Go into the AH file and edit the wave file using your windows sound recorder .
If you have problems doing it that way copy the original wave file to your desktop and adjust the volume, save it and replace the original in the AH program file.
(you may have to rename the file from sound.wav to sound1.wav after you move it to the desktop)
after editing sound1.wav copy and paste it back in AH folder, delete the sound.wav file and the rename sound1.wav back to sound.wav . I don't recall if you can do it directly in the AH without changing the file name but I think you can.)