Getting Good Quality Voice Audio

Date:    Fri, 14 Nov 1997 10:34:40 GMT+10
From:    Deri Hadler <dhadler@CSU.edu.au>
Subject: Re: Voiceovers without a studio

>Does anyone have a recommended process for recording medium-quality
>voice overs directly to the Mac? I'm building a kiosk and I don't really
>have the time or desire to get involoved with a studio. It doesn't have
>to be super high quality. 

All the comments have been technical. The key to GOOD voice over is the environment, the room you record it in.

1. Don't record in the same room as your computer. Your Mac makes all sorts of whirring noises that you have become used to. If these get recorded at along with your VO you probably won't notice because you have tuned them out and the noise in the room will mask the similar noise on the recording. The key is quietness. Even small extraneous noises will become distracting when it is replayed in a different context. BTW don't be fooled by claims that a directional microphone will exclude extraneous noise. In some cases the extra sensitivity on the axis makes extraneous noise worse. What ever mic you use the room has to be quiet.

2. There is a theory that a recording booth must be damped down with heavy drapes and acoutic foam so it is DEAD. This is almost impossible to achieve and undesirable anyway. Most booths are small and square and exhibit standing wave boosting a lowish frequencies. A room with one 2 metre (6 - 7 ft) dimension starts getting a boost at around 160Hz. To effect any dampng at that frequency you would need an absorber at least half a metre (18 - 20 inches) deep. ( All figures are approx, VERY approx). Heavy drapes will affect the higher frequencies leaving you with a room that's just boomy because the highs have been damped more than the lows. Some people like the deep rich sounds of this artificial bass boost however it seldom sounds good once it gets into your users enviroment. Turning down the bass control on your mixer EQ reduces the bass but doesn't reduce the boomy, resonant atifacts that the standing waves produced. I find that any medium sized room with carpet, non-glossy paint and lots of bumpy bits (like shelves, soft chairs etc) can be made to sound better than highly damped environments.

3. Get close. Whatever microphone you use, work close to it. The closer you are to the mic, the louder the relative voice level will be, the lower input gain required and therefore less extraneous noise/room acoustics will be picked up.

   There are two problems with this. Working close to a mic can induce breath popping where the rush of air from the mouth overloads the mic diaphragm and produces a thump. This is most obvious on cussive sounds like P, D, K and T. Place you hand about 100mls (4 inches) in-front of, and just below your mouth and recite the alphabet, you will see what I mean. Now do the same with your hand slightly above your mouth. You can reduce popping a great deal by working below the microphone rather than over it or directly into it. Use a stocking and a wire coathanger to make up a simple pop filter (just like you see on video clips) and place this between the mouth and the mic.

   Secondly, Working close to a uni-directional mic will produce an artificial bass boost called proximity effect. Again, while it may sound great through high-quality monitors it may not be suitable for small speakers. I use it a lot in my band to get a full resonant smokey jazz sound, but I don't do it all the time. Some mics have a bass cut switch specifically to compensate or you can reduce the bass on your mixer. Most rock mics, like the Shure SM58, are uni-directional and get some bass boost up close. Personally I use an omni-directional mic which doesn't suffer from proximity.

Deri Hadler
Instructional Designer
Open Learning Institute
Charles Sturt University
Wagga Wagga
NSW 2676 Australia