Microphones: critical tools in the recording studio

Microphones are important in the recording world. It is possible though, to produce music without a microphone if synthesizers and computers produce all of the sounds and instruments. In the earliest days of recording, the notion of making a recording without a microphone was exactly that. A notion…a crazy notion. There were no electronic instruments or amplified instruments so a microphone captured every sound.

The earliest microphones could only capture loud sounds, which is why early-recorded music is brass band music such as Souza marches. If there were a subtly nuanced flute part in an orchestral work, the part would not make it on the recording. Loud speakers (not those speakers) had to shout into the microphones for their voices to carry to an audience. Microphone design and sensitivity did progress though, and today’s least expensive condenser microphone will have frequency responses from 20 Hz to 20kHz which is more than most human ears can hear at their peak. As people age their hearing drops off and they lose ability to hear higher frequencies. Engineers train and protect their hearing so they can hear as much as the microphone can produce within human limitations.

A microphone picks up sound pressure differences caused by sound waves. Inside the microphone is a diaphragm made out of a very thin Mylar material that is like the thinnest plastic. When a person speaks, a string vibrates, or air comes out of a trumpet, the pressure moves the diaphragm and the movement is turned into electrical energy that is amplified into sound. Holding a hand in front of your mouth and speaking allows you to feel the air pressure. The diaphragm is extremely thin and sensitive so it moves at every seemingly undetectable change in air and sound waves. They are so sensitive, in fact, that engineers choose microphones by the amount of ‘air’ they can detect in a room.

Three types of microphones that engineers use are: dynamic, condenser, and ribbon microphones. Each has its own specific purpose and characteristics, and within each type are myriad qualities engineers utilize. Each microphone is different and different on each source. For example, a microphone that is excellent for capturing an acoustic guitar may not be suitable for a vocal recording. The choices are entirely subjective as well. One engineer may use a certain microphone for vocal recording and another engineer would not use that specific microphone as a doorstop. Interesting when one considers that many classic recordings used only one or two microphones with musicians and singers gathered in a circle around the microphone.

The next articles will look more in-depth at each type of microphone and some of the technical aspects of each. There will be information on polar patterns, frequency response, power usage etc. First up are the dynamic microphones and the uses and qualities that make them live-application workhorses. Until the next installment, pay attention and listen well!