Logic Pro X Trim or silence audio files
You use the Trim function to edit areas of the audio file that are not selected. It’s useful for removing unimportant passages—generally silence—from the start and end of your audio files. Trim can also be used to remove portions of audio files that are not used by regions.
You can use the Silence command to set all amplitude values to 0, rather than removing (with Cut, Delete, or Trim) all data from the selected area of an audio file. This function is generally used to silence unwanted background noise in quiet passages.
Trim all unselected portions of an audio file
Choose Functions > Trim from the Audio File Editor menu bar (default key command: Control-T).
Important: Make sure the areas you are about to trim (delete) do not contain any regions that you may need. Regions outside the selected area will be lost. Portions of regions that fall partly outside the selected area are also removed, resulting in a length reduction of the region. If any such regions are being used in the main window, a warning dialog will give you the option of canceling the Trim operation.
Silence the selected area of an audio file
Choose Functions > Silence from the Audio File Editor menu bar (default key command: Control-Delete).