Noise

Noise, in short, is a random signal. It is most often identified as a sound that does not have a distinct pitch, such as hissing, breath noise, or the sound of wind or the surf. It can also be a slow moving control signal that replaces a low frequency oscillator but which is random rather than periodic and predictable in nature. Noise is often described by different “colors” such as white, pink, red, or blue which have different frequency distributions.

When creating sounds on your synth, noise can be an important element in creating percussive sounds or adding human breathiness to pitched sounds.

Noise can also be thought electronically as a series of random numbers or voltages that you can sample (freeze in time) to produce random voltage outputs – this is why noise is often used as an input to a sample and hold module.

Noise is also often associated with an unwanted sound or randomness introduced into a signal – such as hiss being added by a filter, or random glitches introduced by unwanted signals being introduced into the power supply or control voltage lines of a module.