There are different types of sound mixing all concerned with the mixing or combining of various audio signals from a number of different sources and blending them into one cohesive mix or listenable output.
Types of Audio Mixing
The various forms of audio mixing range from:
- Live music mixing
- Studio or recorded music mixing
- TV, Audio Visual and other sound to picture mixing
- Live Sound Mixing; live programmes for both TV and Radio.
- Recording and Mixing for Radio; including commercials, features and programmes.
These various types of audio all have their own demands and the mixes for each may be considerably different.
Mixing for any audio output on radio the audio engineer has to consider the vagrancies of the medium and take notice of the various forms of radio transmission which is the eventual vehicle for the audio and the way the intended audience hears it. Mixing for a live audience is an entirely different job from mixing recorded speech, or a music radio programme. All the different receivers the audience choose to listen on can vary too, from FM to DAB transmission, podcasting to satellite radio transmission and each has its own separate characteristics.
The Sources of Audio Signals.
While much of radio’s output is live broadcasting of recorded music and voice over, many might feel there is not a lot of mixing to be done. But consider the simple mixing of music and voice over, inserts and cues, stings links, and commercials, apparent in a lot of music radio programmes still contains a mix of elements that have to be in the right proportions for the listener, or it just won’t ‘sound right.’
There is still a considerable amount to consider and to mix together well. The main sources of audio signals for most radio broadcasting both ‘live’ and recorded can be broken down into the following elements:
- Voice Over (s). (vo) Both the main presenter, joint presenter, contributors and guests
- Sound Effects (sfx) : sources can be pre-recorded effects or sometimes live effects, like background noise. Radio sound effects in early broadcasting were often added live
- Music: input ranges from featured songs, background music, music beds, stings, links and jingles
- Ambience: good sound engineers may record some additional ambience for recorded pieces to enable more control over this, but live recording has to obviously consider this carefully.
There is a major element of personal taste and experience in choosing how to mix these elements together and one person’s mix may be another person’s cacophony but in the final mixes of all them, each of the elements should be able to be heard in the appropriate places. To achieve this all the sources are ‘mixed down’ using a mixing console, or a personal computer that offers a similar facility.
The Mixing Process
A mixing console will enable all the audio signals to be mixed down together into 2 tracks (stereo) or one (mono) or increasingly but less so for radio, multi tracks for surround sound offering a 360 degree effect. The console is usually a series of faders (or simple sliding volume controls) but it also offers and can add so much more to the final broadcast or recording. Even with simple mixing of voice or speech, music and effects for radio the sound engineer may consider adding some extras by employing some of the following:
- Routing: taking some of signal and directing it to other parts of the desk, or outboard equipment. (equipment outside the desk), and working separately on that signal.
- Processing: configuring or working electronically on the signal and altering it some way, or adding effects to it or the mix.
- Effects: there is a considerable if not unending array of processors and sound enhancers, reverbs and delays, compressors and equalisers, stereo panning and gating, even morphing available to the engineer.
- On-Board and Outboard: many mixers now offer effects built in, or the engineer can add-on a never ending supply of additions as they see fit.
The Final Mix
With so many audio signals to manage, and so many variable add-ons applicable it’s easy to see why, what the good sound or mixing engineer needs most, as well as a good understanding of how the final mix will sound broadcast on radio where it is subject to further processing, is a good pair of ears.
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