Guides · Publishers
Penguin Random House audio specs, and how they differ from ACX
Publishers measure audio differently than ACX does. If you’ve only ever mastered for Audible, this is what changes when a Penguin Random House job lands in your inbox.
Penguin Random House Audio casts narrators for its backlist through its own program and the Ahab casting platform, and you get a tech spec sheet with the job. The numbers below are the ones Narration Studio ’27’s preset is built on. Publishers update their specs, though, so always check against the sheet you were actually sent. If it says something different, go with the sheet.
Side by side
| ACX / Audible | Penguin Random House | |
|---|---|---|
| Loudness | RMS -23 to -18 dB | -18 to -16 LUFS integrated |
| Peaks | -3 dB or lower (sample peak) | -1 dB or lower (true peak) |
| Noise floor | -60 dB or lower | -60 dB or lower, but no digital silence |
| Format | MP3, 192 kbps, 44.1 kHz | WAV, 44.1 kHz, 16-bit, mono |
| Room tone | 1 to 5 s at the start and end | 1 s at the start, 3 s at the end |
| Breaths | No rule, as long as they aren’t distracting | Softened, not removed |
LUFS instead of RMS
ACX measures loudness as RMS, which is a plain average of the level. Penguin Random House uses LUFS, the broadcast standard. LUFS weighs frequencies the way your ears do and skips over the quiet gaps between phrases. The two aren’t interchangeable. A file sitting comfortably inside ACX’s range can easily come out quieter than −18 LUFS. When the spec says LUFS, measure in LUFS, and don’t just reuse your ACX settings and hope.
True peak
A sample peak is the highest sample in the file. A true peak also counts the peaks that happen between samples once the audio gets turned back into sound, and those can run a little higher. So a limiter set to −1 dB sample peak can still sneak true peaks over −1. For a true peak limit you need a true-peak meter, or a limiter set a little lower to leave yourself room.
No digital silence
ACX only cares that your noise floor isn’t too high. Penguin Random House also doesn’t want it too low. Your pauses should keep their natural room tone instead of dropping to dead silence. A hard gate that mutes every pause, or edits that leave gaps of silence, can fail a publisher’s check even though ACX would’ve passed them.
Breaths: soften them, don’t delete them
Take out every breath and the narration sounds unnatural, almost breathless. Publisher specs usually want breaths turned down so they aren’t distracting, not cut out. If you use breath reduction, ease it back from where you might set it for a podcast.
WAV delivery
Publishers usually want uncompressed WAV files instead of MP3s, so they can make every retail format themselves from the best possible source. Mono is normal for a single narrator. Name the files exactly the way the spec sheet tells you to.
How I do it in Narration Studio ’27
- The Penguin Random House (PRHBL / Ahab) preset in the Mastering panel goes after the numbers above: LUFS loudness, a true-peak limit (the limiter drops lower on export if the true peak needs it), a noise floor held between −80 and −60 dB, gentler breath and noise reduction, and 44.1 kHz 16-bit mono WAV with 1 s of room tone at the start and 3 s at the end.
- Mastering › Check Compliance measures LUFS, true peak and noise floor against the preset and tells you what passes.
- The Export button shows which preset you’re on (“Export · PRH”), and its arrow switches between PRH, ACX and the rest, so the same project can go to either one.
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