Author’s Republic asks for chapter files between -23 and -18 dB RMS, with peaks no higher than -3 dB, a noise floor at or below -60 dB RMS, and 192 kbps or higher constant bit rate MP3 at 44.1 kHz, plus rules on silence, file size and chapter length. WavSpec checks a whole audiobook folder against those numbers in one pass on Windows, using its built-in Author’s Republic audiobook preset, corrects the levels and format, and writes a report. Some items on the list are about content and editing, and those still need your ears.
This guide sets out the full list as Author’s Republic publishes it, separates the items a tool can measure from the ones it cannot, and shows a batch workflow for checking before you upload.
Check every chapter against the Author’s Republic numbers before you upload.
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What are the Author’s Republic audio requirements?
Author’s Republic publishes an Audio Requirements List in its help center and explains it in a blog post, Understanding Audio Requirements. Here is the list grouped by type.
| Requirement | Author’s Republic value | Measurable by software? |
|---|---|---|
| Average loudness | Between -23 dB and -18 dB RMS | Yes |
| Peak level | No higher than -3 dB | Yes |
| Noise floor | No higher than -60 dB RMS | Yes |
| File format | MP3 | Yes |
| Bit rate | 192 kbps or higher, constant bit rate (CBR) | Yes |
| Sample rate | 44.1 kHz | Yes |
| File size | 170 MB or less per file | Yes |
| Length per file | 119 minutes or less | Yes |
| Silence at start and end | 1 to 5 seconds of silence | Yes, the length |
| Channels | All files mono or all stereo | Yes |
| Bit rate across files | The same bit rate for every file | Yes |
| Sound | Consistent throughout | Partly, by comparing levels |
| Opening and closing credits | Separate tracks | No, a production decision |
| Retail sample | 1 to 5 minutes | Length only |
| One chapter per file | Required | No |
| Chapter announcement | Each chapter starts with its title | No |
| Plosives, clicks, mouth noise | Free of them | No, editing |
Values are from the Author’s Republic help center and blog linked above, checked on 17 October 2026. A separate Author’s Republic article on chapter tracks says chapters longer than 79 minutes should be split into parts. Check both pages before a release, because a distributor can change its list.
After upload, Author’s Republic shows an Audio Track Validation Report for your files, per the same help center. Checking before upload means that report should be a formality.
How is this different from ACX?
The core numbers match. As our ACX audiobook requirements check page sets out, ACX also asks for -23 to -18 dB RMS, peaks no higher than -3 dB, a noise floor at or below -60 dB RMS, and 192 kbps CBR MP3 at 44.1 kHz. The differences are at the edges: Author’s Republic adds a 170 MB file size limit and a 119-minute file length, and its blog post describes the head and tail as silence, where ACX asks for room tone. Many narrators prepare one master that meets both, but compare the two lists line by line before you assume it.
Which items can a batch tool check, and which need your ears?
The top block of the table is numbers. A meter can measure every one of them, and software can correct most of them: RMS by gain, peaks by limiting, sample rate by resampling, format and bit rate by encoding.
The bottom block is content. No meter knows whether a chapter starts with its title, whether the credits are separate files, or whether a click at 14:32 is a page turn. Plan a listening pass for those and keep the measurable checks automatic, so your listening time goes to performance and edits rather than reading meters.
How do I check a whole audiobook with WavSpec?
WavSpec ships ten built-in delivery specs, each cited to its source document, and one of them is the Author’s Republic audiobook preset. For voice specs it measures whole-file RMS, sample peak, noise floor and head and tail room tone, alongside integrated loudness and 4x oversampled true peak.
- Export your edited chapters. Keep a lossless master per chapter, such as 24-bit WAV, so the MP3 is encoded once, at the end.
- Add the folder. Drag the chapter folder into WavSpec, or use Add folder (Ctrl+Shift+O).
- Pick the preset. Choose Author’s Republic audiobook as the client specification and set a delivery folder.
- Check first. WavSpec measures every chapter and shows pass, fail or advisory for each criterion, so you can see which chapters are quiet, which have peaks over the ceiling, and which have a noisy floor.
- Correct. One run sets gain to the RMS target, limits peaks only where the gain pushed them over, resamples to the delivery rate, handles head and tail room tone, encodes constant bit rate MP3 through the Windows encoder, and gives the delivered copies plain file names.
- Read the report. The PDF, HTML, CSV and JSON report lists before and after values per criterion, a timeline per chapter, a consistency line across the book, and the SHA-256 of every delivered file.
Your source files are opened read-only and never overwritten. Delivered files go only to the folder you choose.
Run your next book through the Author’s Republic preset during the 15-day free trial.
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What can WavSpec not fix?
Be clear about the limits before you rely on any tool:
- Noise. If a chapter fails the noise floor, WavSpec reports it. It does not remove noise, and raising RMS raises the floor with it. Fix room noise at the recording or with a restoration tool, then check again.
- Plosives, clicks and mouth noise. These are editing work in your DAW.
- Long chapters. WavSpec does not split a 130-minute chapter into parts. Do that in your editor at a natural break.
- Credits and sample. WavSpec checks files you give it; making the opening credits, closing credits and retail sample files is up to you.
- Silence versus room tone. WavSpec pads or trims head and tail room tone using the chapter’s own room tone and replaces digital silence. Author’s Republic’s blog describes the head and tail as silence. Read the preset’s criteria in the spec editor, and if your distributor wants something different, duplicate the preset and adjust it.
Where a distributor’s own instructions show a free tool, such as the Audacity steps in the Author’s Republic help center, that route works for a chapter at a time. A batch tool earns its place when you have thirty chapters and want them consistent.
Why do chapters fail RMS when they sound fine?
RMS is an average, so a quiet narrator with a few loud lines can sit below -23 dB RMS while sounding normal on headphones. Raising the whole chapter by gain to reach the RMS window can push the loud lines past -3 dB, which is why gain and peak limiting have to be done together and in the right order. Our post on fixing true-peak overs in WAV files explains the order.
A noisy room makes it worse: raising gain to meet RMS raises the floor too, and a chapter can pass RMS and fail the noise floor in the same step. That is why checking all three numbers together matters more than meeting any one of them.
Frequently asked questions
Does WavSpec have an Author’s Republic preset?
Yes. Author’s Republic audiobook is one of WavSpec’s ten built-in specs, alongside ACX audiobook (Audible), EBU R 128, ATSC A/85, Apple Podcasts and others. Each preset is cited to its source document.
Can I use the same files for ACX and Author’s Republic?
Often, but check. The loudness and peak numbers match, but the edges differ, including file size, maximum length, and how the head and tail are described. WavSpec lets you run the same chapters against both presets and compare the reports.
Does WavSpec change my original recordings?
No. Originals are opened read-only. Corrected copies and the report go to a separate delivery folder.
Does the audio leave my PC?
No. WavSpec has no account, no telemetry and opens no network connection.
Which Windows version do I need?
Windows 11 version 22H2 or later on an x64 PC.
Try WavSpec
WavSpec is a one-time purchase in the Microsoft Store, with a 15-day free trial. Run a finished book against the Author’s Republic preset and read the report before you upload. For more on audio delivery, see our audio delivery QC checklist or the WavSpec product page.
Upload chapters that already meet the numbers.
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Author’s Republic is a trademark of its owner. ACX and Audible are trademarks of Audible, Inc. or its affiliates. Microsoft and Windows are trademarks of the Microsoft group of companies. WavSpec is not affiliated with or endorsed by any of them.
Last updated 17 October 2026. Published by Automata Labs, a software company in Canada.