4049 buffer circuit

[dylar]

I  just built a tiny Cacophonator and it works fine.  I'd like to build an input for it, which has been done - however there are no schematics.
The input was built using a 4049 chip to make a buffer for the input signal.  I noticed a few other circuits around here use these.  Can someone explain what they do?  And is there a "standard" buffer circuit that is typically used (and if so can someone point me to a layout?).
Here's a vid of the cacophonator with input:
http://youtu.be/q_s4U-8V2Gg
and here is the layout for the cacophonator with input (there are no part values available - which is why I ask if there is a standard buffer)