Page 33 - Spring 2019
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Table 1. Summary ofslandard room acoustics parameter: and divided temporally, although
the time periods most relevant to
- - ch erce t are the sub'ect of
in=rd=d P=r°=rnai °°n=i=i= 6“ P P ’
Reyerlieialioii tinie Tune for sound to decrease by so dB, based on N/A ongou-‘g_ rese_arch' Tl? understand
(RT. T10. Tia) linear rii to energy decay (excluding direcl sound the spatial distribution of reflec-
’‘“d ‘’’‘‘1‘‘‘'‘‘ ”“°°“°"‘t tions around the listener, a multi-
Eaily decay time (EDT) siirular to RT, bul based oii initial 10 dB or decay Reyerlieiaiiee char-ii-,e1 i_rr,r,u]se response can be
(including direct sound and earllesl reflections) . . . .
measured with a directional mi-
stre tli G L lh l h iid L dii . .
Cmphom army (Figure 2’ fight)-
Cl 1 (C ) L [h I h ‘ 1 (0 R0 ) d Cl 1 Seveial numerical parameters
any in ogai-i inieraio eweeiieary - nis an any _
‘  standardized by ISO 3382-12009
Early laieial energy Ratio between lateral and total energy williiii l'irsi Appaienl source widili (h"te“'“‘tt°mt O’8“‘“Z“t1°t" for
fmcIr<m(1u) 80 ms Standardization [ISO], 2009;
summarized in Table 1), can be
Lale lateral sound level Logarithmic ratio belween lale lateral eiiergy Listeiier enyeiopineiit . .
(Ll) (allerso rl\S]andl0mlEnel’gy d91'1V€d from i-iTiP“159 1'95P°1'i5€5
measured with an omnidirec-
liiteiaural cross- Biiiaurai measure otsiirulai-ity between sound at Early. apparent soume widtli rionai sound source‘
correlation eoelrieieiil len and riglit ears, reported separately for early s
(!ACCEnrly, ‘ACCLate) (0-so ins) and late (atlei so ins) eiiergy '-31°» Went" 9“"t°Pm“‘ -i-i.rere is growing consensus
among acousticians that al-
Smge support (sTa..i,. Ratios belween ietiected and direct sound Early. ensemble hear-uig
stun) nieasuredon stage, reported separately rorearly i though many of these param-
(Z0—lO0 iris) and late (100-1,000 ins) energy '-file» mverbemnw dii Stage ere“ are useful, they do not
Dala from llie Intemntionnl Orgarlizaliorl forslariclarcllzaliori (1503009). provide a complete representa-
tion of concert hall acoustics. In
an interview with the author of
Eckirard Kaine (nersonai cornrniinicarion_ 2013) discussed this article, Pfeiffer (personal communication, 2018) noted
how the early design process differs outside the United States, theres a range ofperforrnance in any ofihe given Parameters
where project owners often hire independent acousticians to thats “CC9Pt3t3'1€i and "‘ 1’ “S9 thats hot h“t that the “"Ythi'
develop an “acoustic brief" and design rearns cornneie against cal holy grail of perfect acoustics does not exist. Acoustician
each other to develop a conceptual design that most effec- P3‘-tt SC3t't3't'°“Sh (P5750531C°mm“1'iiC3ti°1'i>2013) nfitfid Thai
tively responds to the acoustical goals outlined by die brief. standard parameters are particularly limited in describing
wig, such a Variety of oercennial factors and approaches to the spatial distribution of sound, saying we re not measur-
prioritizing them, it is no surprise that concert halls around mg the right things Y9t~ Bassuet (Personal C°mm“hiC3tt°h>
ine world sound as digereni frorn each odrer as drey do 2018) suggested that we should not be afraid to make con-
nections between emotional value and [new] acoustical met-
Haw can Perceptual snare be Thanarabad ‘1:;CS.SREC:l1'IIi’a\1't;\(IIlEtllI)l€S:l‘-6 su-nlliarlysritical rand Ll.l|.\§tl‘aIlV€d:
into Guanbitabiva, Measurable Data’? n can '3 a 6w _ an ‘gm’ °_w '3 our mumtfls an
. . . . . . Measurement Techniques Constrain Approaches to Concert
Considering a concert hall as a linear, tu'ne-invariant sys- _ in _ H
. Hall Design (Kirkegaard and Gulsrund, 2011) and Throw
tem, an u-npulse-response measurement can be used to A h S d d d L_ Y T E W k B __
understand how the room modifies the sounds of musical  at tan ar in mm‘ our W0 an or finer
instruments. Figure 2 shows impulse responses measured ( 0 JOB)‘
with an omnidirectional loudspeaker and two different mi- Deficiencies ofllxisting Ol1jeetl'vePurameters
crophones. The impulse response measured with an omni- In summary, the limitations are largely attributable to dif-
directional microphone (Figure 2, lefi), illustrates the direct ferences between an omnidirectional sound source and an
sound path from the loudspeaker to the microphone, early orchestra and between omnidirectional microphones and
reflections that are strong and distinct from each other and the human hearing system. As described in detail by Meyer
weaker late reflections that occur closely spaced in tune and (2009), each musical instrument has unique and frequency-
decay smoothly. Measurements are analyzed by octave band dependent radiation characteristics. As musicians vary their
Spring 2019 | Annuslzlcl Tnduy | 31

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