This example shows a way to visualize the pitch of a MIDI note on the x axis of a lcd object. The same thing could be done in Jitter with jit.lcd. Whenever you're trying to visualize music or sound, some decisions have to be made about how parameters from one domain (music) will be mapped to the other domain (image). In this case, we've decided to visualize pitch in terms of a circle's left-to-right position.
In this patch the zmap object changes the scale of the incoming number stream from the ctlin object from the standard range of MIDI (0-127) – the 0 is bypassed so that it is translated properly once the range is mapped back to linear amplitude – to a specified range in decibels – in the case of the example from -63 to 0 dB.
Here are three ways of generating MIDI notes. Admittedly they don't result in very interesting music, but they show ways how numbers can be converted for usage as pitch information.