Control of a loudspeaker output

摘要

A loudspeaker drive circuit has a microphone which forms part of an acoustic echo cancellation system. An input signal is processed before application to a loudspeaker driver, and the processing is controlled in dependence on the echo cancellation system performance, such as to control the extent to which the loudspeaker is driven into a non-linear operating region. In this way, the linearity can be controlled so as to provide an excursion limit, without needing a model of the loudspeaker or additional dedicated sensors.

主权项

1. A loudspeaker drive circuit comprising:
a loudspeaker driver; an input for receiving a signal from a microphone which detects the sound output of a loudspeaker having a diaphragm; a detector for detecting non-linearity between a drive signal to the loudspeaker and a microphone signal, wherein the detecting including calculating a ratio of the microphone signal and a residual signal, wherein the residual signal is calculated by subtracting the drive signal from the microphone signal; and a processor for processing an input signal before application to the loudspeaker driver, wherein the processor is adapted to alter a displacement of the diaphragm in an inverse proportion of magnitude of the detected non-linearity.