The effect of physical source width on the percept of auditory source width

For decades, research in the field of architectural acoustics has correlated early, lateral reflections with the percept of apparent source width. However, these experiments typically reduce the spatial dimension of an entire orchestra down to a monophonic signal. This approach does not account for the effects of an ensemble's source directivity, arrangement on stage, and physical size. Three experiments were conducted to examine the extent to which the physical source width, as measured by the azimuthal extent of an ensemble from a listener's position, affects the percept of apparent source width. Experiments were conducted for both anechoic and echoic conditions. The experiments reveal that a stereophonic representation of an orchestra creates a perceptually stronger percept of apparent source width as a function of increasing angle. To create an equivalent perception of width under monophonic conditions with two early side reflections, listeners tended to increase the level of early reflections until the precedence effect broke down and the earliest arriving reflection was instead perceived as the direct sound. This result suggests that apparent source width is not merely a function of early side reflections and that the physical source width must be taken into account.