I know there is debate over the role of music, such as vocal music generally being viewed as acceptable, but instrumental music generally viewed as unacceptable. Has Islam's role or stance towards music changed over time? Does the Islamic stance towards music differ in different countries such as Turkey or Egypt?
I guess you better ask /r/islam although music is one of the topics taht they rather not debate.
Music in Islam is really complicated, some say it's not forbidden as long as music doesn't encorauge you to do anything that Islam forbid, althoug many have seen music (especially today) has more mudarat (more or less means 'useless'). But keep in your mind that music and art were used to spread Islam in many nations. Even today, music is used to spread the teaching of Islam. In Islam, tehre's something called Tilawah which means reading the Quran with melody. It's quiet a complicated art especially because Arabic is a very complicated language.
The more extreme views forbid it completely, no matter what the lyric said. Sami Yusuf is dubbed as Islamic rock star, and some of his songs citing Quran and Hadits verses, but that doesn't mean his free from controversies. Even sometimes, extreme Muslims forbid tilawah, or reading Quran with melody.
Every Islamic majority nations have their own views on music. Indoneisa and Malaysia for example are more liberal on music, although mainstream music might be censored if it's using nasty words for example. Iran is forbiding music unless songs with religious values.