MediaStreamAudioDestinationNode - Web APIs
the mediastreamaudiodestinationnode interface represents an audio destination consisting of a webrtc mediastream with a single audiomediastreamtrack, which can be used in a similar way to a mediastream obtained from navigator.getusermedia.
... count 2 channel count mode "explicit" channel count interpretation "speakers" constructor mediastreamaudiodestinationnode.mediastreamaudiodestinationnode() creates a new mediastreamaudiodestinationnode object instance.

MediaStreamAudioDestinationNode.stream - Web APIs
the stream property of the audiocontext interface represents a mediastream containing a single audiomediastreamtrack with the same number of channels as the node itself.

Web Audio API - Web APIs
e processing your audio, these interfaces define where to output it.