PS...

Open these files in an audio editor... laugh your socks off! Not even CLOSE to a sine wave. Plus, original files are 192kbps MP3's at 44kHz sample rate. Why couldn't the poster just post .Wav's at 16bit? Might have been a bit more sine-like (24bit @ 48k would have been better, too).

Bottom line is, once you are in the digital realm, pure sine waves at these kinds of high frequencies are impossible to produce. You are getting too close to the Nyquist limits of the technology, even at CD quality. This is why you'll see real analog equipment in reputable audiologists' labs. Only they are capable of generating tones without spurious artifacts.

Google test tone wav to get to some sites that offer free CD quality test tones, if you like. But open up any past 10kHz or so in a decent audio editor (one that shows the ACTUAL sample points) and you'll see why those audiophiles still like their analog playback systems!