I can also confirm that this fixes the sound problems.
To those few of us who do not know where to find the file (like myself) try this:

Navigate to your Steam Folder > steamapps > common > Counter-strike: Source> hl2 > Sound > Then delete sound.cache

Copy-paste for the Lazy people: D:\Steam\steamapps\common\Counter-Strike Source\hl2\sound
(change D:\ to the Directory in which your Steam Folder is located)