A signal internally by all digital audio devices, and externally for locking together high-end digital audio devices. Word clock is , accurate to a single sample word, usually 44.1kHz or 48kHz, i.e., the sampling rate.. Specialized hardware is required for syncing a digital audio recorder’s word clock to SMPTE timecode or some other timing reference, usually through a BNC-type connector, rather than the XLR connector used by an AES/EBU null clock signal.
See self-clocking, master clock, Super Clock.