NY Times art. on concert hall acoustics
Josh Klein
A very interesting article:
http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
--
Josh Klein
Amherst College
HenryFogel
>From: Josh Klein jak...@unix.amherst.edu
>Date: 04/18/00 11:17 AM Central Daylight Time
>Message-id: <38fc...@amhnt2.amherst.edu>
>
>
>A very interesting article:
>
>http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
>
Yes but you can't get to it unless you register. Is this a recent article?
Could you summarize its key points?
Henry Fogel
Paul Kimoto
>> From: Josh Klein jak...@unix.amherst.edu
>> http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
> Yes but you can't get to it unless you register. Is this a recent article?
> Could you summarize its key points?
In today's (Tuesday) Science Times, this article by James Glanz is about
the use of scientific methods to design new halls, in particular, a concert
hall part of "Tokyo Opera City", and an opera house in Tokyo's (adjacent)
"New National Theater". The article says that these are good halls
(although I'd point out that _every_ new hall starts out with a good
acoustical reputation ...).
(In my *opinion*, registration with the NYT is not too onerous.)
--
Paul Kimoto <kim...@lightlink.com>
Mike Painter
> >
> >http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
> >
>
> Yes but you can't get to it unless you register. Is this a recent article?
> Could you summarize its key points?
Here it is from today's NY Times.
And to mollify the copyright police among us, I would point out that 17
USC 107 says that the fair use of copyrighted materials for purposes of
criticism, comment, teaching, research, etc. is not a infringement of
copyright. In determining whether the use is fair, the factors to be
considered are: the purpose and character of the use, including whether
such use is of a commercial nature or is for nonprofit educational
purposes; (2) the nature of the copyrighted work; (3) the amount and
substantiality of the portion used in relation to the copyrighted work as
a whole; and (4) the effect of the use upon the potential market for or
value of the copyrighted work.
Since this is posted to a newsgroup for comment, and it's not a commercial
venture, it's a newspaper article and there is will likely be little
effect on the Times's income from posting it, the fact that I'm posting
the entire article probably does not constitute an infringement.
cheers,
Mike
=====================
April 18, 2000
Art + Physics = Beautiful Music
Fine-Tuning a Hall to Hit the Right Notes Sound Reflection Analysis
By JAMES GLANZ
Can the sense of acoustic intimacy created by a fine concert hall be
measured in how many milliseconds it takes sound waves to ricochet from
the walls and balconies and reach a listener in the seats? Can a hall's
aural warmth be calculated from how efficiently bass notes rebound from
the same surfaces? Can the prized quality called resonance be estimated
from the rate at which the entire hall fades to silence after a blast of
electronic sound?
More to the point, can an architect rely on studies of these quantities,
using computer calculations and measurements in scale models, to ensure
that a structurally innovative, visually inspiring design for a new
concert hall will be an acoustical triumph rather than a disaster?
For years, the answer to all these questions seemed to be no -- the field
of concert hall acoustics has had only spotty success.
But now an unusually intense collaboration between architects and
acousticians has put the science of acoustics to the test, with two major
new successes in Tokyo.
The halls in question are the 1,632-seat concert hall of the multipurpose
complex called Tokyo Opera City, and the 1,810-seat opera house of the
adjacent New National Theater.
Both have architecturally daring designs, yet both have been praised by
musicians who have performed in them.
"This hall simply has some of the best acoustics in which I have ever had
the privilege to play," the cellist Yo-Yo Ma wrote in a commentary on the
concert hall that appeared recently in a technical journal. He said its
visual and acoustic aspects combined in a rare synthesis -- "a miracle,"
he called it.
Miracle or no, this is no small feat. "Going to the Moon is much simpler
as a physics problem," said William J. Cavanaugh, an acoustician at
Cavanaugh Tocci Associates who consults on both the construction and
restoration of concert halls. In a Moon shot, he said, "you've got one
source, you've got one trajectory that will get you there, and you've got
one 'listener,' or destination."
But in a concert hall, the trajectories of the sound waves begin at any
number of places on the stage, bounce in complicated ways from every
cornice and pillar, and reach their ultimate destinations in hundreds of
occupied seats.
The research for the new halls, whose principal architect was Takahiko
Yanagisawa, president of TAK Architects in Tokyo, may be the most
extensive use yet of acoustical measurements and calculations in efforts
to design concert halls that are not simply copies of great halls of the
past.
"If you make a copy of the old, great halls, you'll have a great hall,"
said Dr. Leo L. Beranek, an architectural acoustician in Cambridge, Mass.,
who was the principal acoustical consultant for the projects in Tokyo. But
the Tokyo concert halls, he said, "are different in appearance and they
have the sound of great halls."
The research is described in three papers, published earlier this year in
The Journal of the Acoustical Society of America, by Dr. Beranek and Dr.
Takayuki Hidaka, chief researcher of the Takenaka R & D Institute, which
conducted acoustical measurements and built models. The papers describe
how, as the designs took shape, scientists analyzed and worked to maintain
acoustical variables like reverberation time, spaciousness and intimacy,
each with a precise mathematical definition and musical meaning.
Without those studies, "you're gambling" on the acoustics, Dr. Beranek said.
Still, the success of two halls in Tokyo is unlikely to persuade all
critics that the science of concert hall acoustics has finally arrived.
There are still many acousticians who maintain that a knowledge of the
technical issues, while helpful, is less important than experience and a
repertoire of acoustically successful designs that one can fall back on in
a pinch.
"If you know your craft and you know your art," said Russell Johnson of
Artec Consultants, "the math today may not help you very much. And if you
believe some math that's wrong, you can get into trouble very quickly."
That cautionary note was echoed by Dr. Cyril M. Harris, a professor
emeritus of architecture and electrical engineering at Columbia
University. The purely technical approach "works much of the time, but
sometimes it doesn't, and you don't know the reason why," he said. "So you
get trapped. And you get real disasters."
Yet both Dr. Harris and Mr. Johnson acknowledged that recent advances in
acoustics could yield crucial clues to designers.
The history of concert hall acoustics is nothing if not contentious. No
single approach, whether based on science, experience, art or pure
intuition, has been without its heralded successes and unexplained
failures.
In a way, in fact, musical styles and performance venues have engaged in
what a biologist might call co-evolution, developing in ways that were
inextricably dependent on each other.
It is no coincidence that the unhurried, vowel-rich Gregorian chants sound
best in medieval cathedrals, whose "reverberation time" -- the time it
takes a burst of sound to fade away -- is 5 to 10 seconds. Later in
musical history, the polyphonic, highly articulated Baroque compositions
of Bach, Handel and Vivaldi benefited from being played in relatively
small rooms with hard, reflecting walls, in which the reverberation times
might be less than 1.5 seconds.
Those close walls also added a sense of acoustical intimacy. That is, the
delay between the arrival of sound directly from the instruments or
voices, and sound reflected off the walls and other surfaces is slight.
The smaller the delay, the greater the sense of intimacy.
Later still, as the Classical style of Haydn and Mozart gave way to the
Romantics, large concert halls with correspondingly longer reverberation
times were built to accommodate both the music and its growing audience.
Beethoven's later symphonies were composed "almost as though he
anticipated the large, reverberant halls that would be built in the next
half-century," Dr. Beranek wrote in his book "Concert and Opera Halls: How
They Sound" (Acoustical Society of America, 1996).
In another biological analogue, poor concert halls often did not survive
the wrecker's ball. In a kind of natural selection, the best halls of the
19th century were more likely to survive. The three halls most often cited
as models of sonorous pleasure are the Grosser Musikvereinssaal in Vienna
(built in 1870); the Concertgebouw in Amsterdam (1888), and Symphony Hall
in Boston (1900).
Each of those halls is roughly shoebox shaped, leading to quick
reflections from the fairly close side walls and balconies. Each has a
reverberation time of about two seconds. And each displays numerous
irregularities, like coffered ceilings and rows of buxom statues on its
interior walls. The diffusion of sound created by reflections from those
objects, acousticians agree, prevents a nasty acoustic "hardness" or
"glare" that smooth surfaces can generate. (This diffusion is one
characteristic that still awaits a precise mathematical definition, being
determined for now by visual inspection of the interior.)
Symphony Hall rates a special status in the field, since the person
generally regarded as the first to apply science to architectural
acoustics, the Harvard physicist Wallace Clement Sabine, consulted in its
design. Sabine had just discovered a crucial formula that relates a hall's
reverberation time to a hall's volume and the amount of sound-absorbing
material, like people and curtains, inside it.
"He really, literally, put the first numbers to this whole question," Mr.
Cavanaugh said. But reverberation time alone could not divide the good
halls from the bad ones. "Anybody that was working on it knew there was a
lot more to it than one number."
Dr. J. Christopher Jaffe of the Norwalk, Conn., firm Jaffe Holden
Scarbrough Acoustics, who also directs a program on sonics in architecture
at Rensselaer Polytechnic Institute in Troy, N.Y., said that a more
complete translation of the warm, rich sound of the great 19th-century
halls into scientific terms owed much to the development of fresh
acoustical measures, or "metrics," by Dr. Beranek.
"Leo got the Rosetta Stone to get that traditional sound developed into
reflecting patterns," Dr. Jaffe said. "That gave the architects some great
freedom."
That freedom, he said, is most useful for designs, like those of the new
halls in Tokyo, that do not carefully copy the tried-and-true,
shoebox-shaped halls.
Like intimacy and reverberation time, the additional metrics have
deceptively simple names like spaciousness, bass ratio, acoustical texture
and clarity. But each has a precise mathematical meaning that seeks to
isolate a specific aspect of acoustical quality in a hall. In the studies
leading up to the design of the new Tokyo halls, said Dr. Hidaka of the
Takenaka R & D Institute, measurements of those and other metrics were
made in 20 opera houses and 25 symphony halls in 14 different countries.
(While New York's Carnegie Hall is considered among the world's best, it
was not included in the study because there was no opportunity to make
acoustic measurements there, Dr. Beranek said.)
The idea, Dr. Hidaka said, was to get a quantitative measure of what made
the good halls good and the bad ones bad. For the studies, his team
generally produced a burst of sound from a 12-sided speaker on the stage
-- actually a dodecahedron with a small speaker on each face. Each burst
and its acoustic aftermath was recorded on tiny microphones placed in the
ears of dummies, and in some cases the ears of real people, scattered
around the seats.
The team worked out the value of the various metrics for each hall by
analyzing detailed forms of the sound waves picked up by the microphones.
Intimacy, for example, was defined as the time delay between the direct
arrival of the sound from the stage and that of the very first
reflections, which have presumably bounced off protruding side balconies.
Bass ratio gauges how efficiently low notes, compared with middle notes,
carom from the walls and other surfaces; a high bass ratio gives a hall
what musicians call warmth. Spaciousness is an estimate of what fraction
of all the sound bathing a listener has been reflected laterally, from
interior surfaces, as opposed to having arrived straight from the stage.
Dr. Beranek, Dr. Hidaka and their collaborators then compared those
measurements with an acoustic ranking of the halls based on a survey of
conductors and music critics. They found that the most beloved concert
halls had reverberation times near two seconds, intimacy times of not much
more than 20 milliseconds and relatively high bass ratios and spaciousness
factors. Other metrics also took on fairly consistent values in the best
halls.
Because of the need for greater clarity in understanding voices, the
optimum reverberation times for opera houses turned out to be shorter,
around 1.5 seconds.
Then the acousticians turned to large computers that had been programmed
to simulate the acoustics in the basic architectural designs of Mr.
Yanagisawa.
The team eventually built a 10-to-1 scale model of the proposed designs
and made just the same measurements, using tiny speakers, microphones, and
one-inch "heads" of dummy audience members, all scaled down in proportion
to the model.
Even the wavelengths of the sound in the model measurements were scaled down.
This work led to numerous adjustments in the original designs, including
changes in the height of the ceiling near the stage in the concert hall,
giving some of the balcony fronts a rakish, forward slant and adding a
special sound-diffusing material to the pyramidal ceiling.
The reflected wave patterns in the finished Tokyo Opera City concert hall,
wrote the team in one of its papers, "appear to be closest to those for
Boston Symphony Hall." Dr. Hidaka said acoustic data for the opera house
resembled those of the famed Vienna Staatsoper.
For all the apparent success of the Tokyo projects, Mr. Yanagisawa
emphasized that acoustical studies were far from the whole story. He
believes that his general immersion in the music of the great halls of the
world played as large a role in his understanding of good acoustics as the
results of the technical work did.
"I believe an excellent hall can only be realized by a design that
assimilates nuances beyond description by scientific data," Mr. Yanagisawa
said. "The final work is a world of sense created therefrom."
Copyright 2000 The New York Times Company
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Peter T. Daniels
> >A very interesting article:
> >
> >http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
> >
>
> Yes but you can't get to it unless you register. Is this a recent article?
> Could you summarize its key points?
> Henry Fogel
Registration is free and only needs to be done once; articles are available for only
one day.
--
Peter T. Daniels gram...@worldnet.att.net
Josh Klein
>>A very interesting article:
>>
>>http://www.nytimes.com/library/national/science/041800sci-concert-sound.html
>>
> Yes but you can't get to it unless you register. Is this a recent article?
> Could you summarize its key points?
> Henry Fogel
Yes, it's from today's (Tuesday's) Times.