If we have to associate a noise with a color, the first (and probably only) example that comes to mind is the famous white noise. However, the truth is that noise can have other colors, depending on its spectral power density. That is how we find pink, red, blue, violet, and gray noise. Do you want to know how some of these colors sound? Here are a couple of videos.
Why is white noise called "white"? How does it get associated with a color? In reality, it's simpler than it seems. Both light and sound are made of waves. Just as white light represents all frequencies we can "see", white noise does the same with all frequencies we can "hear", which normally range from 20 to 20,000 Hz. Added to this is the detail that all those frequencies have the same power, but the reason white noise sounds the way it does (that is, static) has a biological component behind it. Now, for many people white noise is very annoying. What if we try another color…?
Explaining the colors of sound
One of the most popular is pink noise. Unlike white noise, pink noise loses three decibels per octave as frequency increases (its spectral power density is inversely proportional). In other words, higher frequencies have a reduced volume. Although it may seem unbelievable, that reduction gives the sensation that pink noise is more balanced than white, when in fact it is not.
Red noise, wrongly called 'brown noise' (technically 'Brown noise' after its discoverer Robert Brown), places even more pressure on higher frequencies compared to pink noise, losing six decibels per octave.
White, pink, and red noise are considered the three main ones, but the story of noise and colors does not end there. Both blue and violet noise are 'opposites' of pink and red noise, increasing by three and six decibels per octave respectively. If we look at the graph of gray noise, in essence we find a curve. And as for the rest… let's say they are subject to interpretation. Many call silence "black noise", but not everyone follows that rule.
