EQ (Equlization) lets us boost or cut selected frequencies within a sound to change the tone of that sound. What we hear is a composite waveform of the fundamental (frequency we hear as a note) and higher frequencies called harmonics or overtones that create the tone or timbre of a sound. That is why a note played on a piano, for example, sounds different than the same note sung by a person. Sometimes we say “filter” instead of “EQ” because we can filter some frequencies out for creative or practical reasons. For example:
- If bass is too strong and makes everything sound muddy, one can turn down low frequencies.
- If the vocals are hard to hear, one can boost the mid frequencies.
- If a sound is too crisp or hissy, we can reduce high frequencies.
Examples:
Dry vocals:
The same recording with high frequencies cut, notice how it sounds like the performer is in a different room:
The same recording with middle frequencies boosted, like old radio broadcasts:
Filters can also be automated, like the examples below:
Clean guitar:
The same recording, with an automated sweep filter added:
