Audiobook Production Glossary

A comprehensive reference for audiobook narrators, studios, and publishers.

ACX Requirements

The technical audio specifications that Audible/ACX requires for all audiobook submissions, covering sample rate, bit depth, loudness, noise floor, peak level, and file format.

Audiobook Narrator

A voice actor who performs and records the spoken audio for audiobooks, managing the entire production process from manuscript preparation through final audio delivery.

Chapter Markers

Metadata embedded in audiobook files that divide the audio into navigable chapters, allowing listeners to skip between sections on their playback device.

Crossfade

A smooth audio transition where the outgoing audio fades out while the incoming audio fades in, used at punch-in points to create seamless, click-free edits.

Digital Audio Workstation (DAW)

Software used to record, edit, and produce audio, ranging from general-purpose tools like Pro Tools and Reaper to purpose-built applications like Punch Track.

FLAC (Free Lossless Audio Codec)

A lossless audio compression format that reduces file size without sacrificing any audio quality, making it ideal for recording sessions where quality must be preserved.

Mastering

The final audio processing stage before delivery, where recorded chapters are adjusted for loudness, peak levels, noise floor, and format to meet distributor specifications.

Mouth Clicks

Unwanted clicking or sticky sounds caused by saliva and tongue movement during recording, one of the most common quality issues in audiobook narration.

Noise Floor

The level of background noise present in a recording when no one is speaking, with ACX requiring -60dB or lower for audiobook submissions.

Open Record (Roll Record)

A recording method where the narrator records straight through the entire chapter without stopping, planning to edit out mistakes in post-production.

Per Finished Hour (PFH)

The standard payment unit in audiobook production, representing the rate paid for each hour of final, mastered audio delivered.

Pickup

A section of an audiobook chapter that a reviewer or proofer has flagged for re-recording, typically due to mispronunciation, wrong emphasis, or a missed line.

Proofer

A person who listens through recorded audiobook chapters to identify errors, mark pickups, and verify that the narration matches the manuscript accurately.

Punch-and-Roll Recording

A recording technique where the narrator listens back to the last few seconds of audio before seamlessly re-recording from the point of a mistake, producing a clean, edit-free take in real time.

RMS Level

Root Mean Square level measures the average perceived loudness of an audio signal, with ACX requiring audiobook chapters to fall between -23dB and -18dB RMS.

Room Tone

The natural ambient sound of a recording space captured with no one speaking, used as a reference for noise floor measurement and to fill gaps in edited audio.

Sample Rate

The number of times per second an audio signal is measured during digital recording, with 44.1 kHz being the industry standard for audiobook production.

Sibilance

Harsh, piercing “s” and “sh” sounds in recorded speech caused by high-frequency energy concentration, often managed through microphone technique and de-essing.

Slate

A verbal identification spoken at the beginning of a recording take, typically including the chapter number, page, and take number to help organize audio during editing.

Audiobook Production Glossary | Punch Track