A method to manufacture a dual-port audio product implementing a selective mixing feature, comprising:
- providing a first communication port configured to receive and transmit far-side audio data to a distant party, wherein said first communication port is operable in a full-duplex mode;
- providing a second communication port configured to receive audio data, said second port optionally configured to transmit audio data to another distant party;
- coupling a first mixer to said first and second communication ports, said first mixer receiving audio data from said first and second communication ports, wherein said first mixer is configured to mix the audio received from said first and second communication ports;
- coupling a sound producing circuit to said first mixer, said sound producing circuit receiving an audio signal from said first mixer, wherein said sound producing circuit and said first mixer are configured to produce an audible sound corresponding to a mixed signal of the audio data received from said first and second communication ports;
- providing a microphone circuit configured to receive audible sounds, said microphone circuit further configured to convert said audible sounds to an audio signal;
- providing a far-side frequency decomposer operable to decompose the far-side audio data received from said first communication port;
- providing a microphone frequency decomposer operable to decompose the audio data received at said microphone circuit into a number of frequency bands;
- providing an acoustic echo canceller receiving the audio signal produced by said microphone circuit and a mixed audio signal mixed from the audio data received at said first and second communication ports, wherein said echo canceller is operable to apply an echo cancellation filter to the mixed audio signal to generate an echo cancelled signal;
- wherein the echo signal corresponding to the audio signal between said sound producing circuit and said microphone circuit is attenuated in the echo cancelled signal,
- providing a second mixer configured to receive the echo cancelled signal produced from said echo canceller and audio data from said second communication port, wherein said second mixer is operable to mix the echo cancelled signal and an incoming audio data from said second communication port into an outgoing audio signal to said first communication port;
- providing a switch interposed between said second communication port and said second mixer, wherein said switch may be configured to pass or block the incoming audio data from said second communication port, further wherein where said switch is configured to pass audio data said second mixer operates to mix the audio data from said second communication port and the echo cancelled signal, further wherein where said switch is configured to block audio data said second mixer operates to pass only the echo cancelled signal to said first communication port and not the audio signal received at said second communication port;
- providing an audio subsystem that implements doubletalk detection and recovery using information received from said frequency decomposers;
- and
- providing a control input for said switch, whereby the operation of said product can be selected between mix mode and non-mix mode;
- wherein the echo cancelled signal is provided to said first communication port without mixing the audio received from said second audio port, such that the conversational distant party does not hear the audio signal received at said second communication port because it is not mixed in the outgoing signal of said first port and that signal is echo cancelled by said acoustic echo canceller.