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Do Acoustics Matter?
Internationally-Known Recording Artist
Pianist in Residence, California Institute of Technology, 1974-2004
Founder-Director, Caltech Music Lab, 1979-2004
Lecturer in Music in Electrical Engineering, Caltech, 1979-2005
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Or should it be, "Does acoustics matter?" This is just the first of many awkward points in this subject. If you are building a new auditorium or renovating an old one, the information here may help you to deal with a few of the awkward things. What's here are three memos I wrote to fellow members of the Restore Bailey Hall! Committee, set up to advise on the renovation of the old auditorium of a Los Angeles public high school. (The name "Bailey" is fictitious.)
The first memo says why quietness and good acoustics are important; the second discusses recording of events; and the last covers two specific aspects of acoustics. In each, I've tried to show what's at stake as vividly as possible; for instance, by imagining remarks which might come from performers and audience. (For more, see my article for Harvard Magazine, "Audiences of the World, Arise!. For a primer of acoustics for the general reader, read "Annals of Architecture: A Better Sound," by Bruce Bliven, Jr., The New Yorker, Nov. 8, 1976.)
Some things seem clear:
- Yes, good acoustics do matter. "Auditorium" means a place for listening. If it isn't good for listening, why are we spending the money and time?
- Computer technology now permits us to hearvia computer-controlled loudspeakersthe way the hall will sound, before it's built. (Not perfectly, but to a useful degree.) This would have been regarded as magic a generation ago; and it's valuable because it helps a committee come to agreement quicker and with more confidence.
- An acoustical consultant ("acoustician") must be involved from the first moment of the project.
- In case of disagreement between architect and acoustician, the contracts should give priority to the acousticianif you want to get a good hall.
- The legal doctrine of "substantial performance" may prevent your getting what you specify unless you take steps to incorporate performance standards and penalties into the contracts. You may want the contract to say that the specified performance is "of the essence of this contract." (I'm not an attorney! Consult an attorney experienced in construction law!)
I'm not an acoustical consultant, either. What I am is a concert pianist; and through my career, I've seen that people love attending events in acoustically good halls. This should come as no surprise: Performances reach our hearts and minds via our ears. A fine auditorium inspires performers to give their best, provides the closest communication between performers and audience, assures that audiences receive the maximum of enjoyment and understanding, and attracts additional events to the venue. Yet for some reason, it's rare for individuals or a committee to choose to make a fine hall.
You can be the exception. Make decisions that are acoustically beneficial, see that engineering and construction are carried out properly, and the fine acoustics will be your good deed, your legacy, to current and future performers and listeners and your whole community.
Memo 1: Quietness and good acoustics
Several people have suggested that since Bailey hall is not going to end up perfectly quiet, it isn't worth it to make it quieter than it is now. And since the acoustics won't be perfect, it's not worth making them better. In this memo, I say why I think every little bit counts. (Skip to section VII for the "meat.")
Good acoustics are what bring the audience the full beauty of the sound produced by actor or musician, and enhance that sound with the "bloom" of the hall's reverberation. (This bloom is very noticeable in Bailey.) Good acoustics also give the performer a full sense of the sound, so that he or she, actor or musician, can control it for greatest expressiveness.
Quietness allows the audience to hear the finest details without straining. This is important because details of sound communicate details of feeling. Also, because a quiet hall makes soft sounds more audible, the performer can produce a wider "dynamic range"the range from softest to loudestwithout having to make the loudest sounds impossibly loud and therefore ugly. This wider range makes performances more expressive, for dynamics are one of the prime carriers of emotion.
Acoustical quality involves questions like:
- How much reverberation does the hall have, and what is its character?
- Does it last long enough to support the sound, so the performer benefits from the "bloom" and doesn't feel he or she is working into cotton wool?
- Does it last about the same amount of time for all pitches, or do some last longer than others, which can sound weird?
- Does it die away smoothly (good), or does it have distinct echoes (bad)?
- What about the power of the sound? Is it carried fully to the audience, or lost in wings or fly-gallery, or absorbed by walls or shell that are too floppy?
Quietness means the obvious thing: How much noise is audible in the hall? But one can also ask, What is the character of the noise?
- Is it a low-pitched hum, which will cover the voices of some actors and the sound of bass and baritone singers, cellos, double-basses, tubas and trombones?
- Is it higher-pitched, where it will interfere with other actors, and with sopranos, altos or tenors, violins, violas, flutes and clarinets?
- Does it have a pitch, which will become a dissonant note in every moment of performance? (Every vent fan and every motor makes noise with a distinct pitchlisten to your refrigeratorwhich is why their noises must be carefully isolated.)
- Is it a smooth continuous wash of sound, which may be relatively unnoticed? Or a succession of noises like a jack-hammer, which cannot be ignored?
- Is it always present, like air-conditioning in hot weather, or occasional, like a toilet flushing?
- Is it produced inside the hall (fans) or outside (airplanes, motorcycles)?
A hall could be utterly quiet and yet have lousy acoustics. Or it can be noisy and have great acoustics, though this is harder to imagine, because how would you hear the great acoustics through the noise? Still, it's useful to separate these two things. Noise is one; acoustics is another. What you do to improve either one has basically nothing to do with the other. Bailey Hall, according to the measurements, is noisy! Yet the acoustics are promising. I wonder if it doesn't have the possibility of being, overall, the best hall in Los Angeles, at least for seats in the balcony and the front of the orchestra section. This is why it's so worthwhile to improve the acoustics further and make the hall really quiet.
Who will benefit if noise is reduced and acoustics improved? Everybody on stage and off, in every performance and every rehearsal. But the ones most in my mind are the students, our children. As a performer, I know how much their experienceand their educationwill be enhanced by having Bailey Hall be more nearly what it can be.
- In a quiet hall with good acoustics, hesitant voices and instruments will still be heard. The quietness will let them be heard; and the acoustics will improve them. The students will come out from the experience saying, "I can't wait to perform again!" Parents will say, "My daughter sounded better than at home!"
- In a hall with good acoustics, a normal loud sound from the stage will come across as loud to the audience, with no need for strain by actor, singer or instrumentalist, and thus no risk of ugly tone. The full power of the sound will be conveyed by the acoustics. Students will say, "I filled the hall with my sound!" Parents will say, "My son sounded like a pro!"
In these days of amplified sound, we forget that real voices and instruments can only play so loud and no louder. And we forget how lovely is the sound of natural voices and instruments, because we are so used to the corruption of amplification. (All amplification corrupts tone quality.)
- A quiet hall widens the "dynamic range" of performancesthe range from loudest to softest. This communicates a wider range of emotion because in performance, as in everyday life, louds and softs are directly related to feeling. Students will say, "I really got into the feelings!" Parents will say, "They really communicated the feelings!"
- The quieter the hall, the lower the audience's stress level, and the more welcoming listeners will be toward the performance. Students will say, "The audience were such good listeners!" Parents will say, "I even enjoyed listening to other people's kids!"
Who will suffer if Bailey's noise is not reduced and acoustics not improved? Everybody on stage and in the audience, in every performance and every rehearsal. But the ones most in my mind are the students, our children. In a hall that's noisy or has bad acoustics, the performance is harder to hear, and the expressive points tend to be lost. Soft partswhether spoken, sung or playedare less audible, so fine details of feeling are less clear. Loud parts don't come across as loud, so the feeling they convey is lost, too. Noises inside and outside the hall distract the audience's attention. Student performers will say, "What was the point of all the preparation? I couldn't put it across!" Parents will say, "I guess my child isn't as good as I thought. And come to think of it, none of the kids sounded good."
Some have pointed out that even if the hall were utterly silent in terms of internal noise, there would still be noise from outside. This is true. However...
- Outside noise will be much reduced when the room is finished, because many openings will be properly sealed.
- When you're in a big quiet spacefor instance, a churchthere's a wonderful "distancing" of outside noise. Psychologically, even when you hear it, it doesn't bother you nearly so much, because of the interior quietness of the space.
Memo 2: Recording in Bailey Hall
This memo deals with recording in Bailey, and touches on sound reinforcement.
Campus performing organizations seem to use recordings for multiple purposes:
- To confirm group identities,
- Increase student self-esteeem,
- Raise money, and
- Give feedback to performers from concerts and rehearsals.
This last is a powerful tool for learning; see my book, To Hear Ourselves As Others Hear Us.
In addition to theatrical and musical performances, there must be talks, convocations, etc. which people will want to record.
It's been suggested by a contractor that events be recorded by hiring for each occasion an engineer who will "pull up a van." This costs $700-1000 per event (Los Angeles prices as of year 2000). This is a lot of money, so it would seem sensible to have a permanent set-up. At least it would be nice to be able to make a decent-quality DAT (digital audio tape) on a routine basis. This requires:
- A control room. If it's well-enough isolated from the hall, then speakers could be used for monitoring; otherwise headphones. (Speakers are preferable.)
- Built-in conduits for microphone cables from stage to booth, and from hanging-microphone positions to booth. The conduits will begin in boxes where microphones can be plugged in, and these should be provided at numerous locations. Picking up the sound of full orchestra or band requires mikes to be back from the front of the ensemble. This may put them over the audience, where a stand would be awkward to use and would make whole groups of seats unusable. Sound Reinforcement requires at least one major conduit from the booth to a control location amid the audience. It makes sense for this conduit to be installed with the others. These conduits should be installed now!
- Recording equipment: Microphones, recorder(s), amplifiers, speakers, headphones, etc. Need not be bought now.
The expenditure involved is not trivial, but those $700-$1000 figures for hiring an "on-location" engineer each time aren't cheap, either.
Memo 3: Flutter Echo & "Envelopment"
While we wait to see the plans for angled side-wall panels being designed by the acousticians, here's my understanding of what the panels will accomplish? They will do two things: eliminate an acoustic defect ("flutter echo") and add an acoustic virtue ("envelopment"). Both are necessary.
- Eliminate or reduce "flutter echo." If you hold your hands above your head in Bailey and clap once, you will hear a long string of distinct echoes dying away. That's the "flutter echo." It is created partly by the parallel side walls, and will be eliminated or reduced by putting angled panels on the walls. Why does it matter? Because speech and music are full of sounds like hand-claps, and every one of them is followed by a string of echoes which confuses the sound. Speech consonants like "t," "d" and "k," for example; and in instrumental music, every "attack," that is, the beginning of every note on every instrument. Flutter echo turns every attack into a multiple beginning, blunting the music's rhythm; and corrupts the "rests," the musical silences, with strings of echoes. Trying to fix the problem by amplifying the sound does not work. It just makes everything louder, including the echoes, with the result that listening is more fatiguing. (Amplification has its place. This isn't it.)
- Add "envelopment" to the sound. No matter what hall you're in, the first instant of each note comes from the performer to you in a straight line (because that's the shortest distance). Any sound that bounces off the ceiling, walls or other surface, follows a longer path and therefore arrives later. Saying this another way, the first sound you hear on each note is completely *unaffected* by the hall. For that one instant, there's no difference between being in Bailey, being in an airport terminal, or being outdoors (ignoring background noise). After that instant is when the hall makes its contribution. And the beginning of that contributionthe first tenth of a second or sois when reflections from all over the hall ought to give you the sense the experts call "envelopment," the sense of being "enveloped" in the sound. This is one thing people treasure about a fine hall. According to the acousticians and my ears, Bailey is weak in envelopment. You feel as though the sound is all coming from the stage. That's not the way it's supposed to be. You're supposed to be able to tell where it's coming from, of course, but you're also supposed to feel that you are *in* the sound. This acoustical behavior of a fine hall helps generate the psychological feeling of participation in the event. For good "envelopment," the reflections arriving at your ears in the tenth of a second after the direct sound should come from as many different angles as possible. This is what lets your ears and brain know about the hall you're in; and this is what Bailey does not give you, because the flat, parallel side walls "ping-pong" their reflections above the audience instead of angling the sound to listeners' ears. Thus a major improvement will come from carefully varying the angles of the side-wall panels. With better envelopment, students and other performers will say, "I could really tell how I was coming across." Parents and other listeners will say, "I felt much more involved in the performance."
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