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

Nagata Acoustics News 01-3 (No.159)
Issued : March 25, 2001

Konosu City Cultural Center Opens

by Akira Ono

<< Overview of Konosu City and its New Cultural Center >>

Claire Konosu (exterior)
Konosu City, in Saitama Prefecture, is famous in Japan for its workshops and craftspeople who make the elegant and detailed porcelain and cloth dolls called hina ningyo. Traditionally, these dolls are displayed only for a few days leading up to the third day of the third month of the year, called Momo no Sekku. The dolls are dressed in attire from ancient Japan's Imperial Court and a set may depict not only the Emperor and Empress, but also an entire entourage of court personages, including retainers and musicians. The finely crafted hina ningyo can become family heirlooms handed down from mothers to daughters and treasured for future generations. Towards the end of February and through the first three days of March, displays of hina ningyo decorate the Konosu City train station as well as City Hall and other prominent public locations.

In this city with strong ties to Japanese traditions, a new cultural center named Claire Konosu was completed in September 2000. The architectural design of the center was selected using a design competition held in 1996 by the Saitama Prefecture Design Nomination Selection Committee. C&A (Cerecans and Associates) won that competition and became the architects for this project.

The cultural center building houses a large hall with a seat count of up to 1,300, a 300-seat small hall, a rehearsal room, a gallery and meeting rooms, as well as commercial space for restaurants and an advance sales ticket counter operated by an independent vendor who sells tickets for a wide range of performing arts, cinema, and sporting and other events to be held throughout Japan. The center's site includes a park on the south side of the cultural center building. The park and the cultural center were designed together and the result is a casual and welcoming environment where the city's residents instinctively feel at ease.

<< The Center's Energy-saving Exterior and Its Acoustical Impact >>

The roof and entire exterior walls of the Konosu City Cultural Center are finished with layers of slats spaced evenly 300 mm (1 ft) apart. In addition to creating this design for aesthetic reasons, the architect anticipates that the adoption of this design will reduce the center's summer energy costs by deflecting some of the sun's hot summertime rays and minimizing increases in the building's indoor temperature even as the outdoor air temperature increases to uncomfortable levels.

However, the exterior design caused us grave acoustical concern. If a strong wind hit the slats, we knew that an unpleasant whistling noise would result. This phenomenon, in which slats or railings aligned equidistantly from each other cause a loud and unpleasant high-pitched sound on windy days, is well documented in presentations and reports at professional acoustical seminars and association gatherings we attend. The documentation by other acousticians warns that the wind noise generated by such structural elements can be heard both inside the building and in nearby neighborhoods, leading to claims and remedial work.

The design plan for the Konosu Cultural Center called for installing the slats over the entire exterior of the building, excluding only the windows from this treatment. Given the extensive use of slats in this project, and our knowledge of problems encountered by our colleagues on other comparable projects, Nagata Acoustics felt that a wait-and-see approach would be inadequate. Konosu is known to be a windy city, and if the new cultural center caused unpleasant noise whenever the wind blew strongly, there would be both public uproar and almost no way to remedy the problem without huge expenditures of both time and money.

<< Our Preventive Approach to Eliminating Wind Noise >>

Our first step in devising an anti-wind-noise strategy was to review the available options. Among the remedies known to acousticians, one is to cover the slats or rails with netting. Another option known to be effective is to coat the slats with zinc plating, thereby adding roundness to the edges of each slat. We decided to use the zinc plating option.

Prior to implementing our wind-noise prevention strategy, we tested our plan with the help of Koike-gumi Company, the project's general contractor. Using indoor space at Koike-gumi's technical design unit, we generated strong winds and blew them against rounded, zinc-coated slats. We tested a variety of wind speeds and directions. After our tests showed that the slats were noise-free under all conditions, we gave the contractor the go-ahead to install the zinc-coated slats. Konosu City continues to have strong winds, but the new cultural center withstands them quietly and six months of operation without complaint continue to validate the strategy we adopted.

<< The Konosu Cultural Center Large Hall >>

The large hall
Konosu City, the project client, required that the new cultural center's large hall be capable of varying its seat count between about 800 seats and 1,300. Our response was to design a space capable of four configurations using mechanisms to either vary the space occupied by the on-stage reflection panels or deploy partition walls to change the size of the audience seating area of the hall or a combination of these options. The downside of creating these options is that deploying the stage reflection panels entails complex set-up procedures involving both time and labor whenever their configuration is changed. In the future, I would like to see alternative solutions develop that will provide less labor-intensive, low-budget ways to achieve this kind of configuration flexibility.

The large hall's interior has a uniquely asymmetric design. The side balcony at stage left doubles as an access from the main floor seating to the second level seating at the rear of the stage, while the stage right side balcony doubles as an access to a third level of balcony seating that is also at the rear of the stage. Almost all of the surfaces in the large hall's interior are painted black, adding to the striking visual uniqueness of the hall. For acoustical reasons, we installed parallel, 80 cm-wide (31.5 in) eaves at approximately 2 m (6.6 ft) intervals along the side walls of the hall. The purpose of these protrusions is to increase the likelihood of sound reflections from the rear wall of the hall reaching the central portion of the audience area.

<< A New String Ensemble for the New Cultural Center >>

In connection with the planning and development of the new physical facility, the project's client planned the establishment of a new string orchestra named Ensemble Konosu Virtuoso. Maestro Masaki Sakurai, who was already a resident of the Konosu community, will lead the new orchestra. Ms. Yasuko Ohara, concert master of the Tokyo Symphony Orchestra, will serve as concert master. Ensemble Konosu Virtuoso is a string ensemble of 24 positions, 15 of which were filled by auditions open to the general public.

Saitama Prefecture is a prefecture close enough to the Tokyo area that its population is filled with many communities of bedroom towns, as well as having communities like Konosu that have roots in traditional craft production. The prefecture is now dotted with many fine halls, but Konosu is the first hall in the prefecture to invest in a professional orchestra with a particular hall as its home.

Ensemble Konosu Virtuoso inaugurated the cultural center's opening with its first subscription concert in October 2000. The new orchestra was exuberantly welcomed to its new performance home and played to the hall's maximum full house of 1,300 seats. Annually, Ensemble Konosu Virtuoso currently plans to perform two subscription concerts in the new cultural center, one concert in the spring and one in the fall.

Sound Systems for the Two New Halls of the Konosu Cultural Center

by Makoto Ino

<< The Large Hall's Sound System Parameters >>

In designing the sound system for the Konosu Cultural Center large hall, Nagata Acoustics focused on the following functionalities:

* Amplification of speech-voice, musical instruments and sound effects throughout the large hall and to ancillary rooms connected to the hall;
* Recording and playback devices;
* Communication systems among technical and backstage staff during both pre-performance set-up activities and performances.

To maximize the convenience and usability of the sound system, we chose digital mixers for both the large(RAMSA WR-D500) and small(RAMSA WR-DA7) halls' sound systems. Additionally, for the large hall, we used an AES/EBU digital connection between the mixing-console and the digital graphic-equalizer(GEQ) to minimize the deterioration of original sound.

<< The Large Hall's Speaker System >>

The large hall has main speakers at the center of the upper proscenium and at both front sides of the stage. Because the large hall can be adapted to four different configurations, we considered developing a plan to include moving each of these speakers as part of the set-up for each configuration. This would have enabled us to obtain optimal speaker placement for the main speakers with each configuration. However, since each of the speakers weighs about one ton, we decided that it would be impractical to try and move them every time the stage is reconfigured. Instead, we opted to fix the placement of the main speakers so that they achieve optimal performance in the configuration that will probably be used the most frequently. This is the configuration in which the stage occupies a central position, with audience seating behind as well as in front of the stage.

<< Deployable Speakers for Both Halls' Stage Configuration Variations >>

When the large hall stage configuration is varied, smaller extra speakers are deployed to enhance the sound from the main speakers. In addition, because the stage proscenium is designed to have a visibly smooth and flat surface, for aesthetic reasons, we designed the installation of the main side speakers so that they can be manually pulled flush with the walls when they are not in use. We also installed numerous ceiling and wall speakers for use with sound effects.

Because the Konosu Cultural Center Small Hall is a multipurpose space, we limited its fixed speakers to ceiling speakers and provided for movable stage side speakers to be deployed when the hall's stage is set up for use.

<< On-stage Microphone Jacks >>

We specified 170 microphone circuits for the large hall's stage, but restricted ourselves to a simpler plan of 40 circuits for the small hall. In order to use the direct digital input/output capability of the large hall's digital mixer, we also installed AES/EBU circuits on the large hall's stage.

<< Digital Peripherals and Analog Microphones >>

We selected digital equipment for the large hall's recording device, effecter and other peripheral devices. But because microphones are still analog, this means extra work to ensure that the inputs and outputs of the large hall's digital mixer are appropriately and separately set to either the hall's digital devices or analog microphones. While virtually all line-in/out audio devices will be digital devices within the near future, until microphone output becomes digital, sound mixers will continue to need the capability to receive analog input. In the past, sound mixers were equipped for switching between microphone and line input, but in the future, the switching capability will need to be between analog and digital input. Otherwise, mixers will need an unwieldy number of ports and channels to accommodate all of the digital devices and analog microphones as well.

<< Amplified Sound Quality >>

The quality of a hall's amplified sound depends on the care and precision of the final adjustments after installation of the sound system equipment. At Konosu Cultural Center, the large and small halls together required just under two weeks of sound system fine tuning. Most of the adjustments involve the speakers, but the connections between the mixer and the GEQ, the power amplifier and the speakers can also not be ignored.

At Konosu Cultural Center, the reputation of both halls' amplified sound awaits the use of the new digital sound mixers. When I performed the fine tuning work, my impression was that the digital mixers produce a clearer sound with less added tone color than analog mixers. An advantage of the digital mixers is that the young sound technicians of the cultural center were able to completely master the mixers' operation in just a few days, a feat not possible with analog mixers. In addition, not only were the young technicians able to achieve consistently natural sound on a quick learning curve, but all of the desired settings could be programmed into the mixer's memory. The digital mixers make day-to-day operation of this equipment easy for halls that may or may not have experienced staff.

For more information about Konosu Cultural Center, "Claire Konosu," contact the center directly at +81-48-540-0540.

On Accepting the 11th Nippon Steel Music Awards' Special Award

by Dr. Minoru Nagata

Dr.Nagata giving speech at the ceremony
As was mentioned in last month's "News and Opinions," I recently had the honor of receiving the 11th Nippon Steel Music Award's Special Award. An awards ceremony was held at the Hotel Okura, in Tokyo, on February 27, 2001. Until I was notified that I was named to receive this award, it never occurred to me that my work as an acoustical engineering consultant might be recognized in terms of its contribution to the world of music. My surprise at the announcement added an extra measure of sweetness to the joy with which I accepted this award. My first words of gratitude must go to the Nippon Steel Cultural Foundation and the foundation's esteemed Music Awards panel of judges who, in recognizing me, have fittingly shown their broader recognition and understanding of the role and value of acoustical design work in the context of the art of musical performance.

<< My Start in the Profession 50 Years Ago >>

This year marks the 50th anniversary of my entry into the profession of acoustical design. In 1951, I was in my third year of employment at the NHK Technical Research Laboratories and I was assigned to my first hall project. NHK (Japan's equivalent of the BBC) was then located on a small plot of land in the Tamura-cho section of Shimbashi, a colorful section of Tokyo perhaps most well known in the 1950s for the JOAK Building of Japan Broadcasting Cooperation and for its many bars and other night spots. It was still the early post-World War II era, and NHK planned an expansion of its facilities as part of the reconstruction that was happening throughout the city. The NHK Hall included in this project had a seat count of slightly less than 700.

While NHK had a pre-war track record of accomplishments in broadcasting studio construction and technology, when we began work on this first NHK Hall we had virtually no reference materials or technical papers on hall acoustics. Today, Japanese music fans may be as familiar with the Vienna Musikverein as if it was located in their own country, but in the early 1950s it must not yet have reopened, because we had no information on this exemplary hall. The only hall that we knew about was London's Royal Festival Hall, which had opened in 1950. We had one pamphlet about this hall to help provide us with inspiration.

<< The Arrival of Television Changes Hall Use >>

The original NHK Hall was planned and designed to be a concert hall, and the layout included space for future installation of a pipe organ. When the hall opened in 1955, and in its first years, the hall did operate as a concert hall. However, as television grew in popularity, this hall became known among the Japanese public as the hall they saw whenever an NHK television program included audience participation. The NHK Hall in Tamura-cho maintained its high profile, TV-related reputation until it was replaced by a new hall, the considerably larger NHK Hall in the Shibuya section of Tokyo opened in 1974. The hall in Shibuya continues in use today.

<< Japan's Classical Music Scene in the 1950s >>

By 1955, when the first NHK Hall opened, most of the chaos of postwar daily life was gone. Classical music concerts began to be scheduled and attended. Before NHK Hall became a reality, there had been only one venue for classical music performances, Hibiya Kokaido, built in 1922.

The decade of the 1950s predates the rise of the consumer audio industry in Japan. Then, Japanese classical music fans' only way to satisfy their cravings for classical music was to listen to NHK radio broadcasts. Once NHK Hall opened, noteworthy international performers and ensembles began to come to Japan to perform in the new concert hall. NHK broadcast these concerts and radio became the medium by which classical music reached homes in every corner of the Japanese islands. The first NHK Hall served an important role in spreading the love of classical music throughout Japan during this formative period of Japan's postwar development.

<< The First NHK Hall's Acoustical Leap Forward >>

The rich and vibrant acoustics of the Tamura-cho NHK Hall made a startling impact on all of us in Japan who loved classical music but had previously known only the sound of Hibiya Kokaido. Even now, I can recall the thrill that audiences, including myself, felt the first time we listened to a live classical music performance in the Tamura-cho NHK Hall. I am certain that the delight and wonder experienced at Tamura-cho NHK Hall became a guiding light and inspiration for the acoustical engineering and design discipline that grew thereafter in Japan.

<< Four Progress-filled Decades from the 1960s to Today >>

In the 1960s, Japan entered one of two major hall-building periods. In addition to the design and completion of Tokyo Bunka Kaikan, municipalities and prefectures around the country funded the construction of community center halls and similar facilities. It was Japan's golden age of the multipurpose hall. The second hall building boom came in the 1980s, but this time the halls built were concert halls or other specialty halls. In Tokyo, in particular, one can now find concerts being performed at more than 10 large and small halls on nearly every day of the year.

Because of the current Tokyo environment, I have the good fortune to be able to listen to a variety of performance types in a variety of rooms. My listening experiences influence the objectives and direction I set in engineering new acoustical designs and aid me when I work on the finishing details of a room's acoustics. I consider myself extremely lucky to be living in a place and time that is so driven to building and using such an unprecedented number and variety of halls. I frequently learn something of benefit to my own work by listening to performances in the many spaces so close to my own doorstep. What a contrast with the desert of example and inspiration that Tokyo was when I began my career 50 years ago!

<< The Concert Hall's Role in a Musical Performance >>

Some commentators liken concert halls to a musical instrument. But there is more distance between a hall and a performer or ensemble than between musicians and their instruments. Hall plans are subject to any number of restrictions and limitations and there is often a tug-of-war of individuals' opinions, emphases and points of view. A hall is shaped by its site and budget, by its owner's intentions and its architect's likes and dislikes and by other influences as well. On occasion, one or more of these influences pushes the design of a hall dangerously toward losing the essence of its basic function, which is to be a performance space.

The acoustics of recently built Japanese halls are recognized internationally for the high standards of excellence achieved. One important reason why these halls' acoustics are so successful is that all of these projects' participants prioritized the halls' acoustics. Everyone who had a hand in any stage of these projects understood the importance of achieving fine acoustics and cooperated in achieving this goal.

Advances in the discipline of acoustical engineering have also contributed to the excellent acoustics of new halls, especially the trend in concert hall acoustics to focus on lateral close reflections, as well as improvements in measurement, analysis and simulation technologies. In addition, advances in noise abatement and construction technologies have matched the progress in room acoustical design engineering and also contribute significantly to today's halls acoustical successes.

<< On a Personal Note >>

The surprise honor of receiving the Nippon Steel Music Awards Special Award gives me a unique milestone. From this point forward, I will both reflect on the fundamental essence of music as a cultural phenomenon nurtured in the long course of history and, in the time that remains to me, continue to devote myself to endeavors that advance the content and stature of the field of acoustical engineering.

In accepting the Nippon Steel Award, I especially want to express my indebtedness to my mentors at NHK and to my colleagues in the Architectural Acoustics Group in the NHK Technical Research Laboratories with whom I worked to lay the foundations for today's engineering of acoustical design in Japan. I also wish to acknowledge my profound gratitude to all of the employees of Nagata Acoustics and to my family, who have shared with me all of the challenges and difficult times, as well as the joys, that we have faced since I founded Nagata Acoustics 30 years ago.

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Nagata Acoustics News 01-3(No.159)
Issued : March 25, 2001

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