dapphp/securimage — comment on commit 71b9e4aaa65d7ffcef3524f5ca80fea24d4dc330
File: WavFile.php line 456
By Uranium235:

You may want to have a look here for a different approach to mixing audio:
http://www.vttoth.com/CMS/index.php/technical-notes/68

Had really good results, especially with 8-Bit WAV.