The amount of cycles per second (cps) created by a sound wave is commonly referred to as the frequency.
If you are a musician, you may have tuned your instrument to A/440. Here, “440” is the frequency of a sound wave.
Unlike amplitude, which is measured in decibels, frequency is measured in hertz (Hz), named after the German physicist, Heinrich Hertz.
The average human hearing range is from 20 to 20,000 Hz.
Typically, once 1000 cycles per second is reached, the frequency is referred
in kilohertz (kHz), i.e., 1000 Hz = 1 kHz, 2000 Hz = 2 kHz, and 3000 Hz = 3 kHz.
Frequency is related to the pitch of a sound. Here is a handy chart to help
identify the frequency ranges of various instruments and how the keys of a piano relate to frequency.
The first note on a piano is A, which is 27.5 Hz. Have you ever turned up
the bass or treble on your car stereo? If so, you are boosting or cutting the amplitude of a frequency or range of frequencies.
This is known as equalization (EQ), a vital aspect of audio production.
Each frequency range has distinct characteristics, and some common terms can help you to identify them. I will go into further detail throughout
the book, but let’s start here:Frequency is often divided into three ranges:
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Low or bass frequencies are generally between 20 and 200 Hz. These frequencies are omnidirectional, provide power, make things sound bigger,
and can be destructive if too much is present in a mix.Mid, or midrange,
frequencies are generally between 200 Hz and 5 kHz. This is the range within which we hear the best.
These frequencies are more directional than bass frequencies and can make a sound appear “in your face,” or add attack and edge. Less midrange can sound mellow, dark, or distant.
Too much exposure can cause ear fatigue.High or treble frequencies are
generally between 5 and 20 kHz and are extremely directional. Boosting
in this range makes sounds airy, bright, shiny, or thinner.
This range contains the weakest energy of all the frequency ranges.
High frequencies can add presence to a sound without the added ear fatigue.
A lack of high frequencies will result in a darker, more distant,
and possibly muddy mix or sound.Midrange
is the most heavily represented frequency range in music.
It is often broken down into three additional areas: Low-mids, from around
200 to 700 Hz darker, hollow tones Mid-mids, from 700 to 2 kHz more
aggressive “live” tones High-mids or upper-mids, from 2 to 5 kHz brighter, present tones