This study experimentally investigates the effects of early lateral and vertical reflections on the horizontal spread (HS), that is auditory source width (ASW), and vertical spread (VS) of a sound image. A psychoacoustical experiment employed early lateral energy fractions Lf and early vertical energy fractions Vf for controlling auditory stimuli. HS increases with a larger Lf. In contrast, the effect of Vf on HS is limited, although HS is larger when early vertical reflections are present. Results also reveal that VS increases with a larger Lf or Vf, but the effect of Lf on VS is greater than Vf .
