Effect of early reflections from upside on auditory envelopment

Auditory spaciousness is primarily dependent on the strength of early lateral energy. The difference between the degree of spaciousness caused by only lateral reflections and that caused by lateral and ceiling reflections, however, has not been definitively clarified yet. In this paper, a series of psycho-acoustical experiments is performed to examine the effect of early reflections from upside on spaciousness with lateral reflections. The results show that a single reflection from upside causes a vertical spread of sound image and auditory envelopment becomes stronger as vertical component of reflected energy increases when lateral energy fraction and listening level are constant.