Mixing is done by summing. When you add two identical waves the height at 45-degress gets added together, and the height at 90 degrees, 0-degrees, etc., and all points in-between. (With digital, you simply add the samples together.) So, you get the same waveform only bigger (louder). If the phase is shifted, you’ll get a smaller sum but the same wave-shape. If you shift it enough to where you are adding negatives to positives you can end-up with a smaller (quieter) waveform, or if you shift 180-degrees and everything sums to zero, you have no waveform.
I’ll be honest with you the reason I am asking is because I am interested in white noise. I think it’s interesting when you combine all frequencies together you call it white. Similarly, in vision you combine all wavelengths of light and you get white light.
Audacity can generate white nose - Generate → Noise.
With enough frequencies (maybe 1000 or more?) and enough randomness, you could probably simulate white noise. But normal music contains hundreds of frequencies* at any moment in time, they are not random, and they don’t sound like noise… Well… most musical genre’s don’t sound like noise!
Color perception is different from sound perception. If you play two (or more) tones at once (or two or more instruments at once), you can hear them both. When you mix two (or more) colors together, our brain cannot see more than one color (at any one location), so somehow our brain creates a 3rd color.
If you look closely at an old color TV (or computer monitor) with a picture tube, you will see that there is only one colored dot (red, blue, or green) at one location, but at a distance we can’t focus on the individual dots so we perceive different colors as the dots/colors blur together.
Normally, digital white noise is just a completely random sequence of numbers which turns into white noise (a completely random waveform) when fed into a digital-to-analog converter. The [u]Digital Audio Tutorial[/u] shows you how digital audio works. If you generate the samples randomly, you have white noise.
Pink noise sounds more natural than white noise (maybe perceived more like white light). Pink noise is has equal energy in each octave… i.e. The octave from 100 - 200Hz contains the same energy as the octave from 10,000 - 20,000Hz. Pink noise is created by generating white noise and then filtering it.
- A musical instrument or human voice generates many frequencies at once in addition to the fundamental tone we perceive as pitch. It’s one of the reasons a guitar sounds different from a trumpet when they are both playing the same note, or why two singers never sound alike although they are singing the same notes.