Architectural Acoustics: Effects of Specular & Diffuse Reflections on Perceived Music Quality

Sets of impulse responses were designed/simulated with different temporal distributions of early acoustic energy (specular and diffuse reflections); then, three types of anechoic sound sources: orchestral music, trumpet, and piano were convolved with the designed impulse responses. The results from the listening tests revealed that different room environments were needed to acoustically support different source characteristics: 1) A large number of diffuse reflections arriving within 40 and 80 msec of the direct sound improved perceived “intimacy”, “texture”, and “overall impression” for all sound sources; heightened perceived “clarity” for trumpet and piano; and reduced perceived “glare” for trumpet. 2) Diffuse reflections arriving between 80-160 msec of the direct sound preserved perceived “reverberance” and reduced perceived “echoes” as opposed to specular reflections arriving at the same time period. The results of this study indicated that music performance halls should be designed to include diffuse reflections from surfaces within the 80 msec time period to achieve preferred texture, intimacy, clarity and overall impression and in the 160 msec time period to reduce echoes.

Dr. Pattra Smitthakorn obtained her Doctor of Philosophy degree in Architectural Acoustics in 2006. She afterwards returned to Thailand, and worked as an instructor at the School of Architecture and Design, King Mongkut’s University of Technology Thonburi, Bangkok.