Algorithm to mix sound

Question

I have two raw sound streams that I need to add together. For the purposes of this question, we can assume they are the same bitrate and bit depth (say 16 bit sample, 44.1k

Answer 1

"Quieter by half" isn't quite correct. Because of the ear's logarithmic response, dividing the samples in half will make it 6-db quieter - certainly noticeable, but not disastrous.

You might want to compromise by multiplying by 0.75. That will make it 3-db quieter, but will lessen the chance of overflow and also lessen the distortion when it does happen.