Why did you bother with this comment? Did you actually listen for the squeaking yourself? For the record, I did listen with different headphones and DACs before

Why did you bother with this comment? Did you actually listen for the squeaking yourself? For the record, I did listen with different headphones and DACs before I posted here. As for whether I imagined it or not, frequency analysis on sections where I hear the squeaking shows an isolated peak at around 13.5khz. This peak is absent in sections and tracks where I don't hear the squeaking. I also applied an equalizer to the track, to amplify the squeaking. The chirps become clearly audible when this is done.