Apple Inc.
Microphone equalization for room acoustics

Abstract:

A microphone equalization system determines an equalization filter which is used to spectrally shape a signal from a microphone. A loudspeaker has an enclosure, a back volume, a driver diaphragm, and a sensor located inside the back volume. An external microphone is located outside the loudspeaker. A processor determines the equalization filter based on comparison of a first signal from an output of the sensor and a second signal from an output of the external microphone both of which are produced while the driver diaphragm produces acoustic pressure waves produced by the driver diaphragm. The processor is to then spectrally shape a third signal from the output of the external microphone that is responsive to further acoustic pressure waves from a source other than the loudspeaker. Other aspects are also described and claimed.