Ok, let me explain what happened here. This is the path you reported above:
C:\Program Files\HTC\Aces High\sounds\HTC\Aces High\sounds
When you install AH, you should have a path like this:
C:\Program Files\HTC\Aces High\sounds
Beneath this will be sounds, plus folders for different planes and such.
What happened in your case is that when you unzipped the sound pack, it expected to be unzipped in the Program Files directory, not in the Sounds directory, so it made the whole path structure beneath sounds again.
Solution:
From here: C:\Program Files\HTC\Aces High\sounds\HTC\Aces High\sounds
Cut everything (folders and files) and paste them in here: C:\Program Files\HTC\Aces High\sounds
Say yes to overwrite... yes to all to be faster.
That should fix you up.
After that is done, go to the C:\Program Files\HTC\Aces High\sounds folder and delete the "HTC" folder and everything beneath it. Make sure you delete the HTC folder beneath the sounds folder, not the one in Program Files, or you'll vape the whole game.