If you’re looking to produce an audiobook that meets ACX and/or Findaway Voices technical standards, for free, Audacity is the tool for you.
What you’ll need
- Install Audacity
- Install Acx-check
- Install rms-normalize [If you have Audacity 2.4.1 and later, you won’t need this. Audacity 2.4.1 has a built-in RMS tool called Loudness Normalization.]
For a detailed guide, check out the following resource: Audiobook Mastering
General process
- Import the audio file
- Apply noise reduction
- Apply rms normalize/loudness normalization
- Apply limiter
- Trim anything you don’t want
- Apply Acx-check
Import the audio file
From the main menu, select File > Open. Choose the audio file you would like to import.
Project rate (Hz)
In the bottom left, confirm the project rate (Hz) is 44100.
Noise reduction
Left-click and drag an area of the file with unwanted noise. From the main menu, click Effect > Noise Reduction.
You may need to experiment with the default settings for Noise reduction, Sensitivity and Frequency smoothing. I have had good success with the settings below. Once you’ve adjusted these settings, click Get Noise Profile.
Select the entire audio file by using Ctrl + A. With the audio file selected, click Effect > Noise Reduction. Select OK.
Apply loudness normalization (or rms normalize)
Using Ctrl + A to select the audio, click Effect > Loudness Normalization. In older versions, it’s Effect > RMS Normalize. Set the RMS level to anywhere from -18.00 to -23.00.
Old
New
Apply limiter
The Limit to (dB), or peak value, should be set below -3dB.
Trim
Highlight the audio you want to get rid of using the selection tool. Next, hit the ‘Delete’ key on your keyboard.
Note: Keep in mind that each individual audio file must have between 0.5 and 1 second of silence at the beginning and between 1 and 5 seconds of silence at the end.
ACX check
Click Analyze > ACX Check. [In older versions of Audacity, use Ctrl + A to select the audio, then click Analyze > ACX Check.]
Submit your audio
You’ll need to submit audio files in FLAC or MP3 format, that meet the following technical criteria:
- A constant bit rate of 192 kbps or higher and a sample rate of 44.1 kHz.
- RMS has to measure between -23dB and -18dB.
- Peak values must be below -3dB.
- The noise floor must be below -60dB.
Art and Audio Requirements for Findaway Voices:
https://my.findawayvoices.com/docs/Technical_Requirements_for_Assets.pdf
ACX Audio Submission Requirements:
https://www.acx.com/help/acx-audio-submission-requirements/201456300