The Beat dialog under the Dialogs menu sets the beats per minute of a TouchDesigner project. It is used by the Beat CHOP to determine its the length of its cycles and its 0-phase.
See also Tap Tempo.
When the Beat Input is set to Listen/Tap, you can tap in the beat, or tap to reset the phase of the 4-beat cycle.
To tap in the beat, first turn on the Listen button. Then press the tap button at the beginning of each bar to set the BPM. The Beat Panel will average out your taps to the closest BPM, so you can keep tapping to get a more accurate average BPM.
When the Listen button is off, pressing the tap button with reset the phase of the 4-beat cycle, effectively adjusting when the bar begins.
You can watch the beat cycle, or use the Beat CHOP to generate 0-to-1 ramps based on the beats-per-minute.
See Also: Beat CHOP.