Comment by ddingus

A screen reader could use various aural means of emphasis that I bet would be as effective as this "color by pattern" idea is.

We have pitch, volume, enunciation speed, and for the voice itself the vocal formant frequency can change as can the harmonics. And that is a rich field we are good at differentiating in too.

One other screen reader idea I had upon seeing this is to use a brief sound either immediately before or after, maybe even slightly overlapping the vocalization.

30 [30 MS BEEP] CO [30 MS BEEP FOLLOWED BY A SHORT CHIRP THAT INDICATES A KNOWN ADDRESS]

Writing that out looks messy. All I can say is the sounds in my head right now make a lot more sense and would compliment the colors nicely.