Generating calibration signals for an adaptive beamformer

A method of canceling an echo generated in a hands-free communications environment having a loudspeaker and a plurality of microphones, the method comprising the steps of:

• providing a plurality of filters in correspondence with each of the microphones;
• providing a beamformer that has been calibrated for use as an acoustic echo canceler in the hands-free communications environment;
• using each one of the filters to generate an estimate of an echo signal as experienced by a corresponding one of the microphones;
• combining each of the estimated echo signals with a corresponding microphone signal, thereby generating a plurality of combined signals having reduced echo components;
• and
• using the beamformer to generate an output signal from the plurality of combined signals, wherein the output signal has further reduced echo components.

An apparatus for calibrating a beamformer for use in a hands-free communications environment having a loudspeaker and a plurality of microphones, the apparatus comprising:

• a plurality of adaptive filters in correspondence with each of the microphones;
• means for training each of the adaptive filters to model echo properties of the hands-free communications environment as experienced by the corresponding one of the microphones;
• means for supplying a first signal to the trained adaptive filters, thereby causing each of the adaptive filters to generate a jammer signal;
• means for generating combination signals by combining respective ones of the jammer signals with corresponding signals supplied by the microphones;
• and
• means for using the combination signals to adapt the beamformer to cancel the jammer signals.

An apparatus for canceling an echo generated in a hands-free communications environment having a loudspeaker and a plurality of microphones, the method comprising:

• a plurality of filters in correspondence with each of the microphones, wherein each of the filters models echo properties of the hands-free communications environment as experienced by the corresponding one of the microphones;
• a beamformer that has been calibrated for use as an acoustic echo canceler in the hands-free communications environment;
• means for supplying each of the filters with a signal that is also supplied to the loudspeaker, thereby causing each one of the filters to generate an estimate of an echo signal as experienced by a corresponding one of the microphones;
• means for combining each of the estimated echo signals with a corresponding microphone signal, thereby generating a plurality of combined signals having reduced echo components;
• and
• means for supplying the plurality of combined signals to the beamformer, thereby causing the beamformer to generate an output signal that has further reduced echo components.