School music rehearsal spaces—How dry is dry enough?

Abstract

Handbook values for optimum reverberation time (RT60) in a music studio, such as a school band or chorus rehearsal space, fall into the 0.8 to 1.0 second range, depending on volume. One music room furniture manufacturer specifies RT60 values as high as 1.91 seconds. We submit that these RT60 values are excessive. The Classroom Acoustical Standard (ANSI S12.60-2002) specifies a maximum allowable RT60 of 0.7 seconds to achieve good speech intelligibility. Obviously, good speech communication is necessary for effective education of any kind. In special function rooms designed for music instruction, experience has shown that the design target RT60 should be as low as 0.2 seconds, for frequencies of 500 Hz and above. The requirement for such low reverberation is dictated by the need to reduce the extremely high sound levels that can be generated by a large group; and to give the instructor a dry environment that provides the ability to isolate, identify, and evaluate the musical performance of an individual student while rehearsing in a larger group. This allows the instructor greater opportunity to reinforce good student musicianship and to correct individual student mistakes, ultimately resulting in a higher level of concert performance. Sonic examples are given.