Contains a summary of sound wave data for an audio file opened with WaveLab; enables faster reloading of audio files in the program; created automatically when an audio file is opened in WaveLab.

By default, WaveLab does not delete GPK files after they have been created. However, the program can be configured to automatically delete GPK files when the corresponding audio file is closed. To do this, select "Options→Preferences→File." Then select "Delete peak files when closing audio files."