Multichannel Signal

A communication signal that conveys information simultaneously through multiple independent or semi-independent channels. In the context of sign languages, a multichannel signal includes the concurrent streams produced by a signer: manual signs (dominant and non-dominant hand movements, locations, and handshapes), facial expressions, eye gaze direction, head movements, and body posture. These channels may be coordinated (temporally aligned to convey related meaning) or non-coordinated (operating independently). The multichannel nature of sign languages is what makes them fundamentally different from spoken languages for computational processing — spoken language can be approximated as a single sequential channel (a string of words), while sign language requires representations that capture the temporal relationships between multiple parallel channels.