The importance of the direct to reverberant ratio in the perception of distance, localization, clarity, and envelopment, Part one.

Abstract

The component of hall sound that travels directly from a musician to a listener carries information on both the location and distance of the sound source and is vital to both the clarity of the sound and the emotional involvement of listeners. Experiments in laboratories and a hall show that the human ability to separately perceive the direct sound in a reverberant field depends both on the time delay between the direct sound and the reverberant energy and on the direct‐to‐reverberant ratio (D/R). Threshold data for direct sound perception as a function of time delay and D/R will be presented, and their implications for listening room and hall design will be discussed. In large halls the delay can be long enough that the direct sound is perceptable at D/R values less than −10 dB, but in small halls the threshold becomes as high as 0 dB. Consequences for hall design include: early reflections in the best halls need not be lateral, small halls sound better with fewer early reflections (implying the use of non‐shoebox shapes, absorbent stage houses, and shorter reverberation times), and in small halls electroacoustic enhancement should increase only the late reverberation.