Excluding the human voice smile , what about the earliest stringed instruments from which all other ones(guitar, violin...) originated, such as the lyre. Heck, a piano is a stringed instrument when you think about it. In modern history, the electrification of the guitar is a biggie...much influential music was performed on them esp thru the 50's, 60's and 70's. Of course, in very modern history you should look no further than auto tuning, the greatest thing to happen to people with no singing talent.

Half of communication is listening. You can't listen with your mouth.