Accessible Audiobook Production: General Recording Notes

Suggested Prerequisites

Before reading this, you might want to read:

• Introduction to Accessible Audiobook Production
• Accessible Audiobook Production: Audiobook Formats
• Accessible Audiobook Production: Files and Labeling
• Accessible Audiobook Production: What to Record

Technical Choices for Audiobook Recording

There are almost endless variables and options when it comes to making technical choices for recordings. The recommendations in this document might be useful as a guideline for some publishers, but there is lots of room for developing your own in-house approaches. 

Audio Notes

Some of the following information may already be well known to your audiobook producer. Nevertheless, if you are just starting out, it may be helpful to know!

• Volume/level consistency is integral to guarding the safety of readers’ ears as well as avoiding level fluctuations that interrupt the reading process. The volume should remain consistent from chapter to chapter as well as from audiobook to audiobook.
• Hums, hissing, buzzing etc. are straining to the ears and nervous system, especially over long periods of time (i.e. the length of a book). Use optimum recording techniques and equipment to avoid hissing and distortion.
• Aim for a vocal tone that is warm and crisp. Warm tones are easier on the ears long-term and crispness brings clarity. Room tone and vocal tone should remain consistent throughout the recording.
• Noises outside of the text can be very distracting for a reader and should be avoided, or if necessary edited out. Narrators should work in a place that is isolated from outside noises such as children playing, air conditioners running, etc. Narrators should also consider their own production of noise; physical adjustments in their chair, touching the microphone or stand, a lot of mouth noise from being dehydrated or having a cold, etc.

Specific Audio Requirements

These are the audio requirements that NNELS uses – some of these may be useful as a guideline:

• Include 1 second of room-tone at the beginning of every section and 3 seconds of room-tone at the end.
• Room-tone: Noise floor is at -60db maximum, i.e. close to silence.
• Level: Your recording should measure between -23db and -18db RMS (average) with peak values no higher than -3db.
• File type: If the audiobook is using stereo effects it should be exported as balanced stereo MP3s at 128-192 kbps. If the audiobook is only voice with no effects it should be exported as mono MP3s at 64-96 kbps.

A Note on File Size

Many commercial audiobooks are recorded at 320Kbps which is very high for a single vocal. We recommend 128-192Kbps for books with stereo effects, and 64-96 kbps for audio with no effects. This results in high quality audio with faster download times and smaller storage.

This is an important accessibility factor, as people that rely on audio for information may not have the storage for so much data, or the time/internet connections for long downloads. Keeping the file size low increases the accessibility of the file, without much compromise to the audio.