Click the A button at the left to view source A parameters, and click the Edit button at the right of the source filename.
The source A edit window opens.
In the waveform editor at the bottom of the main edit window, drag the E handle to the very end of the audible part of the waveform.
This effectively removes the silence at the end of the vocal phrase by reducing the playback length of the overall file.
Logic Pro Effects: PDF