How To Use A Vocal Mic
Everyone thinks they know a priori how to use a microphone (more commonly called, a “mic”). The reality is that like any other tool, one must learn to use a mic. While every individual’s voice and singing style are different, and so everyone’s use of a mic should slightly differ, there are some general principles and guidelines that apply to everyone.
The physics of sound and electricity govern a mic’s general principle of operation: a mic takes sound and translates it into an electrical signal; loud sounds generate a large signal and soft sounds create a small electrical signal. This translation process is always imperfect, and so many different types of mics have been invented to allow different mics to be chosen for different circumstances (i.e., balancing the trade-offs between how particular mics translate sound and the sound being captured by the mic).
A mic is only able to capture sound that exists (i.e., it records what it hears):
Just as buying an expensive, high quality piano cannot improve your sight-reading ability, so buying a high quality mic will not make a bad voice sound great. Just as a well trained and practiced pianist will play better and sound better on a well made instrument, the right mic, properly used, will capture the most desirable qualities of a voice, producing a much better result than would be achieved with the wrong mic.
All the above has been written to underscore the importance of proper singing and speaking technique: garbage in, garbage out applies to mics, just as it applies to computer data.
Every mic as a “pick up pattern.” This is the area around the mic in which sound will be heard by the mic. Some mics have a focussed pattern and are said to be “directional”, and other mics are not focussed and are said to be “omnidirectional”.
|Figure 1—Example of a directional mic where the pick up pattern is said to be “cardioid” (this image is from the Shure SM-58 data sheet).||
Sound travels in specific directions; it is not omnipresent. These two principles—that mics are directional and that sound travels in specific directions—guide how we use a mic.
When you sing or speak, sound emanates from your mouth perpendicular to your lips, face, and teeth. Thus, you need to orient your face so that your voice is directed toward/into the pickup-pattern of the mic.
A mic picks up all sounds equally; that is, it doesn’t capture your voice better than the person or piano placed next to you simply because you are the mic’s owner. Thus, your voice must be loud enough that your voice stands out over the other sounds/noises, compared to the other sounds in the mic’s vicinity. This means that in a live singing situation, with floor monitors on stage, you must be very close to the mic to ensure your voice is louder than the sound coming from the monitor.
The following are general do's and don’ts regarding the use of mics:
One last note regarding lapel mics (sometimes called lavalier mics): when sound emerges from your mouth, there is a “sound shadow” onto your chest cast by your chin. This means that a lapel mic should not be attached directly under the chin of the person’s shirt. The mic should be attached several inches below the neck of the person speaking so as to avoid the chin’s sound shadow. A related usage note is to ensure that a lapel mic does not become covered by a piece of the wearer's clothing: anything that obscures the mic will reduce its ability to “hear”.