Designing Mito, Part 4
Introduction to the Concert Hall ATM -- by Arata Isozaki
Quarterly Mito Geijutsu-kan No. 4, Summer 1989

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The Arena Format and Acoustics


This essay will introduce the Concert Hall ATM.

I have already been responsible for the design of two small halls: the Nova Hall in the Tsukuba Center Building, and the Casals Hall in Ochanomizu Square [Tokyo]. The first seats about 1,000 people, and the second around 500. Despite their difference in size, I based them both on the same rectangular concept. The rectangular hall used as the model for these two, it is fair to say, was the Musikvereinsaal in Vienna. While that hall has a capacity of a little less than 2,000 people, making it bigger than the ones I designed, it is said to have the best acoustics of any hall in the world.


While my design has taken clues from that, I decided to produce a different type [of concert hall] at Mito. Namely, I patterned its shape after that used by the Berlin Philharmonic: what is known as the "arena style." In Japan, the Suntory Hall approaches that style somewhat. Anyway, I used the arena as the basic shape of the Concert Hal ATM. With a capacity of 700 people, its size can be described as medium-to-small.

Halls seating less than 500 people are basically best for chamber music [performances], while those seating around 700 (as at Mito) can accommodate a small [chamber] orchestra. It would be more appropriate, then, to classify the Concert Hall ATM as a medium-sized hall rather than a small one. As regards the instrumental composition of ensembles performing there, a full orchestra would find it tight, while a small [chamber] orchestra would come out all right. Every group falling under the rubric of chamber music can be accommodated at the concert hall in Mito.

The layout of the concert hall is exactly like an opened-up hand. The stage corresponds to the middle of the palm, while the audience sits where the five stretched fingers would be. Seats have also been installed to the rear of the stage, usually for the listening audience but also for a chorus when necessary. Elements such as these make the Concert Hall ATM feel large, even though it is just a medium-sized one.

One distinctive feature of the concert hall is noticeable immediately upon entry: the three enormous pillars that are positioned a short distance from the walls. These three pillars, which support the whole weight of the large roof, are designed not to interfere with the audience seating. Returning to our hand metaphor, two of the pillars are located at the base of the fingers, while the third is directly behind the stage. As I said earlier, the whole weight of the roof rests on the pillars.

The center part of the roof, moreover, is capable of being raised or lowered as necessary. The basic reason for that is to change the hall's acoustics by altering the relationship between the volume of the air in the hall and the height of the ceiling. The part that moves is a disk attached to the ceiling, and rests above both the stage and the audience. Lowering the disk reduces the air volume in the hall, and conversely, raising it increases the air volume. Adjusting the height of the disk changes the acoustics for each instrument in fact, there are good and bad acoustic conditions [for each]. What I mean is that fine distinctions need to be made in the acoustics for [pieces or ensembles with] mainly strings (such as the violin), as well as for those with mainly percussion instruments (and the piano, which resembles percussion instruments more than strings). One of the main problems vexing concert halls down through time has been how to adjust for such differences smoothly. Various solutions have been attempted, including the development of variable acoustic devices, but most have ended up just being eyesores, and have not resolved the problem conclusively. Our attempt our response to that problem was to install a disk on the ceiling (i.e., a reflective disk above the stage), which can be raised or lowered so as to alter both the air volume and the angle of sound reflection, thereby changing the acoustic qualities of the room. That is the most distinctive characteristic of the Concert Hall ATM, acoustically speaking. The reflective acoustic disk is supported, then, by the three aforementioned pillars.

The problem of acoustics, in the final analysis, is one of reverberation. This reverberation adjustment device, I feel, is another new attempt characteristic of the concert hall at Mito. When the hall is finished, I am planning to have precise measurements made of the acoustics obtained with different instruments piano, percussion, or strings and then determine the proper height and angle [of the disk]. If that succeeds, I believe we can look forward to this hall's being different from any concert hall to date.

As for the stage, to use the hand metaphor again, its position corresponds to the palm of an open hand. By placing the stage in the middle of the hall (not the exact middle, obviously, but shifted back a little), everyone sitting around it is able to look down upon it. I employed this type of stage commonly known as the arena type for the concert hall in an attempt to minimize the viewing distance (the distance between the audience and the stage), just as I did in the ACM Theatre. Simultaneously, in the case of the concert hall, it is important to ensure rich acoustics, which necessitates a consideration not only of the direct sound but also the way secondary and tertiary reverberations overlap. Slight lags in the time of sound transmission enhance the richness of the sound by adding to it the richness of reverberation. Acoustically, I am determined to emphasize that point more than anything in the Concert Hall ATM.


The Pleasure of Presence


The audience seating is basically divided into five sections. Three of the sections are contained in the parquet (pit) section on the main floor, and the balconies on either side constitute the other two sections. Altogether, then, the five sections correspond to the five fingers of the hand opened up. Two of the pillars are sort of tucked between the bases of the fingers, while the other one is behind the stage. That is the layout of the seating area.

The reason I adopted this format for the seating was to separate the audience into groups, allowing them not only to see the stage but also each other (albeit at a slightly different angle of vision). The main distinguishing feature of the arena type of concert hall is this: to impart a sense of unity to the audience and the stage namely, producing a single, busy space. That is the point I wish particularly to stress [in my design].

"Why do that?", you might ask. Well, when I built the Casals Hall [in Tokyo], for instance, one thing I sensed was that the only thing the audience views in square, boxlike halls is what is in front of them. Aside from that, they might be able to get a partial view of the balconies on either side. Those sitting in the balcony, on the other hand, have a pretty good vista of the whole situation in the concert hall, but the people down below only get a view in one direction, seeing nothing but the stage. That means that they get no sense at all of the atmosphere or ambience around them. While a one-on-one relationship is established between the sound source (the performance) and the audience, there is no feeling of the triangular relationship between different sections of the audience as well as between the audience and the stage. That situation leads to an extreme sense of loneliness.

I suppose that if one pursues the sound source vs. listener relationship to its logical conclusion (I exaggerate here), one winds up with a "Walkman" situation. That is, since it is good enough simply to pit the sound source against the listener, the closer the two are together, the better. In that case, why not just put the sound source next to the ear? The eye does not need to see anything. If so, and granted the existence of the one-on-one relationship [between the sound source and the listener], you logically end up with the "Walkman" situation, so it does not matter where you are [when you listen to music] as long as the technical conditions are satisfied. In certain cases, that would mean not even needing to go to a concert hall at all.

That being so, why bring yourself to a concert hall to hear a performance in the first place? One answer to that, of course, would be to hear a performance live, but even more than that, it is to experience the sense of presence or "ambience" of the place. Being in a certain place, along with other people, learning such things as how large the audience is that day, and listening to the music all these things combine to produce the ambience that is detectable as a spatial characteristic, going beyond the simple functional act of listening to the music. In addition, the experience is influenced by one's visual appreciation of the design of the hall. Such relationships build upon each other, giving significance to the act of going to the concert hall, I believe.

Though I pride myself on having designed boxlike concert halls in the past that have ended up being quite good acoustically, one of the reasons I decided to push the idea [of an arena-type hall] forward at Mito was the element of ambience. I thought that people would want to go to this concert hall middling in size though it is if they thought that they could get a sense of the ambience. Otherwise, they might decide that listening to the stereo at home might give them better sound in some cases. But I felt somehow that it was important for the concert hall at Mito to be able to impart [the audience] with some additional meaning [in their experience], and that's why I went ahead with the open-hand-shaped design.

To put it extremely, it is the three pillars standing in the middle of the concert hall that give it significance. As the pillars are meant to be symbolic, some people looking at the plan of the hall might think they are in the way. Well, considering that the location of the pillars is such that they inspire a debate whether or not they are in the way, I believe, conversely speaking, that they in fact serve to reiterate the symbolism of the space.

As for the ceiling, also, not only is it characterized by the central disk that moves up and down, but also by the small arches that support the disk along its rim. In architectural terminology, these are called "pendentives" [triangular sections of vaulting between the rim of a dome and each adjacent pair of the arches that support it]. The roof takes shape in between the pendentives. The ceiling can be also be made to assume various shapes, such as by having the lighting come out from the pendentives. As for myself, I feel that [this ceiling] enables me to take my previous experiences one step further.

Recordings and Rehearsals

One of the most important points of consideration in [designing] a concert hall is how to keep extraneous noise from entering. Besides preventing unwanted noise coming in from outside the hall, one must also hold down the noise generated by the air conditioning and other such things. From my previous experience in designing halls, I believe that I will be able to reduce the noise substantially at Mito as well. When I say "reduce," I mean that the noise can be cut [completely], allowing the hall to be used as a recording studio as well.

Unless a recording is live, however, most studio recordings today tend to eliminate spatial reverberations and echoes totally; instead, they first make a direct recording of the instruments, after which the other elements are mixed in on the record or tape. Although little regard was made in the past on recording the sound emerging from the acoustics of a certain hall, there is now a renewed recognition of recording live performances in concert halls. Whereas the old way of recording such performances unavoidably used to create a mechanical sound, there are an increasing number of records highlighting the various influences stemming from the distinctive characteristics of a particular hall. Just because a performance is recorded live does not mean it needs to include all the audience noises the applause and the clamor but it can be done just as well without the audience. That makes a difference. I wanted to lift the standards of the concert hall at Mito to the level at which such [recordings] could be done: namely, securing a sound insulation level sufficient to cut out all extraneous noise, thereby permitting recordings to be carried out. If those conditions can be met, it will be possible to produce records that convey the hall's acoustics. And that was one of the goals for the hall that I definitely wanted to realize.

After all, seeing how far videos and records have advanced today, especially in the case of music, most people probably feel that they do not need to go to concert halls anymore. They have even stopped going to the cinema, though I think there are advantages of watching movies there: namely, seeing the picture on the big screen. The same thing can be said for music as well, and even more so. By being able to feel the sense of ambience or presence, the experience goes beyond merely having [the audience] hear the sound functionally and feeling satisfaction thereby it also involves the addition of several other factors. Since that feeling is sort of a "memento" of having gone through the trouble of visiting the concert hall, I have to design the sort of concert hall that permits or produces it. In that respect, as I mentioned earlier, since I have arranged the audience seating in a way that allows people to look at each other (or at least to sense the possibility), I believe that they can feel an even greater sense of the ambience. I want to succeed in imparting that sense by all means, since the meaning of the space would be lost otherwise.

The lobby of the Concert Hall ATM has been given a dual function: it also serves as the site of the permanent collection for the Contemporary Art Gallery. During intermissions, then, the audience can take a break by going to the coffeehouse as well as by enjoying the collection.

There is also one more room [in the concert hall section of the ATM complex] the rehearsal room which has been designed acoustically so as not to let sound affect other rooms. Specifically, it has been designed to be completely "floating," that is, its wall and ceiling are completely separated from the surrounding. Situated in the basement, the room is the same size as the concert hall.

The reason I chose that design is that to be thoroughly sure that the music being practiced in the rehearsal would in no way filter through into the main hall and be heard there. From the rumors I hear about other concert halls, it is pointed out that plenty of them have committed the elementary mistake of not ensuring complete sound insulation, meaning that no rehearsals can take place in the rehearsal room while a concert is going on in the main hall. Since I did not want to follow in the footsteps of those halls, I designed the rehearsal room this way.

Two other small rehearsal rooms have been provided, one of which can be used for recording playing the role of a complete recording studio. The other room, which is medium-sized, has been included for the use of any orchestra that may be based in the concert hall in the future. At minimum, I felt that such facilities should be included for that purpose.



World-class Organ Hall


Let me last introduce the organ hall (i.e., the entrance hall). Everyone must pass through this hall as they enter the ATM complex, whether from the road or the plaza. By making its ceiling high, I have given it the proportions of a European church. A pipe organ has been installed on the second floor.

The hall represents two different meanings. First, while it normally serves as an entrance hall, it can be closed off and serve also as an organ hall in the pure sense, separated from the rest. Furthermore, the organ can be playing in the background even when there is no official concert, just like European churches, where someone may be practicing or performing at any given time. The organ hall thus has two purposes: pure concert performances, and background music. My plan is to let both kinds of organ sound be heard here.

Some may ask why I decided to put the organ here, when common sense and tradition would call for placing a concert organ in the main concert hall. There is a good reason why I didn't, and that is the problem of reverberation time. Since the acoustics of pipe organs evolved within the context of church music in Europe, one special feature of organs is that they have been designed with the extremely long reverberations of churches in mind.

To be more specific, considering that the reverberation time in many churches is five to seven seconds (or even longer), one can actually conclude that the most natural sound for an organ the most "organ-like" sound is the organ sound that can be heard in churches. On the other hand, it is very difficult to secure that kind of reverberation time in regular concert halls. If a piece calls for the use of percussion, a five-to-seven-second reverberation time would be much too long, making it hard to hear anything else. For that reason, most concert halls have compromised by cutting the organ reverberation, fitting the organ to meet the hall's specifications. After a while, however, the organs compromised in such fashion don't even bear listening to anymore. Most of them sound somehow lifeless they just sound bad and lack in what one expects from a true organ. To cover up for such defects, various things have been invented, such as devices that electrically amplify only the organ sound and nothing else. Though I had considered using such methods, I decided that since they were, after all, mere makeshifts, they generally should not to be used (although perhaps unavoidable in certain cases).

Because I feel that the organ ought to be played in rooms specially designed to accommodate it, I "expelled" it from the concert hall, and gave it its own room. Specifically, given that the entrance hall was shaped like the space of a church, I put the organ there, since I felt that it could be adapted thoroughly to bring out the best in organ acoustics. Its reverberation time is about five seconds, as opposed to 1.6 seconds or so in the main hall. Clearly the two are different in terms of reverberation time. I hope that the entrance hall can always be used for organ concert (maybe "always" is overstating it, but at least occasionally).

Although the entrance hall may not offer a perfect performance environment, with people walking through and murmuring, the same situation is found in churches when someone is practicing the organ and other people walk in. I thought that the organ could serve the purpose of background music if someone was practicing on it, so that's why I went ahead and put it there. While the entrance hall might be a bit noisy at other times, given the way that sounds will echo, that fact can be seen, conversely, as proof of how good the acoustics are. I think it will offer a different impression.



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