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

Abstract

(ProQuest: ... denotes formulae omitted)A large number of contemporary concert and assembly halls are criticized for their mediocre acoustics, although most elaborate model tests and computer simulations are at our disposal for the large-scale planning and small-scale interior design of an enclosure. On the other hand, we have inherited numerous spaces with excellent acoustics that were built without any powerful prediction and calculation tools. Acousticians or sound engineers may complain that nowadays, architects almost exclusively consider the visual of a structure. Only rarely do they consider the acoustic aspects (Blesser & Salter, 2007, p. 1). But are we able to provide the builders with a firm and generally applicable guideline for achieving acoustical quality and comfort in a room for a specific musical or lingual destination?Concerning the less concrete, more complicated sonic processes such as hearing (meaning, the detection of sound) and listening (as active attention or reaction to the meaning, emotions, and symbolism contained within sound), one may refer to Blesser and Salter (2007) for a profound synopsis of the various of architects, interior designers, and sound engineers. As an acoustician, one may retreat to the standard International Organization for Standardization (ISO 3382, 1997) on p. 2: This standard continues to specify room acoustic quality by reverberation time T alone . . . T measurements are important in the field of noise control (e.g., in public buildings, libraries, swimming halls or work places) as well as for the assessment of rooms for speech and with... (1)where V is the room volume in m3 and both T in s and the equivalent absorption area A in m2 of the room are strongly frequency dependent in the range between (at least) f 63 Hz and 8,000 Hz relevant for room acoustics in general. ISO 3382-1997 in its Note 17 states, The frequency range should include the octave bands from 125 Hz to 4 kHz or the one-third octave bands from 100 Hz to 5 kHz. In concert halls the 63 Hz octave band should be added. When it comes to additional quantities, meant to be subjectively important according to ISO 3382-1997, Annex A, like early decay time, strength (G), clarity (C80), definition (C50), center time TS, and lateral energy fraction (LF), however, the focus is only on a much more restricted mid-frequency (mf) spectrum between 500 Hz and 1 or 2 kHz (also for the averaged singlenumber ratings that prevail in practice) intended to summarize measurement results, see Beranek (1996, Appendix 1). As a result, one rarely finds acoustics criteria for the complete frequency spectrum. Instead, standard recommendations usually just refer to a correspondingly averaged Tm as a function of room volume.In this context, Beranek et al. (2010) may be cited:I am convinced that we need to work with the whole spectrum of human hearing-we must not ignore the universes of very high and very low frequency sound that are presently unattended in our data gathering and analysis. Half the instruments of our orchestra have their fundamental pitches below 125 Hz. We need to design for strength in the fundamental sounds of those instruments. Fundamental pitches of low frequency instruments support intonation and bloom for the full orchestral sound. Fundamentals are fundamental! (p. 7)At the same meeting, Bradley (2010) stated that there is not much evidence to support the idea that mid-frequency values are most representative of the perceived broadband changes of all measures (p. 7). Burkowitz (2011), an experienced sound engineer, suggests that recognizing the musical structure and architecture in the contra- and sub-contra ranges is just as important as doing it for the formants (p. 279).The present authors recognize and deal with the prominent role that the performance spaces play in all music making and listening. Hundreds of venues of different size and use have taught them that the complete reverberation characteristic has an enormous impact on any type of music performances, well knowing that modern recording equipment may, to a certain extent, help to cope with adverse acoustics. …