I have made a frequency sweep to try to identify some distortion I was hearing on my 3G iPod.

I made a 9 kHz - 14 kHz sweep lasting about 20 seconds in AIF, and imported it into iTunes. I then converted it to AAC at 192k. It sounded just fine in both the AIF and AAC formats. I listened on both my speakers, and on my Shure e3 earbuds. In both formats, it sounds fine: Clean and Pure, no overtones on either the speakers or the e3's.

When I update these onto my iPod, BOTH formats (AAC and AIF) sound horrible, on both my e3's and my speakers. There are horrible overtones (louder than the sweep itself), rising and falling, and other loud artifacts.

EQ was OFF on both iTunes and the iPod.

I repeat, iTunes handles these just fine, but the iPod does NOT.

Any ideas?