Rooms for music rehearsal, sound studios, control rooms, etc., need a smooth frequency response. For that reason, the frequencies of the room modes should be spread as well as possible, and this is controlled by the aspect ratios of the dimensions. The relative variance of the frequency spreading of the lowest 25 room modes is applied as a quality criterion. The results have revealed that the length-width ratio is much more important than the width-height ratio. The length-width ratio should be within 1.15–1.45. The height can be chosen more freely without compromising the acoustical quality.
Find this article in full text from Scitation.