voice guidance; voice guide; audio guide; spoken instructions
synthesized voice; synthesized speech
second (supplementary) sound channel
voice recognition; speech recognition
spoken instructions (over the phone, etc.); voice assist; spoken directions
voice guidance; voice guide; audio guide; spoken instructions
speech output; voice output; audio output
speech synthesis; voice synthesis
mixing board (console, desk); (audio) mixer
multiplex broadcast or transmission
phonetic transcription; phonetic notation
International Phonetic Alphabet; IPA