Requirements for Low-Frequency Reverberation in Spaces for Music: Part 2: Auditoria for Performances and Recordings

Specular early reflections of low-frequency sound waves are found to destructively interfere with the direct sound field from sources in auditoria. Blurring the fundamental bass lines and masking higher frequencies can be efficiently reduced by providing as strong high-frequency reflections and low frequency absorption as possible at some distance from the stage. One should strive for a "bass drop" in the room's reverberation time as opposed to the "bass rise" that is usually recommended by most standards and textbooks and favored by a majority of architects and acousticians. Representative case studies in churches, broadcasting halls, recording studios, historical theaters, concert halls, opera houses, and rock and pop venues are discussed on the basis of their complete reverberation spectrum (down to 63 Hz!). These exhibit a high degree of acoustic transparency combined with an optimal blending of all instruments and voices, thus yielding an amazingly warm and round sound for the musicians as well as for their audiences.