hey. i just had the exact same thing, i think i found the answer on another discussion thread, or on a google search. Sims 2 uses midi sound, and some apple apps do too. the apple apps often change the hurtz to a number that is too high for the sims 2. goto your untilities folder in applications. open the audio midi setup application. on the bottom left side change the properties for: to read built-in output, and then on the bottom right side, change the drop down menu to format: 4410.0 Hz.
That should do it. If not, there was something else I read, but I'd have to go back and find it. This method worked for me though.