Red noise, also known as Brownian or Brown noise, is a type of noise signal characterized by a frequency spectrum that decreases in power by 6 decibels per octave (or 20 dB per decade) as the frequency increases. This means that the lower frequency components of the noise have more energy and are more dominant than the higher frequency components. The result is a noise signal that has a deep, rumbling, and smooth sound, often compared to the sound of a waterfall or distant thunder.
Red noise can be generated by dedicated noise generator modules, which usually offer multiple types of noise output, including white, pink, and red noise. In a modular synthesizer, red noise can be used in various ways, such as:
- Modulation source: Red noise can be utilized as a modulation source to modulate parameters such as filter cutoff, oscillator frequency, or amplitude, creating organic, slow-moving, and evolving modulations.
- Sound design: Red noise can be mixed with other waveforms to add texture or used as a sound source for creating ambient and experimental sounds.
- Random voltage generation: By passing red noise through a sample and hold module, you can create a slowly varying random voltage signal that can be used to modulate other modules in your synthesizer.