Audio: red noise (0:02)
red noise plays red noise. The red noise figure shows its spectrogram.
Red noise is unpitched sound in which power is inversely proportional to the square of the frequency.
The spectrogram of red noise is very similar to that of pink noise. The difference is that the red noise spectrogram curves down slightly which means that its higher frequencies have less power than in pink noise.
Red noise is also known as brown noise or Brownian noise. This is because of its similarity to Brownian motion in physics and not because of its colour.
Red noise, like red light, emphasises the lower frequencies. It has a slightly softer quality than pink noise because there are fewer higher frequencies present. It is used to create sound effects which simulate natural sounds containing a lot of low-pitched frequencies such as a waterfall or a roar.