I think 'speed' means that the sound recording is in sync or at the same 'speed' as the camera recording. Here in the UK, the sound recordist tells the boom operator and they announce it, shortly after the 1st Assistant Director calls 'turn over' to get the camera to start recording.
sexytalk128 t1_iu5z0ob wrote
Reply to comment by GoGaslightYerself in TIL, in film, a clapperboard’s purpose is ensuring proper synchronization of audio and video in post-production. It provides a distinct “clap” along with a visual event for the editor to reference at the start of a scene. by PianoCharged
I think 'speed' means that the sound recording is in sync or at the same 'speed' as the camera recording. Here in the UK, the sound recordist tells the boom operator and they announce it, shortly after the 1st Assistant Director calls 'turn over' to get the camera to start recording.