The above sound files in RealAudio demonstrate the sound of two hands clapping the keys.

Below are two sound files demon-
strating the sound of first two, then four hands applying their skill to the same song.

Using a YAMAHA DISKLAVIER, I have been able to record a popular old song, and then, through the miracle of technology, record a second piano part -- thus creating a four-hand rendition of... 

AFTER YOU'VE GONE two-hand version	AFTER YOU'VE GONE four-hand version

 Even though either rendition can be considered only a rough draft of musical thought, you can see how dramatically a dedicated, even whimsical, second part can change a composition or recorded performance.