John Bassett

An ambisonic microphone was used to measure the degree to which a sound field varied with direction within a reverberant room. The apparent diffusivity of the room was varied by incrementally adding reflecting panels, according to AS ISO354 2008, producing seven different room states. In each reverberation time was measured using three loudspeaker positions and four measurement microphone positions, according to the interrupted noise method outlined in AS ISO354 2008. Recordings were made of sinusoidal sweeps for the three loudspeaker positions with a first order ambisonic microphone at three different positions in the room. The recorded sine sweeps were converted to impulse responses to measure the evenness of the sound field around the microphone in each room state. These results are compared with the traditional method of establishing a diffuse state in a reverberation room with a view to the development of a more direct method for establishing an isotropic state in reverberant rooms.