Title means "Quietness", "Comfortable Sound" and "Excellent Acoustics"

Nagata Acoustics News 98-6iNo.126j
Issued : June 25, 1998

Tokyo National University of Fine Arts & Music Inaugurates its New Sogakudo

by Toshiko Fukuchi

Exterior of New Sogakudo
On April 28, 1998, Tokyo National University of Fine Arts & Music celebrated the the opening of Sogakudo, its new concert hall. The inaugural concert featured new works commissioned for the occasion. Tokyo National University of Fine Arts & Music (affectionately called "Geidai" in Japanese) is Tokyo's pre-eminent university for the performing arts. The university's own Philharmonia performed the inaugural concert. On the program were two works commissioned for the event: "Electronic Symphony No. 5, Space Composition by Electronic Sounds and Visual Images" by Hiroaki Minami, and "KAIGEN-E for two soli, Mixed Chorus and Orchestra by Teruyuki Noda.

The new Sogakudo stands in full view of its predecessor, also known by the name of "Sogakudo, which literally means "concert hall." There is great nostalgic appeal for the original Sogakudo, as it represents one of the first Japanese buildings designed for "Western" music. Recognizing this historical value, the university has repaired and preserved it as a landmark in Tokyo's Ueno Park. The new concert hall was built on the plot of land occupied by the original Sogakudo, and the original structure is now located beyond the gates of the university's music department. When viewed from the new Sogakudo, the red brick exterior of the original concert hall can be seen in the distance, surrounded and partially cloaked in the trees of Ueno Park.

The new concert hall seats 1,140 persons. It is a shoebox configuration with one main floor and balcony seating above the sides of the main seating area. The hall's innovative design allows natural light to stream into the hall from skylights positioned at the top of the side walls of the audience area. When the ceiling is positioned at its highest setting, natural light highlights the white GRC of the ceiling, creating a unique play of light in the hall's interior. The upper walls of the hall's interior are wood that has been treated to make it non-flammable, and the lower portions of the walls are finished in light green Towada stone, a natural Japanese stone. Across the entirety of both the walls and ceiling, the surface has been purposefully designed with recesses and protrusions in order to foster dispersion. The architectural design of Sogakudo is the work of the office of Shinichi Okada. Nagata & Associates were responsible for the hall's acoustic consulting and design.

<< A Unique Solution for Adjustable Reverberation Time >>

The most truly unique feature of the new Sogakudo is its adjustable ceiling, which can be raised and lowered to achieve a range of reverberation times appropriate to different kinds of music. This ceiling represents a unique solution to the mission statement contained in the report of the university's Subcommittee on Construction of the New Sogakudo. The report stipulates that the new structure must: (1) be appropriate for orchestral and other instrumental music, string ensembles, wind and percussion ensembles, opera and choral music, traditional Japanese music, chamber music, solo vocal and instrumental music, and experimental music as well; and, in addition, must (2) adapt to the various musical characteristics of the kind of music being performed.

With the Condition of Partly Lower Ceiling at the Central Audience Area
With the Condition of Lowest Ceiling
Undoubtedly, what the Construction Subcommittee had in mind when it set the above requirements was something along the lines of the apparatus or set-ups used in many halls in order to vary reverberation time. One well-known example of this is the cylindrically shaped apparatus that can be turned one way to reflect sound and the opposite way to absorb sound. When this kind of apparatus is added to a wall or ceiling and turned so that it absorbs sound, the reflections from that wall or ceiling are diminished. However, included in the reflections from such walls or ceilings are the early reflections that are received into the hall in approximately the first 0.1 seconds after direct sound. These early reflections play a critical role in the quality and characteristics of the sound as it is heard by the audience, and the amount of these early reflections is therefore a crucial factor in achieving the desired characteristics of great concert hall sound.

Measured Reverberation Time (RT60)
The dilemma that we debated, under the guidance of our Dr. Minoru Nagata, and together with architect Dr. Shinichi Okada and his office, is that most of the performances in the new Sogakudo would be unamplified. Accordingly, the early reflections would be exceedingly important to the quality of sound heard by the audience. Therefore, Dr. Nagata and Dr. Okada decided not to use any of the available methods of varying the hall's reverberation by changing the hall's reflection surfaces. Rather, they challenged themselves to vary the reverberation time by enabling adjustments to the volume of the hall's airspace.

<< The New Sogakudo's Adjustable Ceiling >>

Positioned at its lowest setting, the new Sogakudo's ceiling is 10 meters above the stage; when raised to its highest setting, the ceiling is 15 meters above the stage. This means that the hall's volume varies from approximately 10,000 cubic meters to 15,000 cubic meters. Above the audience seating, the ceiling is divided into three sections, the height of each of which can be varied between 10 and 15 meters. In addition, a reflection panel can be lowered to hang above the stage; and its angle can be varied so that it is either parallel to the stage or slanted. When the reflection panel is in place, the hall's reverberation time can be adjusted between 1.8 and 2.6 seconds. When the stage is set with a curtain instead of the reflection panel, the reverberation time is 1.6 seconds.

<< Hard Leather Seating >>

Audience Seat with Leather Finishing
Another unusual feature of the new Sogakudo is the audience seating, which uses leather covering on hard surfaces, instead of the fabric over plush upholstering that is more the fashion in today's concert halls. Sogakudo's seats do have small cushions at the back and on the seat of each chair, but the overall impression is of the leather covering on stiff surfaces. Older concert halls in Europe and the United States used to have mostly wood or leather seating. Now, however, upholstered fabric seating is the most popular choice, in part because it reduces the echo otherwise produced in an empty hall. During the hall's design phase, we conducted repeated tests on the absorption of the leather seating. By adding absorptive finishing to the legs and underside of the seating, we achieved an acceptable level of sound absorption, approximating that of fabric-upholstered seats.

<< Sound Isolation >>

Under the road at the northwest side of the new Sogakudo runs the Keisei railroad line. To isolate the hall from the constant noise produced by trains passing along the line, we proposed and successfully had the architects adopt a "floating framework" for the structure, using vibration isolating rubber mounts. We have measured the completed Sogakudo for noise and vibration and happily confirmed that none of the trains' noise nor vibration can be detected in the new hall.

<< The Pipe Organ >>

The rear of Sogakudo's stage area is designed to house a pipe organ. Construction preparations for an organ being built by Garnier organ builders is scheduled to begin at the end of June 1998, and the organ should be fully installed by next spring.

The inaugural concert and some nine other performances were held in the short period of time between the hall's completion and the start of construction to install the pipe organ. These "Opening Concerts" included orchestral and chamber music, traditional Japanese music, opera, and other musical genres. Each was a superb performance well worth attending. Each of the university's professors who participated made full use of the stage's features and capabilities, demonstrating their passion for the new hall and its possibilities and especially delighting those of us who had participated in the hall's design and construction.

The last performance of the Opening Concerts deserves special mention. This concert was a performance of opera, and we worried that the stage did not have the right apparatus for a full-fledged operatic event. Sogakudo's stage does not have wings for the performers, nor other features often available in fully equipped opera houses. Nevertheless, the ingenuity of this concert's participants shone through as Sogakudo seemed transformed into a wonderful venue for the operatic performance of the evening. Hats off to the artistic creativity of the professors, students, and colleagues of Tokyo National University of Fine Arts & Music.

With so many possibilities available to performers at Sogakudo, those who were involved in the opening concerts were somewhat overwhelmed and uncertain about which ceiling height and other options to choose. This will be easily remedied as time passes, and I hope that the observations and measurements that we made while building the hall will provide guidance and help ensure the success of the future performers at the new Sogakudo.

Comparing Concert Hall Configurations:
Some Comments on Shoebox and Vineyard-shape Halls

by Yasuhisa Toyota

When comparisons are made of the configurations -- or shapes -- of the many concert halls that have been built around the world, the first great division that we make is between halls such as the Vienna Musikverein, Amsterdam Concertgebouw, and Boston Symphony Hall, all of which epitomize the shoebox configuration, and all other halls that are not the shoebox shape. Among non-shoebox-configured halls, the vineyard configuration -- which was pioneered by the Berlin Philharmonie Hall -- is the strongest candidate to become the alternative of choice in the construction of recent concert halls.

The appeal of the shoebox configuration derives, of course, from the excellent acoustics achieved with this shape. Current understanding credits its excellent acoustics results to the following factors: (1) the narrowness of such halls ensures a large quantity of early (short deleyed) reflections from the side walls; (2) these reflections reach every seat in the entire audience; and, (3) high ceilings produce rich reverberation. Other factors may also influence the excellent acoustics in particular shoebox-configured halls. From the design perspective, the shoebox configuration requires the acoustician to adhere strictly to proven rules about dimensions, proportions, and other aspects of hall design that make a hall precisely a shoebox configuration. On the other hand, provided the acoustician follows the shoebox guidelines, he or she can be reasonably assured of successfully designing a hall with good quality acoustics.

<< Accommodating the Trend to Larger Audiences >>

However, the trend in concert halls is to build them larger and larger. Not only is the number of seats increasing, but the seats are also roomier and the aisles between seating sections wider. If a shoebox hall built 50 years ago to accommodate an audience of 2,000 persons were built to today's standards, its seating capacity would likely be reduced by 20 to 30% to an audience of about 1,500 seats. Because the key to the shoebox configuration's wonderful acoustics rests in the early reflections from the side walls, widening a shoebox configuration to accommodate a larger audience would almost surely result in less desirable acoustical characteristics. Therefore, in order to increase the number of seats in shoebox-shaped halls, acousticians are limited to the following solutions:

(1) Extend the length of the hall.

(2) Build a balcony and create tiers of seating.

(3) Add seating around the stage (at the sides and/or the rear of the stage).

The first solution, adding length to the shoebox configuration, will of course increase the distance from the audience to the stage and, therefore, is a solution with limited applications. Of the three shoebox halls that I mentioned above, Boston's Symphony Hall is the largest, being 40 meters long from the lower back wall to the front of the stage. For both visual and acoustical reasons, It is inadvisable and unrealistic to even consider extending any hall longer than the length of the Boston Symphony Hall.

The second solution -- to add seating to a shoebox configuration by creating balconies or tiers -- can be seen in many shoebox halls, including all three of the shoebox-configured halls mentioned at the beginning of this article. The Vienna Musikverein and Amsterdam Concertgebouw each have one balcony; Boston Symphony Hall has two. However, this solution also has limitations. Large balconies that jut far into the audience area cannot be added without adversely affecting the sound in the audience seating below. The acoustics of seating under a balcony's overhang is notoriously poor compared with seating that is not underneath the balcony. In addition, balconies located at the sides of a hall result in poor sightlines for the balcony audience. In some instances, the stage can almost not be seen at all from the second and third rows of side balcony seating.

The third solution -- adding seating at the sides and/or rear of the stage -- is a solution that has also been adopted by the Musikverein and Concertgebouw. Depending on the program to be performed, these seating areas can be used by the performing chorus instead of as audience seating, and thus offer a certain versatility. Nevertheless, as a solution to the need for more audience seating, the number of seats that can be added through this means is quite limited.

<< The Dynamism of the Vineyard Configuration >>

The most salient characteristic of the Berlin Philharmonie Hall is the central location of the stage. In particular, the conductor stands virtually at the center of the hall and the audience seating surrounds and encompasses the hall's performers. In discussing the vineyard configuration, I mention the Berlin Philharmonie Hall first because it was the pioneering success of this hall that established this configuration as a viable alternative to the shoebox shape. Another name for vineyard configuration is arena configuration, because of the way the audience seating is arranged vis-a-vis the stage area.

The most valued advantage of the vineyard configuration is that every seat is as close to the stage as could possibly be, resulting in a sense of intimacy and connectedness between the audience and the music created on stage. Whereas the ambiance in shoebox halls is a passive audience-stage relationship, the ambiance in vineyard halls is dynamic. The vineyard configuration fosters a lively sense of interaction between the audience and the performers on stage.

<< Vineyard Configuration Acoustics >>

One of the most important acoustical characteristics of the vineyard configuration is how the walls that demarcate blocks of audience seating enhance the effectiveness of early reflections. The seating areas of a vineyard-configured hall are comprised of blocks of seats staggered or terraced so that their walls can be used acoustically to produce the early reflections that are so critical to excellent hall acoustics. By increasing the number of blocks, and thereby the number of wall surfaces in proximity to audience seating, it is possible to produce excellent acoustics in a concert hall of quite large size.

However, the flexibility of the layout of a vineyard-configured hall becomes more and more complex. This makes it difficult for the acoustician to calculate and predict the hall's acoustical characteristics. In certain cases, intensive testing of scale models is essential to the successful design of a vineyard-configured hall, and the additional input of time and consideration to evaluate the acoustics of a vineyard configuration lead to increased costs as well. Nevertheless, compared with the shoebox configuration, the vineyard configuration offers greater flexibility in hall design. For large halls of 2,000 or more seats, the vineyard configuration also affords greater freedom of possibilities to the hall's overall architectural design.

<< In Summary >>

The benefits of shoebox and vineyard hall configurations are shown in the table below. Looking at halls that are already familiar to us, we notice that excellent shoebox halls have comparatively smaller air room volume. They are best suited to performances by small and medium-sized orchestras and ensembles. The acoustical impression is tight and with concentrated quality, giving one the strong impression that the hall itself is an instrument producing the wonderful sound. Vineyard configuration halls are mostly large in size, and they are well suited to performances by large orchestras and ensembles. Acoustically, vineyard-configured halls offer audiences a feeling of expansiveness; the music can soar and grow, and seems to stretch or expand to touch each audience seat directly. The clarity of sound experienced by vineyard hall audiences is also especially high. The listening experience in both shapes of halls can be enchanting and memorable, but they may be something different experiences indeed.

Comparison of Shoebox and Vineyard Hall Configurations

Appropriate sizesmall-to-medium
(under 2,000 seats)
(1,500 seats or larger)
Excellent Acousticscomparatively easy to achieveintensive studies, much more testing required
Characteristics / Ambiancehistoric, classical, formalmodern, dynamic
Visual impressionpassive, statelymodern, dynamic
Ability to design developmentsmallrelatively large
Names of prominent hallsVienna Musikverein
Amsterdam Concertgebouw
Boston Symphony Hall
Symphony Hall Birmingham
Kioi Hall
Kyoto Symphony Hall
Sumida Triphony Hall
Berlin Philharmonic Hall
Leipzig Gewandaus Hall
Cardiff Hall
Suntory Hall
Sapporo Concert Hall

Nagata Acoustics News 98-6iNo.126j
Issued : June 25, 1998

Nagata Acoustics Inc.

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