There used to be CD-ROMs called Red Book Audio discs (because the original specifications for CDs came in different colored books and this one was red) that had CD-ROM data as the first track and CD-Audio data for the rest of the tracks. This is what allowed DOS and early Windows games to have CD quality audio at a time when MIDI and FM synth were the primary computer audio sources (the PlayStation and Saturn also could work this way, later consoles didn’t use CDs specifically). They would just play the CD through your speakers while you played the game. For most of them this meant you could change the disc and have it play different music (but always the same track number it would have played anyway).

There was a small problem with these discs though, if you put them into a non-computer CD player to listen to the music and accidentally played the first track you may blow your speakers. This actually happened to me in my mother’s Windstar (late 90s mini-van) with the Descent disc. (Or maybe Descent 2?)

TL;DR - The ability to read an ISO track as audio or data is a quirk leftover from the original CD specification.

.iso are basically disk images and can hold movies, music etc…

I mean, you can interpret any file as an uncompressed audio file. It's all 1s and 0s at the end of the day. That's probably what is happening here, judging by that runtime.

I used to import random files into audacity to get interesting glitch sounds to further process when I was doing EDM production. Since data is normally structured in some way, patterns will result in changing tones or patterns of tones.

VLC can play DVDs dumped as .iso files.

You might want to right-click on the .iso file and chose "mount".