ACX, Audible's audiobook creator platform, provides a free tool called Audio Lab that automatically checks whether an audio file meets Audible's technical requirements before a narrator or producer submits it. Creators upload their MP3 file and receive instant feedback on eight quality measurements.

Audio Lab checks files against ACX's technical submission requirements, including volume levels (RMS between -23dB and -18dB), peak levels (no higher than -3dB), noise floor (no higher than -60dB), sample rate (44.1 kHz), bitrate, and encoding format. Files that fail any automated check cannot be submitted, acting as a technical gate before the file reaches a human reviewer. ACX has described Audio Lab as a simplified version of the same automated system it uses internally for initial screening of all audiobook submissions. Files that pass the automated checks then enter a human quality control review process, which typically takes seven to fourteen business days and includes spot-checks for background noise, microphone interference, and correct chapter ordering. This two-tier approach combines signal-processing automation with a human review stage.