In general, bass and drums are the cornerstone of a musical theme in a band. Then guitars, keyboards and other instruments complement the harmonic setting of the musical arrangement. Finally, on top of all this, vocals are the crown jewel of the song.
I’d like to direct focus to a not-much-discussed subject: vocal mixing. The approach of the subject matter in this article is toward live events such as concerts, houses of worship, or any other event where one or more singers are performing.
The Source: A Human Voice
The human voice is one of the most—if not the most—common sources of sound. It has a wide frequency range (75 Hz—8 kHz, including harmonics), comparable to that of the piano. The human voice also has a wide dynamic range covering an astonishing 80 dB (40—120 dB).
You can expect a lot of variability and stability issues. A sung melody can contain a sample of the entire dynamic range just in a single verse, an example of how much its intensity can vary.
Another attribute of the voice is its timbre or tonal color. This distinguishes one instrument from another, a guitar from a banjo, or a violin from a flute. Now, in many cases it’s quite difficult to distinguish one electric guitar from another, but the timbre of human voices distinguishes one singer from another singer.
Capturing The Vocal Source
To capture and reinforce vocals for live performances, the most foolproof technique is close miking. You need to have, at the least, an idea of how the vocals sound (refer to my previous paragraph), as well as the microphone handling technique of the singer(s), in order to make a good decision on what mic(s) to choose from (assuming you have this luxury). Know your mics—know their characteristics, the types, the polar patterns, the strengths and weaknesses.
Some voices may take advantage of the proximity effect that certain mics provide to accentuate the low end of a weak voice, but sometimes a mic with a more open polar pattern is necessary in order to be able to capture an exited jumping singer. Using a single mic for two singers at the same time generally isn’t a good idea unless you’re it’s right mic, and in the right ambient setting.
And in general for live applications, the tighter the polar pattern, the better and cleaner the vocal pick-up will be. It’s advisable to use mics with a directional pattern as opposed to an onmidirectional pattern.
Another tactic that can help is to train vocalists on the proper use/handling of mics as well as the various types. They should understand basic mic properties and polar patterns—this knowledge can help them do a better job.