Which Development Most Revolutionized Music?

i vote invention of audio ("tape"). for the above reasons. imo, much more important than anything that came afterward, since those were just improvements over the original.....in second place is written music, however i'm pretty sure that mostly only classical music was preserved in this way, so tape would've been much better if it was available then to the commonfolk. also, internet definately revolutnionized music distribution, so i'd put that 4th, after radio.

Atavachron wrote: from your list I'd say the phonograph, but I tend to think it was electronic amplification

Actually, three hundred years ago music was played a lot in theatres and the most successful stuff was spreading very fast by oral means. And it was also the snobbery - everybody wanted to see other people at the theatres, and wanted to be seen. There were the good seats, for nobles and other fancy persons, and there was the gallery where everybody could come (it was very cheap). It was unlikely, at that time, that one wouldn't attend to various shows. I'd say that the phonograph and the radio were not that big of a revolution. They brought music to the people, but before people used to go for the music.

I'm leaning towards the phonograph or some other form of recorded sound.  Being able to hear a musical performance without being in the presence of the band or musician outweighs written music, in my opinion, because the audio recording means more to the general public than written music (which not everyone can interpret). 

However, written music (traditional or some form of tabulature) makes it easier for musicians to share musical ideas with each other instead of saying "put your fingers here" or something similar.

Hard choice, but I'll vote for the phonograph.

I went with tape. I can't imagine all the music that has been performed in the past and had to be a one shot recording due to not having tape that has been lost.  Written music is important but for me that is a given. Modern music existed for hundreds of years prior to tape. Tape made it possible to save that music for future generations. Just my humble opinion.

^ But that only revoplutionised the way we listen to music.

Written music by far. I think that started around Byzantine and Gregorian Chant, and we've been in for a great ride ever since