An experiment in the use of resilient materials in orchestra riser design

Abstract

An experiment was assembled under extremely limited time and space constraints to investigate the acoustic effect of resilient materials in orchestra riser design. The riser was a portable, box-type riser for assembly on a flat concert platform, not a lift-type riser. The primary goal of the inquiry was to maximize lateral vibration transfer through the riser (from celli, basses, etc.) without detrimentally affecting airborne sound radiation from the riser. A portion of a full-scale riser was mocked up, including sections of differing elevation. Various design configurations of the riser allowed experimentation with and without resilient materials, and with resilient materials placed at different positions within the riser structure. The experiment was conducted within a reverberant volume. The riser was excited by mechanical shakers and by a cello, independently. Vibration measurements were captured using accelerometers on the riser, and airborne sound pressure levels were captured by a distant microphone. Initial results suggest that the use of resilient materials in certain configurations can considerably increase lateral vibration transfer through the riser (as compared to rigid construction), without significant compromise to airborne radiation from the riser.