Audi-book
Record, edit and export your audiobook in the Studio, on your device, then measure loudness, true peak, noise and bit rate against the ACX requirements.
This application runs sandboxed on your own device.
About this tool
Audi-book brings two parts together. The Studio, from manuscript to voice: record each chapter, edit your takes, export MP3, WAV or M4B; the project stays on your device, and only the AI voice, when enabled, goes through the site's server. Then the ACX check, before you upload your files:
An audiobook is refused on figures an author cannot see. Audi-book measures them, every file at once, without anything leaving your device.
Loudness to the ITU-R BS.1770 standard — the unit the platforms speak in. True peak, the one that exists BETWEEN two samples: that is how a file showing −0.1 dB ends up clipping once converted to MP3, and no ordinary meter shows it. The noise floor, mains hum at 50 or 60 Hz, rumble below 80 Hz, and the real bandwidth — which gives away a “high quality” file actually made from a low-bitrate MP3.
Drop the whole book at once: Audi-book compares the chapters against each other. A chapter recorded on another day, three decibels louder, is heard as a step at every change — the commonest complaint about a self-produced audiobook, and visible only from one file to the next.
Every measurement is then set against the ACX requirements, taken from help.acx.com on 6 September 2026 and checked twice: peak, average volume, noise floor, format, sample rate, constant bit rate, length, room tone, channel consistency. The units are ACX’s and no others: where it writes “dB RMS”, nothing is converted into LUFS.
Three states only — blocking, to fix, advice. Never “compliant”. Audi-book decides nothing: only ACX decides.
The report downloads as HTML or as a CSV table, to file away or send to your narrator.