Terhardt, E. (1983). Absolute and relative pitch revisited on psychoacoustic grounds. In: Proc. 11th Intern. Congr. Acoust., Paris (4), 427-430
Experimental results on both absolute and relative pitch contradict the ordinary view that relative pitch is very common while AP is available only to few individuals. When the experimental task for recognizing musical intervals is organized such that its complexity is comparable to that of recognizing individual notes, the performance of subjects is about equal in both tasks.