Sound Field Diffusivity Assessment in Non-Stationary State by Measuring Nonuniformity of Sound Decay Curve

Methods of sound diffusion assessment presented in literature require information on directional properties of the sound field in stationary state. These methods are complicated and not often applicable in measurement practice. Measurement of the sound field diffusivity during its formation can be assessed from sound level decay curve deviation from a linear shape. With this method, the degree of diffusivity has been determined in three rooms. Measurements were performed in rooms differing in volumes and sound absorption. Changes in sound decay uniformity were noted, which can be translated into diffusion coefficient changes. Results indicate that diffusion increases as room absorption decreases. Diffusion does not depend on room volume. Changes of sound decay uniformity follow trends that are well described by power function.