Requirements for low-frequency reverberation in spaces for music: Part 2: Auditoria for performances and recordings.

Abstract

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.

Requirement for low-frequency reverberation in spaces for music: Part 1: Smaller rooms for different uses.

“…In group conversation and ensemble play, the resulting Lombard effect will otherwise inevitably trigger the loudness spiral, well-known by teachers among a class as well as by conductors in front of an orchestra. Another wave interference effect at low frequencies that affects the sound quality in larger spaces for music performances will be treated in Part 2 of this companion paper (see Fuchs & Steinke, 2015). This document is copyrighted by the American Psychological Association or one of its allied publishers.…”

“…In a most recent paper on the effect of lf reverberation and noise on speech intelligibility in classrooms, Wu, Peng, and Bi (2014) found out that lf noise with a 15-dB rise at lf down to 63 Hz above a flat “white noise” spectrum with the same sound pressure level reduced intelligibility by about 40% for a room with a reverberation time ( T m ) of 1.2 s at mid frequencies (500 to 1,000 Hz) and a bass ratio (BR; see Part 2 in Fuchs & Steinke, 2015) of 1.22, but by only 32% for BR = 0.86 at the same signal-to-noise ratio (SNR) of 0 dB, whereas the corresponding reductions for white noise amounted to 37% and 27 dB, respectively. Table 1 also displays that reducing T m to 0.6 s could raise the intelligibility score by about 10% for both noises.…”

“…The clarity of music is not as straightforwardly qualified as the intelligibility of speech on Table 1. A “bass rise” may even be welcomed as giving the music acoustic “warmth” (see Part 2 in Fuchs & Steinke, 2015, and section 5.13 in Barron, 1993). In an early proposal for the design of broadcast studios for speech and other purposes, Beranek (1955) consequently reported, “BBC experience that the reverberation curve should be reasonably level, and that a (sizable) rise at low frequencies causes bass masking, especially in music with heavy scoring in the bass” (p. 551) and recommended the reverberation time characteristics in Figure 5 as based on studies of Kuhl (1954) and his own experience.…”

Zum Bassverhältnis in akustisch herausragenden Konzertsälen

“…Dies kann nach Gl. (6) und (7) sowie Abb. 5 und 6 aber wohl nur im höheren kHz-Bereich gelungen sein.…”

Guest editors’ introduction to the special issue on “performance spaces for music: Acoustical and psychological measurements and their interactions” honoring Dr. Leo Beranek.

“…Two related contributions from this field have been included in this collection. Part 1 is Helmut Fuchs and Xuequin Zha’s (2015) paper “Requirements for Low-Frequency Reverberation in Spaces for Music”; Part 2, by Helmut Fuchs and Gerhard Steinke (2015), focuses on low-frequency reverberation in small spaces for music and in auditoria designed for both performances and audio recordings.…”