modern music history
In 1800s the world accepted western theory(Europe) as a standard theory for everyone, like English in languages which everybody should know to communicate with people from another countries. Thomas Symmes in 1720 developed singing by note, which means the throat is an instrument which has to hit the notes like every other instruments. It had started be popular in church anthems, but later it went worldwide and after many evaluations we have pop stars who also sing by a note for example: Adele. In 19th century the music theory stopped to develop, but what people did with their instruments especially in metal shows that sometimes the sound of instrument and sound style of singing and notes is enough, because there are a lot of people who listen to music to show their style and not for the beatiful pack of notes and this proves that music theory and singing beautifully with hitting the note is not that important as the style of sounds that an artists have. https://study.com/learn/les...