Layering of Sound – What tool to use?

The original tools – looking at the old time radio show production:


Sound effects – machines to emulate sounds – for example the sound of a motor was created with a fan flapping on a tin tub. A simple bucket with dishes and flatware to create the sound of doing dishes. Recordings of chicken noises, etc. played back on a record player.

Microphones – to capture voice, sound effects. Different types of microphones to create different perspectives.

Voice – microphone to subject distance to create a change in spatial perspective, with direct sound heard less or more compared to reflections.

Mixing board – accepts the electric signals from microphones and the record player. Three microphones (main voice mic, telephone mic, and the sfx mic) and the record player to make four sources of electric current fed into the mixer. This would mean the mixer needed at least four inputs.

At each input what can you do? You can increase the current (gain) to increase the amplitude or decrease. Affect frequency, selectively increasing/decreasing the gain at specific frequencies. The electric currents are then combined into a single electric current which can then be sent over the airwaves.

This process is still widely used for live event presentation of sound – concerts, plays, etc.

How do we do this on a computer based digital audio mixer (we’re going to use Audacity)?


Sound files – Sample Rate, Bit Rate, format (compressed/uncompressed), 1CH, 2CH, 4CH. Sound effects, voice, music, etc. all have to be sound files.

Inputs become tracks. Tracks can be mono or stereo.

Gain – to affect the level of each track

Pan – push the track signal to the L channel or the R channel

Filters – Frequency filters (High, Mid, Low) or complex filters that combine changes to frequency and amplitude over time (reverb filter, compressor, etc.)

Transposing changes to Gain, Pan, and/or Filter settings over time. This is usually how you create perspective.