I am recording my first audiobook for ACX and having a bit of trouble getting my set up to meet standards. I’ve attached a 15 second unedited WAV file with a couple seconds of silence at the beginning. I’m recording on an Audio Technica AT2020 mic and Focusrite Scarlett 2i2. When using the following chain from the Audacity AudioBook Mastering page,
Effect > Equalization > Select Curve: Low roll-off for speech, Length
of Filter: about 5000 > OK.
Effect > RMS Normalize: Target RMS Level -20dB > OK.
Effect > Limiter: Soft Limit, 0, 0, -3.5dB, 10, No > OK.
I am able to pass the ACX check plugin on Audacity. However there is a very audible hissing sound. I can remove this with Noise Reduction, but it takes a couple of times, and I worry that that will cause an ‘over processing’ fail with QA. In the raw, unedited WAV I’ve attached, I am failing to meet requirements due to RMS level as it is very low. The problem is, when I raise the input, I fail Noise Floor. I am afraid this may be due to sounds coming from the mic itself, but I really am not sure to be honest. Any suggestions would be greatly appreciated. Thank you!
That voice signal it too low : its RMS volume is only about -40dB.
You should be aiming for -20dB RMS volume, before any processing in Audacity.
If you can turn the gain up on your hardware, that will make the voice-signal louder,
and could improve the signal-to-noise ratio, i.e. make the hiss-level lower relative to the voice-signal.
Check if your microphone needs (48v) phantom-power to be supplied to operate correctly …
Mastering 4 will always satisfy Peak and RMS. If you massively fail Noise, then you need to go back and sort what happened to the original performance.
There is always a little microphone noise drifting through any performance (ffffff). It’s your job to make your voice loud enough so nobody notices the noise or, more importantly, the noise passes the ACX specification. The English translation of -60dB is a noise level a thousand times quieter than your voice. It’s pretty stiff.
You should be about a Hawaiian Shaka away from the microphone…
…slightly less if you’re using a pop filter…
Glance over to the Audacity blue waves and bouncing sound meter. The meter should occasionally pop up to about -10db to -6dB and the blue wave tips up to about halfway.
Your sample blue waves are almost flat line. If you are about the right distance from the microphone, then boost the volume at the interface. It’s not unusual to have the adjustment all the way up. Home recording microphone systems are designed to work at “restrained” volume. Slightly low volume is usually OK.
Overload is immediately fatal with permanent sound damage. The Audacity meter goes all the way up and turns red. The blue waves fill the track top to bottom.
The interface knobs turn green and red to indicate volume level.
There’s one other thing you can do wrong. If you are using one channel of the two-channel interface, you might record in stereo (two blue waves) with one wave your voice and the other dead flat line. The mistake is to mix down to mono which will reduce the volume of your voice by half. Instead, use the menu on the left under the black arrow and Split Stereo To Mono. Delete the one silent track.
Hey thank you!! This is really helpful info. I hadn’t read anything before about splitting Stereo To Mono and deleting the silent track. I will apply all these things you mentioned. Thanks again!
