A microphone is a transducer that converts analog sound pressure waves into electrical impulses. We all know, however, that what goes into a microphone is not identical to what comes out. A lot of this can be attributed to frequency response, which can “color” the audio. Understanding frequency response is essential to understanding sound recording.
Every microphone colors to some degree the sound it picks up.
The frequency response of any given microphone affects the color of the audio coming out of it. It not only reveals the difference between a $5 crystal mic and $3,000 condenser studio mic, but it also helps determine the right microphone to use for a given project.
A new white paper produced by Azden, a Japanese company that has specialized in pro audio for over 60 years, tackled the subject of frequency response and tried to explain it to the rest of us. Frequency, the company said, refers to how many cycles a soundwave undergoes in a second. This measurement is called Hertz (Hz).
The range of human hearing generally spans from 20 to 20,000 Hz. The frequency of a soundwave determines its perceived pitch. In general, low frequencies are heard as bass and high frequencies as treble. The audible frequency spectrum can be effectively broken down into segments that are commonly referred to as bass, low mids, mid range, upper mids and highs. This is a rule of thumb breakdown, however, and there are no objective standards for these segments.
Loudness, wrote Azden, is the other factor to consider in frequency response measurements. The issue centers around how much louder or softer a particular frequency is once it passes through a microphone. The whole loudness issue can get confusing.
Loudness is measured in decibels, or dB. There are also different kinds of dB. With microphones, dBV is often used. That is dB with a reference of 1 volt = 0 decibels. For the loudness of sound in air, dB SPL is used. It stands for “sound pressure level.”