Item — HN Reader

What tools were used to create the audio? For example, the exact patterns of dither-based noise shaping[1] may reveal insight, but are by definition inaudible. Or perhaps there's an ultrasound source - something recorded near old-school CRT monitors may have a 15.75kHz tone, ordinarily outside the threshold of hearing but shows up as a clear peak on a spectrogram.

[1]: https://www.sweetwater.com/insync/hear-effects-dithering/

2 comments

> something recorded near old-school CRT monitors may have a 15.75kHz tone, ordinarily outside the threshold of hearing

Only for some people -- the upper limit of human hearing varies between 15-20kHz, depending on the person and their age. For many children and younger adults (myself included), CRT coil whine is well within our audible range, as an incredibly annoying high-pitched squeal.

This comes up in speedrunning communities sometimes -- many runners prefer to play on CRTs due to their fast response time, and streamers who use CRTs need to remember to set up a notch filter on their microphone, or else their stream may be borderline unwatchable for younger viewers and the streamer might not even realize it.

Interesting, thanks