in a non-anechoic environment are calibrated with the aim of removing manufacturing tolerances and degradation over time but preserving position-dependent differences between the sensors, The sensors are excited by an acoustic stimulus which has either time-dependent characteristics or finite duration. The calibration is to be based on diffuse-field excitation only, in which indirect propagation (including single or multiple reflections) dominate over any direct-path excitation. For this purpose, the calibration process considers only a non-initial portion of sensor outputs and/or of an impulse response derived there-from. Based on these data, a frequency-dependent magnitude response function is estimated and compared with a target response function, from which a calibration function is derived.
5 Citations
25 Claims
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1-16. -16. (canceled)
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17. A method of operating a plurality of acoustic sensors arranged in a non-anechoic environment, the method comprising the steps of:
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exciting each acoustic sensor by producing, in the non-anechoic environment, an acoustic stimulus comprising a noise burst of finite duration, and concurrently sensing an output from each acoustic sensor only during a time period beginning a finite interval after the end of the acoustic stimulus; computing a frequency-dependent magnitude response function of each acoustic sensor based on at least a non-initial portion of the output from each acoustic sensor, said computation being based on the sensed output from the acoustic sensor and a spectral composition of the noise burst; and deriving a frequency-dependent calibration function based on a comparison of the magnitude response functions thus obtained and a target response function which is common to all acoustic sensors. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. A controller connectable to a plurality of acoustic sensors arranged in a non-anechoic environment and to at least one audio source in the non-anechoic environment, the controller comprising:
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a measuring section configured to excite each acoustic sensor by causing the at least one audio source to produce an acoustic stimulus comprising a noise burst of finite duration and, concurrently herewith, to capture respective outputs from the acoustic sensors by activating the acoustic sensors; a windowing section configured to extract a non-initial time segment from the output from each acoustic sensor during a time interval beginning a finite interval after the end of the acoustic stimulus; a magnitude response estimator configured to estimate a frequency-dependent magnitude response function of each acoustic sensor based on at least a non-initial portion of the output from each acoustic sensor supplied by the windowing section and on a spectral composition of the noise burst; and a calibrator configured to derive, for each audio sensor, a frequency-dependent calibration function based on a comparison of the magnitude response function of the sensor and a target response function which is common to all acoustic sensors.
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Specification