Brady and Darwin (see Darwin, C.J. The Perception of Speech, in E.C. Carterette, and M.P. Friedman,Handbook of Perception, Academic, New York (in press), Vol. 7, report shifts in the phoneme boundary along a synthetic voicing continuum as a function of the range of stimuli presented within a test. The present study reports comparable shifts along synthetic voicing and place of articulation continua. Implications for the interpretation of adaptation boundary shifts are considered.