ADDENDUM TO “ACOUSTICS”
©1982 Mark B. Anstendig
THE DIFFERENCE BETWEEN DESIGNING AND CORRECTING A CONCERT HALL
There is a big difference between designing a concert hall from scratch, with either a good or bad acoustic, and correcting an already existing acoustic. Totally different skills are involved: the first demands a knowledge of design principles; the second demands a particular, very rare type of trained hearing capacity. It does not follow that someone with the first skill has to have the second. Even a musician, trained to recognize notes and nuances, will not necessarily have the needed capacity to recognize the various frequency ranges without special training. I can attest to that myself: after many years with the finest ear-training teachers in the world, I had to learn a completely new manner of hearing. ONE CANNOT RECOGNIZE SOMETHING THAT ONE IS NOT FAMILIAR WITH. Therefore, an ear that can dependably recognize faults in equalization can only be developed through the use of modern equalizers and analyzers capable of isolating the various sections of the frequency range so that the student can learn to identify them by hearing them separately. This is an important reason for the confusion in the field of acoustics, because the faults one hears usually have their causes in a different range of frequencies than the range where one finds fault and the means of training oneself to hear this are a very recent addition to technology. The most famous German hi-fi demonstration record of the sixties, using the fourth movement of the Klemperer recording of the Berlioz Fantastic Symphony, demonstrated how each segment of the frequency range sounded by itself. While the performance continued, it first reduced the frequency range to only the middle frequencies and then, one by one, as the movement progressed, each octave above and below was added, until the full range was restored. Now, by using frequency equalizers when playing back recordings, this process can be duplicated for learning purposes.
HOW FAULTY STEREO TECHNIOUES HAVE INFLUENCED ACOUSTICS
whoever is “correcting” Davies Hall has a particular, faulty sound-image in
mind that he is unwilling to abandon. It seems to come from listening to
unequalized stereo sound reproduction and from controversial stereo techniques
that supposedly introduce spatial effects, such as using sound delay circuitry
to add reverberation: the hall's acoustic exhibits the anomalies that these
devices introduce into sound reproduction and the idea, which is an
impossibility, of changing the reverberation retimed in the hall, derives from
the fact that these devices operate by adding a second signal, which is
actually a repeat of the original signal that is played a certain amount of
time after the first signal is produced. The amount of time that the second
signal follows the first can be varied by the machine. But this has nothing to
do with acoustics, wherein reverberation time is an absolute that is determined
by the distances the sound travels in the room. Further, the reverberated sound
in a hall is very different in character from the directly radiated sound (the
overtone construction is changed and some of the delicacy of nuance is lost)
and is not simply a repeat of the sound as it comes out of the instruments.
Unfortunately, in sound reproduction, these effects act in a manner similar to
the malfunctioning automatic focusing device described briefly in our paper on
television quality (available upon request from The Anstendig Institute). In the
presence of picture noise (interference), that device de-tuned the set until
the whole picture was so diffused that the noise was no longer noticeable. But
the picture itself was also diffused. The set should have been tuned to the
most precise setting, and the interference eliminated by a technician. That
particular AFT-device simply leaves the defect there and smears it over. (There
was a famous incident in
Even stereo itself is by no means uncontroversial, is not necessary to a complete listening experience, and does not reproduce the effect of a good concert hall. As a way of reproducing directional effects, it is a compromise that employs the simplest, cheapest means of doing so (only two signals), and is therefore totally limited in the spatial effects it can achieve. (Another paper, “STEREO: A MISUNDERSTANDING”, available from The Anstendig Institute, deals in detail with stereophony.) In a good hall, one does not hear directionally; one hears a perfect blend of well mixed sound. In most of the great compositions, the composers expended great efforts creating sound colors by blending and fusing the sounds of various instruments into one conglomerate, mixed sound. The fact that the instruments had to be spread out on a stage was a matter of necessity. From the composer's point of view, the ideal would have been if all the sounds could emanate from the same point, since they were meant to fuse, not to be pulled apart, as is the case in much stereo recording. After 15 years in the finest conducting classes, I can attest that the best teachers spent much time and effort teaching us to achieve a type of perfectly balanced blending of instruments that much stereo destroys. One can flip the switch to mono when listening to music and have no difficulty hearing the different instruments if the sound is correctly equalized. But that can only apply to performances wherein the conductor had balanced the orchestra in the first place. The proof of this is in the finest piano playing, wherein perfect balance of the dynamics of the separate notes and voices clarifies the textures without the slightest directional effect. Stereo demands that we buy double everything, so the manufacturing and recording world is not in any hurry to clarify the shortcomings of the medium, most sound technicians are dependent on the industry, and the artists are dependent on...there is no need to elaborate.
THE "IMPROVEMENTS" IN DAVIES HALL
The latest attempts to "improve" the acoustics of Davies Hall are examples of the confusion and misunderstandings that our papers dealing with sound, hearing, and acoustics are meant to clarify:
Our paper “Acoustics” explains the fallacies in the use of reflectors to improve a hall's acoustics and clarifies current misunderstandings about reverberation and reverberation time:
CARPETING THE HALL AND USING REFLECTORS ARE SELF-CANCELING PROCEDURES: THE CARPET REDUCES REVERBERATION AND THE REFLECTORS ADD TO IT.
In this case, if the intention were to reduce reverberation, the floor, being the most shielded reflecting surface, was the least effective, and riskiest, place to begin. The first step should have been to experimentally hang the walls with removable sound-absorbing material, which could be much more easily removed than an expensive carpet which cannot be touted as an appropriate corrective procedure when the walls are obviously the place to begin if the intention is to reduce reverberation.
There is no need to repeat the reasons why the use of reflectors to improve the disbursement of the sound to the audience is plainly and simply a mistake, as it is fully explained in the paper “Acoustics”. One thing more should be pointed out here: the word "reflector" is a misnomer that does not describe the devices used in Davies Hall. "Diffuser” is more accurate. The word reflector implies a flat, or concave surface capable of precisely focusing and reflecting vibrations. The convex surfaces of the Davies Hall reflectors do no such thing. They diffuse the sound, radiating it indiscriminately in an unfocused manner.
A DESIGN THAT NEEDS REFLECTORS IS A FAULTY DESIGN
In relation to the discussion of the Berlin Philharmonic Hall in “Acoustics”, it should be made clear that the Berlin Philarmonic Hall was designed to work WITHOUT reflectors and that the design, though a genial concept, was not wholly successful acoustically. Reflectors were only considered AFTER the hall was finished and originally were for the sole purpose of helping the orchestra hear itself better, not for the purpose of better sound disbursement. To incorporate a need for reflectors into the original design concept, as was the case in Davies Hall and the two new halls in Toronto and Baltimore by the same acoustician, is tantamount to designing corrections into an acoustic that one already knows will be faulty. A hall with a good acoustic does not need reflectors! If reflectors are considered necessary when the hall is in the design stage, the design is faulty and should be changed.
In halls with flawed acoustics, it is often remarked that the best place to sit is in the balcony. This can very well be the case, for two reasons: 1) Since sound becomes softer in relation to the square of the distance it travels, the volume level is usually substantially lower in the balcony and our hearing is more tolerant to distortions, particularly those in the balance of frequencies, at lower volume levels. 2) The balcony receives less of the reverberated sound: it is not affected by the sound reflected off the walls below it, while the sound reflected from the ceiling reaches the balcony at essentially the same time as the direct sound, with the ceiling acting more as a conductor than as a reflector. Also, the time difference between the arrival of the direct sound and that of the reflected sound is smaller.
A problem inherent in correcting bad acoustics in already existing halls is that of obtaining knowledgeable opinion from experts who have absolutely no reason to say anything but the unadorned truth. Almost everyone who is active in the musical and acoustics world is dependent on some person or other who would find the truth uncomfortable and experts themselves are notoriously unhappy about admitting when they are wrong.
It is so very important to remember that, with Davies Hall and any other acoustic situation, WE ARE DEALING WITH UNCHANGING ABSOLUTES THAT ARE THERE FOR EVERYONE TO HEAR. Until a hall itself is physically changed, the sound of that hall remains an unchanging constant; it is people who not only hear differently, but whose hearing, far from remaining constant, changes even during the course of a concert. (Please refer to our paper on equalization.) But that does not mean that the character of a hall's acoustic is a matter of opinion, as is usually claimed; it means that most people are either unable to hear and evaluate it or unaware of what to listen for.
THE PURPOSE OF HIGHER MUSICAL EXPERIENCE
The first step for anyone interested in comprehending the problems of acoustics is to understand exactly what should be achieved through higher musical experience.
THE OBJECT OF THE PURSUIT OF CLASSICAL MUSIC, EITHER BY ITSELF OR IN COMBINATION WITH OTHER ARTS, IS TO ACHIEVE THE FINEST, MOST EXQUISITE EXPERIENCES THAT THE HUMAN BODY IS CAPABLE OF SUSTAINING.
Music is the highest, most powerful, most overriding of all the arts. In the presence of music, all the other arts take on the character of the music, not vice versa, and it is capable of, and can produce in us, the finest, most delicate of possible human reactions. If the experiential phenomena produced by the musicians and in the bodies of the listeners were translated into scientific, physical measurements (evenness; the minute differences in volume that produce the expressive content; the mechanical precision in the coordination of the orchestra players' bodies; and the minute vibrations of the listeners' bodies and ear drums) those measurements would equal, and in many ways surpass, anything possible in any field of science or engineering. A sensitive, well trained human being, in a correctly relaxed and balanced physical state, is capable of more extraordinarily fine differentiation than any machines or measuring instruments available to science, including realms of phenomena that science has no means of measuring. It should therefore be clear that ANY DISTURBING FACTORS, HOWEVER SLIGHT, CAN DEGRADE A FINE MUSICAL EXPERIENCE. The irritations, tensions, and distractions of an acoustic like that of Davies Hall make such a fine musical experience as described above impossible without the performer resorting to extra-musical measures that militate against his interpretive intentions. Even trained musicians have limited consciousnesses and can only simultaneously concentrate on a limited number of things. Music-making alone takes up anyone's full concentration, and a need for the musicians to be constantly adjusting their playing in an unnatural manner makes them technically uncomfortable, limits the quality of their interpretation, and destroys the natural flow of a performance. This is the reason that concerts in Davies Hall by even the finest orchestras, such as the Amsterdam Concertgebau Orchestra, have more than a usual share of missed or cracked notes. The only concert I have heard in Davies Hall that achieved the exquisitely refined type of experience that I am used to was that of Claudio Arrau. But he had to achieve it by trimming the dynamic levels of his playing, reducing the amount of pedal, and even making a quick, unexplained program change because there was nothing he could have done to achieve the necessary clarity that his well-known interpretation of the Beethoven Waldstein Sonata demands. What a depressing situation it is for the members of an orchestra to know that there is little hope for those kinds of magical performances that they are striving for to happen. The orchestra members may not dare to openly complain: but they know better than anyone that the bad acoustic makes it impossible to achieve their potential. A moment's contemplation of their plight should convey to anyone the seriousness of such a situation.
Two things Jean Morel constantly impressed on all of his conducting students during my five years as his student at the Juilliard School of Music are the best directives for proceeding with correcting the acoustics of any hall: In teaching us how to arrive at the expressive content of music as the composer intended it, he used the analogy “first you wash your face; then you put on your makeup", and he never stopped emphasizing that "you serve your art; it does not serve you”.
FIRST YOU WASH YOUR FACE; THEN YOU PUT ON YOUR MAKE-UP
Pursuing that metaphor in relation to correcting the Davies Hall acoustic, the reflectors are simply make-up that smears the dirt around more or less evenly without getting rid of it. First wash the hall's face, by correcting the acoustic without the use of reflectors, baffles or any other extraneous devices. Then one can experiment with external devices, since one can always return to a basic good sound. But to begin with that type of experimentation before establishing the best shape and resonating characteristics of those basic components that determine the acoustic (the walls, floors, ceilings, stage, and their reflecting characteristics) is absurd.
YOU SERVE YOUR ART: IT DOES NOT SERVE YOU
The second quote, which is The Anstendig Institute's guiding principle in making these papers available, has vast implications both for correcting Davies Hall and against using any hall until it is acoustically correct. Until then, it does not serve art; it degrades art. Since stopping the use of most halls is unthinkable, no stone should be left unturned in the efforts to correct them without delay.
The Anstendig Institute is a non-profit, tax-exempt, research institute that was founded to investigate stress-producing vibrational influences in our lives and to pursue research in the fields of sight and sound; to provide material designed to help the public become aware of and understand stressful vibrational influences; to instruct the public in how to improve the quality of those influences in their lives; and to provide the research and explanations that are necessary for an understanding of how we see and hear.