I would probably say the keyboard for creation because theres no sound it cant create. Every numbnut on the planet has released some sort of dance single and made a mint of sheer copyright exposure. The walkman for sheer ease of distribution. The guitar because its a good insturment. Rock N Roll because now ALL music is based on it... The 4/8 Track recorders because they allowed the true birth of home recording...

Funnily enough I had been working on an Op-Ed along these lines, but it goes further back in time. If we are to stick by the rules of this post (50 years) then very few of the inventions mentioned count. (I have been doing my homework folks!) First of all, the fender is a product that contained new technological innovations, but it was not a completely new invention. It was not the first electric guitar or even the first solid body electric guitar. Also the Fender appeared 3 years too early to count, the Telecaster arrived in 1951. The Guitar itself is definitely older than 50 years Optimus! The keyboard? synthesisers and electronic instruments can trace their history back to 1870. The apple Mac? Nah, took a while before they became good and cheap. The original Atari ST with its built in Midi interface was very useful for sequencing and its killer App, Cubase is still in use today. Rock N Roll is older than 50 years, and not really an invention as such. The walkman was a lovely "product" but only really a miniaturisation of the existing tape player. It changed listening habits, but did it change music? Multitrack recording is not that new, though I will admit that cheap multitrack recorders are only a relatively recent thing. In the last fifty years, I think one of the most interesting developments that has changed music itself it software based recording and synthesis. But if I were to go back further than 50 years, what would be the all time most important inventions? Recording (though Edisons system was actually originally mechanical and later refined with electrical improvements), Radio and electronic amplification. Damn, I've runied the Op-ed now haven't I? Ah well, probably was never going to get around to finishing it. These three inventions not only allowed easy storage and distribution of music, but changed music itself. I'd also stick the concept of copyright in there too, its part of what makes the "music industry" as we know it possible.

I would say then, Dr Binokular, that the Printing Press is a key invention since it allowed the dissemination of ballads and then sheet music

I never figured you to be pedantic binokular but there you have it. I didnt realise we were being literal about the "50 years" thing. Twas my understanding that is was more general. And rock & roll is an invention. So there.

Jules, gotta disagree because sheet music requires the ability to play an instrument. Recording allows a much larger audience of passive listeners who only need to appreciate music, but do not need to posess any musical knowledge whatsoever. Also sheet music is open to interpretation and allows you to play music in your own style. Recording on the other hand allowed a cross pollination of styles, people got to hear music played differently or got to hear folk music that was not published as sheet music. For example, bluesmen were influenced by hearing hawaiian music which can be heard in the use of steel slide guitar playing. Blues bacame Rock and Roll and to a lesser extent influenced reggae. I doubt these influences would have travelled so fast without recording and wireless radio.

Not true. Buddy Holly. Little Richard. Blue Oyster Cult. Elvis. Reinvented music. Which means that they thought HARD about their sound because they wanted to be new and fresh. You stand corrected sir!

You know Little Richard said "Rhythm and blues had a baby and somebody named it rock and roll." Buddy Holly was a genuine innovator in terms of his guitar style, but cannot be credited with inventing Rock and Roll Blue Oyster Cult? ummm... bit late for the dawn of rock and roll? hardly that innovative either. Elvis? A great performer, possibly the most iconic of the 20th century, but wasn't he really just a white ambassador for what was regarded as black music? These guys did think about their sound, but no one really can claim to have invented rock and roll.

Wasn't saying the blues was Hawaiian Jules! (now THERES an off the wall idea!) just the use of a slide style using steel guitar, but thats just a theory some people have, it may have had nothing to do with it as you say, slide steel playing may have just developed side by side in two different places.