# Audio Audiobook ACX Validator Validate an audiobook chapter or full file against ACX/Audible submission requirements: RMS, peak, noise floor, duration, format, and chapters. > Canonical page: https://elysiatools.com/en/tools/audio-audiobook-acx-validator - **Category:** Media - **Keywords:** audiobook, acx, audible, validator, rms, peak, noise floor, chapter, narration, submission ## Overview Checks your audio against the ACX technical requirements: RMS level must be between -23 and -18 dB, peak must not exceed -3 dBTP, noise floor must be at or below -60 dB, sample rate 44.1 kHz, mono or stereo, and the file should have chapter markers for navigation. Reports each check as pass/fail with the measured value and the required range, plus actionable recommendations for any failing criteria. ## Inputs - **Audio File** (file): Select an audiobook chapter or full file - **ACX Standard** (select) ## When to use - Before submitting your audiobook files to ACX, Audible, Findaway Voices, or Google Play Books to prevent rejection. - After mastering your narration tracks to verify that the RMS levels, peak levels, and noise floor meet industry standards. - When troubleshooting audio quality issues or checking if your exported files have correct sample rates and channel configurations. ## How it works - Upload your audiobook chapter or full audio file in a supported audio format. - Select your target distribution standard, such as ACX, Findaway Voices, or Google Play Books. - The validator analyzes the audio file's RMS level, peak amplitude, noise floor, sample rate, and chapter markers. - Review the detailed pass/fail report containing measured values, required ranges, and actionable recommendations for any failed criteria. ## Use cases - Verifying that a newly recorded audiobook chapter meets the -23 to -18 dB RMS range required by Audible. - Checking if a mastered WAV file exceeds the -3 dBTP peak limit before exporting to MP3. - Ensuring a batch of audio files has the correct 44.1 kHz sample rate and mono/stereo configuration for Findaway Voices. ## Frequently asked questions ### What are the standard ACX requirements checked by this tool? It checks for an RMS level between -23 and -18 dB, peak levels not exceeding -3 dBTP, a noise floor at or below -60 dB, and a 44.1 kHz sample rate. ### Can I validate files for platforms other than ACX? Yes, you can select Findaway Voices or Google Play Books standards to validate against their specific requirements. ### What audio file formats are supported? The validator accepts standard audio file formats, including MP3 and WAV. ### Does the validator check for chapter markers? Yes, it verifies whether the audio file contains appropriate chapter markers for navigation. ### What should I do if my file fails the noise floor check? The tool provides actionable recommendations, which typically involve applying noise reduction or adjusting your recording environment. ## Related tools - [Audio Dictation Quality Checker](https://elysiatools.com/en/tools/audio-dictation-quality-checker): Check whether audio is suitable for transcription using SNR, clipping, format, channels, and speech activity. - [Audio Concat Validator](https://elysiatools.com/en/tools/audio-concat-validator): Validate concatenated audio files for errors and inconsistencies - [Audio Duration Checker](https://elysiatools.com/en/tools/audio-duration-checker): Get the exact duration of an audio file - [Audio Platform Delivery Checker](https://elysiatools.com/en/tools/audio-platform-delivery-checker): Check podcast or spoken-audio files against platform delivery profiles, including codec, loudness, metadata, chapters, cover art, and decodability. - [Audio Codec Swap](https://elysiatools.com/en/tools/audio-codec-swap): Change the codec of an audio file within a chosen output format - [Podcast Chapter Marker Builder](https://elysiatools.com/en/tools/podcast-chapter-marker-builder): Build every podcast chapter format from one timecoded list: Podcasting 2.0 JSON + RSS tag, ID3v2.4 CHAP+CTOC burned into an MP3, Vorbis comments, mp4chaps, YouTube timestamps and SRT, with a per-player support matrix. - [Audio Caption Sync Checker](https://elysiatools.com/en/tools/audio-caption-sync-checker): Compare SRT or WebVTT cue timing with likely speech activity and flag timing drift. - [AAC to M4A Converter](https://elysiatools.com/en/tools/aac-to-m4a): Convert AAC audio files to M4A (MPEG-4 Audio) format with quality and channel controls ## Samples - [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio - [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free Raw PCM Audio Samples](https://elysiatools.com/en/samples/pcm-samples): Raw PCM s16le audio samples featuring nature ambience and relaxing music for waveform, playback, and conversion workflows ## Related content - [Audiobook & Voiceover Production Tools](https://elysiatools.com/en/hubs/audiobook-and-voiceover-production-tools): Prepare narration takes, proofread against the manuscript, repair breaths and room tone, choose strong reads, and export ACX-aware audiobook or voiceover segments in your browser.