Auditory receptive field mapping The Wikipedia page on sound localisation states:


  Localization accuracy is 1 degree for sources in front of the listener
  and 15 degrees for sources to the sides. Humans can discern interaural
  time differences of 10 microseconds or less.


However, I can't find any more detailed information on localisation accuracy.

What I'm after is a plot of accuracy (Y) against azimuth (X).

Can anyone get me one step towards this information?

π
The ultimate book on the topic is probably http://www.amazon.com/Spatial-Hearing-Revised-Psychophysics-Localization/dp/0262024136 . It's a bit dated but contains and excellent review of the main psycho-acoustic research on spatial hearing. 

It is a very complicated topic. For example azimuth and elevation perception work completely different and hence azimuth resolution is quite a bit better than elevation resolution. The actually resolution (or jnd for just noticeable difference) depends heavily on the actual and the properties of the signal.