Richard H. Lyon
MIT and RH Lyon Corp., Cambridge, MA 02139
All systems of finite extent are multimodal, but many have modes so sparsely distributed along the frequency axis that one can safely deal with them one mode at a time. This is the classic situation in the dynamics of machine structures. On the other hand, some systems have modes so densely spaced that statistical and asymptotic theories such as the geometrical theory of room acoustics provide powerful models. The low modal overlap theory of Bolt, and the high modal overlap theory of Schroeder for the transfer function magnitude in rooms represent these limits in room acoustics. There is a similar transition in behavior in the phase of transfer functions as one proceeds from low- to high-modal overlap. This process will be described in the discussion.