Phaser?

Hey guys, so I was making metal as I do, and i noticed this weird phaser effect with guitar. always trying get weird sounds out of flat i had to find out what it was,

So my conclusion if you have 2 of maybe the same kind of instrument (havent test diffrent kinds with this technique) if both instruments are playing the exact same note with tremolo it causes a wavy effect like a phaser later on in the test youll see trumpet hit g7 even sounds different depending on the glisses I personally want to make a whole piece with this but I will have to study further, thank you have a good day