Now we get to the part of being an audiobook narrator that isn’t quite so much fun. It’s a good news / bad news situation. It’s called Post Processing and it means that you’re responsible to be the producer of the final audio file. In the previous steps, you’ve read the book and listened to what you’ve read to make sure that there aren’t any mistakes in the reading. In this stage, you’ll be doing the steps which make the audio files acceptable to publishing platforms like Audible, Amazon, iTunes & Findawayvoices. These steps are:
- Noise reduction – Unless you work in or have a totally sound proof recording studio – which most of us don’t – there will be some background noise that your microphone will pick up. You eliminate this noise with your DAW software by being silent for the first 5-7 seconds of a track, then “defining” that as “silence” for your software. The software will then take out that level of sound.
- RMS Normalizing – RMS (Root Mean Square). Assuming you’re not a mathematician, “the easiest way to understand RMS is simply it’s just a unique way of finding out the ‘average’. …Technically RMS is used to characterize the ‘average’ of continuous varying signals such as audio, electrical signals, sound etc.” https://www.audiorecording.me/understanding-what-does-rms-stands-for-in-audio-definition-details.html. The standard for most publishers is RMS measuring between -23db and -18db.
- Graphic Equalization – “Equalizers are commonly used by audio engineers…to adjust the frequency response of audio….They are essentially a group of filters designed to provide a custom overall frequency response.” https://www.mathworks.com/help/audio/ug/graphic-equalization.html. Simply put, it makes your recording sound better. Every narrator sets their own graphic equalizer to fit their own voice and what they think sounds best.
- Compression – Compressors and limiters are used to reduce dynamic range – The span between the softest and lowest sounds. Using compression can make your tracks sound more polished by controlling maximum levels and maintaining higher average loudness. https://www.uaudio.com/blog/audio-compression-basics/
- Normalizing – Audio normalization is a process that increases the level of a recording by a constant amount so that it reaches a target – or norm. Normalization applies the same level increase to the entire duration of an audio file. https://blog.landr.com/audio-normalization/ Most publishing platforms call for -3db peak value and a maximum -60db noise floor.
- De-Clicking – “Recording vocals in a quiet studio environment is a delicate process, as microphones tend to pick up every little detail of the human voice. Things that we don’t hear when we’re in conversation with another person are magnified and can become uncomfortable to listen to…i.e. lip smacking, saliva cracking, mouth clicking. In the process of recording, you might not notice these sounds. The trouble is, they often reveal themselves when listening back and treating (processing) the audio files afterwards” https://blog.accusonus.com/audio-clean-up/how-to-stop-mouth-noises/ Your DAW software may provide a “De-clicker” or you may have to get / construct a macro to do the job. Either way it’s necessary. Unfortunately, no software can tell the difference between a mouth click (which you don’t want) and a word ending in a hard consonant sound (such as “test”). A software de-clicker will help, but it won’t do the entire job AND sometimes it erases a sound you didn’t want erased. Always make a copy of your original sound track so you can “re-insert” sounds that the software incorrectly took out.
- De-Essing – “De-Essing is the process of attenuating or reducing sibilance (a figure of speech in which a hissing sound is created within a group of words through the repetition of “s” sounds), or harsh high-frequency sounds that come from dialogue or vocals using the letter S, F, X, SH, and soft Cs.” https://www.izotope.com/en/learn/the-dos-and-donts-of-de-essing.html This is handled by your DAW software in a manner similar to de-clicking, with the same warnings and pitfalls that you find in de-clicking.
- Noise reduction – The processes listed above will re-introduce sounds where no sound was heard before. Always remember that the microphone hears everything, even if you don’t. At this stage you may want to run a noise reduction process to further prepare your tracks for the next step. It will depend on what you want to do and how your voice interfaces with your DAW software and equipment.
That’s the bad news. The good news is that you can, fairly easily, build a macro in your DAW software to run these steps as an unattended process, being mindful that it can easily take hours of processing, depending on how many tracks you process at one time. I have two computers in my studio set up. I can set one computer to run the post processing and use the other to record new material.
Next comes part 4 – Visually editing out breath sounds and mouth clicks.
#DrWhodunit #audiobooknarration #audiopostprocessing #audiocompression #RMSnormalizing #audiodeclicking #audiodeessing #audionormalizing #audiocompression #audionoisereduction