You guys are prolly all off for the weekend now and I am stuck with a game I cannot enjoy :(
However, I have done testing of my own and come to the following conclusions.
Having gone into the "sound" folder and tested playback of many files using various players, I am pretty sure that the issues lies with playback and looping ... for example a "marching" sound of the units is produced by looping the same sound files over repeatedly - the problem is that it seems to be cutting itself before the file finishes playback and/or looping too quickly ... the result is a sound that is just annoying rather than sounding anything like marching.
You can hear the same during combat ... the "chink" of swords hitting swords cuts itself off and noises from the men also cut-out before playback is fully finished.
This is hugely frustrating because prior to the patch and this new sound engine the game worked flawlessly for me and I was thoroughly enjoying it.