Brownian noise, also known as Brown noise or red noise, is a type of noise signal characterized by a power spectral density that is inversely proportional to the square of the frequency. This means that it has more energy concentrated in lower frequencies, resulting in a deep, rumbling sound that is smoother than white noise.
In synthesis, Brownian noise can be used as a sound source or as a modulation signal for various purposes, such as:
- Sound design: Brownian noise can be used as a sound source to create deep, rumbling textures, simulate natural sounds like waterfalls, thunder, or wind, or add low-frequency content to synthesized sounds.
- Modulation: Brownian noise can be used as a modulation source to create random fluctuations or movements in parameters like pitch, filter cutoff, or amplitude. Since its energy is concentrated in lower frequencies, the modulation will have a slower, smoother character compared to white noise.
- Randomization: Brownian noise can be used to generate random control voltage signals, which can be useful for introducing random variations in a patch, such as random pitch sequences, filter sweeps, or amplitude changes.
Brownian noise can be generated by dedicated noise generator modules or by using filters and other processing techniques on white noise sources.