I would recommend W. Sidney Allen, VOX GRAECA: The Pronunciation of
Classical Greek (Cambridge: University Press, 1968) (3d ed., 1987).
There is extensive and well-reasoned treatment of the primary evidence.
-- Stephen C. Carlson : Poetry speaks of aspirations, email@example.com : and songs chant the words. http://www.mindspring.com/~scarlson/ : -- Shujing 2.35