RPG Diffusor Systems, Inc., 651-C Commerce Dr., Upper Marlboro, MD 20772
The optimum percentage and orientation of reflecting and diffusing surfaces in an acoustical shell was determined from objective and subjective measurements using conservatory students at the Cleveland Institute of Music comprising two string quartets, a brass quintet, and a horn duo. Objective impulse measurements were made with balloon bursts and five different microphone systems were used to obtain simultaneous DAT recordings. The Head Acoustics mannequin was placed within the group to determine ensemble blend without self-masking. Etymotic Research probe microphones were inserted into the ear canals of musicians to determine ensemble blend with self-masking, headband microphones were used to monitor ensemble blend with self-masking, an omnidirectional microphone was placed within the group as a monophonic control, and spaced omnidirectional microphones were placed in the front of the house to measure the projected sound quality. Analysis of these and other data led to the development of a variable acoustics modular performance shell utilizing reflecting, absorbing, and/or diffusing modules, which allows both variability and flexibility for different stage uses as well as sectional and personal acoustic environments for the performers. This approach was subjectively evaluated with the full Baltimore Symphony Orchestra with David Zinman conducting.