Test your hearing range! A series of pure sinewave test tones covering the audio spectrum from 20 Hz to 22 KHz, each preceded by a vocal announcement giving the frequency of the following tone. Tones created in Cool Edit Pro. PLEASE:- 1) Download the file, don't try the test using the Freesound preview. 2) You need a decent quality sound card/interface or you may well be hearing false sub-harmonics at the top end of the test.
When you listen to the sounds before downloading (on the site), you're listening to mp3 or ogg previews of the sounds encoded in relatively low bit rates to save bandwidth. No (dynamics) compression is applied at all out of that that the mp3 or ogg encoder itself might add (which should be minimal or none).
When you download the sound you get the exact same original file that was uploaded, no transcoding nor any kind of editing at all, without the squeaking.