A keyboard may be an instrument in its own right (an electronic keyboard) or part of an instrument worked by hammers, plucking or bellows.
There are keyboard instruments beginning with C, H, O, P, S and V.
A klaxon is noisy and sometimes introduced into music.
World music provides more instruments for the letter K, but I am not familiar with them.
As I tap this out on the keyboard of my laptop, I am making percussive sounds in irregular rhythms. Old fashioned typewriters clacked and rang a bell as the end of each line was approached. That led to a piece of humorous music – the typewriter song.