The Effect of Source Directivity and Side-Wall Scattering on Binaural Hearing Objective Measures

The perception of sound in architectural spaces is influenced by two main factors: the properties of the space in which the sound is produced, and the properties of the source producing the sound. This research project uses computational modeling to study the effect of these properties on the binaural response in a virtual space. Two independent parameters were studied: the scattering coefficient, which quantifies the ratio of the sound energy reflected non-specularly by a surface to the total reflected sound energy, and a new parameter developed for this research that characterizes the source's directivity, the Lateral Directivity Index (LDI). LDI is the logarithmic ratio of two intensities: the intensity of sound emitted by the source that undergoes only a first-order reflection before arriving at the receiver, and the total intensity of the source. This parameter is a function of both the source directivity pattern, and the relative positions of the source, receiver, and reflecting surface. The Binaural Room Impulse Response (BRIR) for several scattering coefficient and LDI combinations have been computationally generated and subsequently analyzed. The results for Reverberation Time, Early Lateral Energy Fraction, Early Interaural Cross-Correlation Coefficient, and Lateral Strength show a variety of singular and interaction effects between LDI, scattering coefficient, and simulated objective measures.