音乐 is instruments, vocals, 或者 both that make a nice sound and express emotion. Sometimes the emotions aren't as obvious in songs, such as Work, 由 Rihanna. I mean, I have no clue what that song means. Sometimes the emotions can be clear. Some are random. But all of them have some sort of meaning.
To me 音乐 is everything. It's a coping mechanism and it helps spark my creativity. It makes driving 更多 bearable and less boring.
Now if your asking what can be considered music. My answer is much the same; everything can be music. Classical to EDM. If it has a beat and 你 can listen to it, it's music. I even consider the below video to be music.
音乐 is vibrations created for the purpose of artistic expression. Normally, not attributed to non-human 动物 as a creator of music, even though bird noises can be pretty nice lol.
音乐 can be nice, but I also enjoy just background sounds and silence. Its something that I don't mind treating myself every so often, but not as a necessity. It can be a useful tool for learning languages, that it keeps the brain entertained and may loop back certain lyrics to remember foreign words.