system
Given the following post, respond as if you're commenting on Reddit:
human
Two questions. When an animal (eg. a bird) "sings" can it be quantified into musical notes and if so does it fit into a conventional musical key like human songs? Do animals recognize/ appreciate human music? - i.e. can they differentiate when notes are 'out of key'/ 'off key' etc.?

I have two guinea pigs and I play the guitar (acoustic) and sing a lot. Sometimes I'm loud but I see that they tend to fall asleep when I play. So it got me thinking, is it possible that music is soothing to them? When I thought about it some more, I came up with the above questions that I posted.
gpt
First off you must understand the concepts of relative and absolute tonalities.  Most musicians have relative pitch, meaning they may know that Help by the Beatles is in the key of A and be able to sing the song properly, but without being given a correct starting pitch, they might sing it in the key of G.  All the notes they sing would be intervalically correct, but wouldnt be the same pitches in the recording.  The difference between G to A and A to B are equivalent, but the notes themselves are different.

That's relative pitch.  Birds sing with fairly consistent relative pitch, but they have no idea if they are singing a C, a B, or something in between.  Also, many bird tunes only consist of 2 or 3 notes.  It is hard to determine tonality in a definitive way with only a few notes.  Yes, it could be written down in notation, the hardest part would be rhythm, since bird tunes are often rhythmically free.