Fun With Audio, Part 2

Ok! Today we have the 2nd part of the audio post. This is the after recording part, which has been the more difficult end of the deal.

A whole lot of information about mastering audio lives on the internet. There are so many ways to get where you’re trying to go, and each one is more technical than the last. It gets confusing for someone who’s never studied this stuff in an academic environment. Determining which bits I really needed was about 70% of the battle.

ACX has the following requirements:

Be a 192 kbps or higher MP3, constant bit rate (CBR) at 44.1 kHz
Contain only one chapter/section that is shorter than 120 minutes
Section header must be read aloud
Have room tone at the head and at the tail
Be free of extraneous sounds
Measure between -23dB and -18dB RMS
Have-3dB peak values
Have a maximum -60dB noise floor

Right. The first 5 things were no trouble. Those last 3 bits? They were the bane of many an evening for me.

I watched YouTube videos, scoured message boards, the ACX site, the Audacity website (open source software that I use to record and edit), various other sources. I learned about audio software plug-ins, compressors, soundwaves, and a whole bunch of other stuff that I never would’ve guessed I might need to know at some point. I spent many hours experimenting with the software and different mixes of settings, trying to reach these magical numbers. I finally got it.

This is what works for my voice and my setup.

Audacity plug-ins: These have been an essential part of my process. If I lost them, I’d have to find an entirely new mastering process, and I would cry. These do not come with Audacity. They’re separate downloads.

High Pass Filter
RMS normalize
ACX check (quality control)

A word about the ACX check. Many moons ago, I thought I had a file that might pass inspection. I submitted a sample. A man replied, and said I did not meet the requirements and referred me to another plug-in called wavestats. This was incorrect information. The fact that I took his word for it gives me angry feelings. He set me back by a very long time.

ACX check is fine. ACX check works.

A mastering chain is a set of steps followed to being a raw audio file up to spec. Mine looks like this:

High Pass Filter set to Frequency: 250, Roll-off: 6dB
RMS Normalize to -18
Limiter to soft limit, -5.5dB, Hold 10
Noise Reduction: Noise Reduction: 12dB, Sensitivity: 6.0, Frequency Smoothing Bands: 3

This is a very important part of the production process, but unfortunately, it’s not the only thing needed to get an audiobook in order. Professional audiobook production runs about $100-350 per finished hour.

Sound fun, right? On the surface, that money looks tempting as heck. The key word in that sentence is “finished”. Alas, a finished hour of audio is not an hour of labor. When I first started, a finished hour of audio was taking me about 10 hours, by my estimate.

This is what’s involved: recording, cutting the raw audio, re-recording any bits where I screwed up or the mic cut out and patching those in, listening to the file to make sure it’s right, applying the mastering chain. There are smaller pieces in there, of course. Audiobook production is expensive for a reason.

Needless to say, I have a full appreciation for the process. It’s grueling work, a whole bunch of sitting in front of the computer with my voice prattling on in my ears. This is not an activity for the lazy.

I plan to send many audiobooks into the world because, for whatever weird reason, I actually like all this nonsense.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s