Richard H. Bolt’s work on theoretical aspects of room acoustics

Abstract

From about 1940 to 1950 Dick Bolt undertook a number of studies of the transmission of sound in a room. These were mostly theoretical and appear to have had two sources of inspiration: the work of Wente at Bell Laboratories in the 1930s, and Philip Morse’s work on the eigenfunctions and eigenvalues of idealized rooms in the early 1940s. In 1944, the Reviews of Modern Physics published in its April issue a single paper—that of Dick Bolt and Phil Morse, titled ‘‘Sound waves in rooms.’’ This tour de force took the viewpoint that a deterministic calculation of the modes of an idealized room could reveal important features of the acoustics of less ideal spaces. The relations between wall impedance and modal damping for axial, tangential, and oblique modes and the construction of direct fields from modal expansions are worthy of special note. Perturbation analysis is used to couple idealized modes as a first attempt to deal with ‘‘real’’ rooms and the transition to ergodic behavior. This work then led Bolt to a number of studies of the irregularity of spacing of modal resonance frequencies, which had some influence, in turn, on models of modal distributions in Statistical Energy Analysis.