Why does this mp3 file pass ACX check, yet I sound like I'm under water?

Can someone please explain to me why this file sound like it’s muffled or I’m underwater? I would love to use this mp3 file as it passes ACX. Can I remove the muffling somehow? (I did go to some online converter site to convert the uploaded mp3 file as it was too big to upload in its original size. It didn’t have an effect on the sound though.)

IMO the whistling distortion on that is not reversible.
Possibly some sort of extreme noise-reduction / echo-cancellation has been inadvertently applied by the MacOS.

Not necessary to do that, just select five seconds or so of the big file in Audacity …


Some of the online-converters give a free gift of adware/malware when you download the processed file.

Yeah, I probably have to ditch that file. Sux… Thanks for trying to help, Trebor.

Skype (or similar) is another thing than can apply live noise-reduction / echo-cancellation, even if you didn’t ask.
( I don’t speak Mac so can’t tell you where to look for those unwanted audio enhancements on your computer ).