
Touch tracks in the Logic Pro for Mac Environment
Touch tracks objects enable you to trigger MIDI regions or folders by playing a single note on your MIDI keyboard. You can use this function to play entire MIDI passages, create a new arrangement in real time, and so on, all with a single key press. Touch tracks are ideal for live performances.

You can’t use touch tracks to trigger audio. Any references to regions mean folders and MIDI regions, not audio regions. Despite this limitation, you could conceivably load your audio regions (as files) into the Sampler, and trigger it with a touch tracks object.
Here are some things to remember:
Only the touch tracks input has meaning—trigger notes must appear here. Although the object features an output triangle, it has no use, as events never appear here.
MIDI regions and folders triggered by touch tracks play exactly as they would from the main window: they play back through the instruments assigned to their tracks.
Logic Pro must be open for touch tracks to work.