Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 09-06 (No.258)

Issued : June 25, 2009

[ Japanese Version ]

ZA-KOENJI Public Theatre-Tokyo's Lively New Venue Opens in Koenji

by Ayako Hakozaki

ZA-KOENJI Public Theater Exterior
ZA-KOENJI Public Theater Exterior

There's an unusual new structure visible from the windows of Tokyo's JR Chuo Line trains. At first glance, I was tempted to ask, "Could this be a huge chunk of chocolate from which one big bite is missing?" Or, a bit more realistically: "Could the new structure be just a big brown tent?" In fact, last month, just a five-minute walk from the JR Chuo Line's Koenji Station, on a piece of land very near the intersection where the JR railroad tracks cross over Tokyo's major "Kan-7" loop road, Suginami Ward's new ZA-KOENJI Public Theatre opened its doors for performances for all ages and for audiences seeking both serious drama and fun. (The "ZA" of the theater's name is a pun on Japanese pronunciation of the English word "the" and the word for theater seat, "za.")

ZA-KOENJI replaces the now demolished, old Koenji Civic Auditorium, which stood on the same site. Architect Toyo Ito designed the building and Taisei Corporation built it.

<< Overview of ZA-KOENJI Public Theatre's Facilities >>

One half of the new theater building's spatial volume is above ground and the other half is underground. When visitors enter the building, they are amazed to discover that the facility is much more spacious than they assumed it would be based on the building's exterior.

Cross section view of building layout
Cross section view of building layout

Overall, the building has six floors. A theater named "ZA-KOENJI 1" occupies the top floor. A civic auditorium named "ZA-KOENJI 2" and a space named AWAODORI HALL occupy the first two underground levels, and the third underground level has multiple practice rooms, stage scenery ateliers and rooms for creating costumes, sound effects and projected media for theater productions. In addition, the second and the third level houses an archive of play manuscripts and other materials related to modern Japanese theater, and Café Henri Fabre, both of which are open to the general public without purchasing theater tickets.

This publicly funded facility combines under one roof two theaters that accommodate audiences of 250 persons each, with one theater intended for professional performances and the other expected to be used primarily by community groups and clubs for amateur productions. The focus on theater performance and the combination of professional and amateur use facilities makes ZA-KOENJI Public Theatre unique among public cultural facilities. The theater focus of the entire ZA-KOENJI building distinguishes it from Suginami Kokaido, the concert hall opened three years ago in nearby Ogikubo (two train stops away from Koenji) and compartmentalizes Suginami Ward's theater and concert hall performing arts activities into separate facilities.

<< ZA-KOENJI's Designated Administrator, Artistic Director and General Manager >>

The operational planning for ZA-KOENJI began three years prior to the theater's opening when the building's detailed design drawings were complete and the non-profit organization Creative Theatre Network (CTN) won the competition to become the theater's designated administrator. After the competition selected CTN's proposal, the non-profit organization also successfully completed participation in a series of hearings held as part of the designated administrator selection process.

During the project's next phase of building construction, the newly selected designated administrator provided opinions and input that resulted in some design changes being incorporated during the construction phase of the project. In the construction industry, the "face" of a building project's end user often remains hidden from the builders during the construction phase of a project. In the case of ZA-KOENJI, the construction project benefited from the early selection and participation of the designated administrator.

ZA-KOENJI's artistic director is Mr. Makoto Sato, who also served as Suginami Ward's advisor on the project from the beginning of the conceptual programming phase. Many theater aficionados in Japan know Mr. Sato's work from his previous tenure as the artistic director of Setagaya Ward's Public Theatre. ZA-KOENJI's General Manager is Mr. Ren Saito, president of CTN and an accomplished playwright.

<< Sound Isolation Designs for ZA-KOENJI's Facilities >>

ZA-KOENJI 1 configured with stepped seating
ZA-KOENJI 1 configured with stepped seating

The architectural design of ZA-KOENJI Theater stacks two theaters, AWAODORI HALL, practice rooms and other support rooms above and below each other to fit them onto the building's narrow site. In order for the community to obtain maximum use of the building, all of the building's facilities need to be able to be used simultaneously. To this end, we aimed to create a high level of sound isolation performance for each room.

On this project, sound isolation planning ranked very high among our acoustical design priorities. Fundamentally, for each of the two theaters and AWAODORI HALL we specified anti-vibration and sound isolating structural designs to address both the sound isolation requirements and to prevent noise and vibration from the nearby railroad line.



Volunteers practice a drumming routine in AWAODORI HALL to confirm its sound isolation properties.
Volunteers practice a drumming routine
to confirm its sound isolation properties.

The layout of the rooms played a pivotal role in our design strategies. Civic auditorium ZA-KOENJI 2 is located on the second level underground and surrounded by other facilities. ZA-KOENJI 1 is directly above it, a main practice room is directly below it, and AWAODORI HALL is on the same second underground level. For ZA-KOENJI 2's anti-vibration and sound isolation design we specified a concrete floating floor on an elastic, anti-vibration material and a free-standing steel frame. Also, we added multiple layers of fiber-reinforced gypsum panels on the frame to enhance the anti-vibration and sound isolation performance levels. We adopted the same structural design for AWAODORI HALL. The accompanying photo of AWAODORI HALL was taken during a sound isolation performance confirmation test we conducted in the hall with local community volunteers after the completion of construction.

To achieve an effective anti-vibration and sound isolation design for ZA-KOENJI 1, we considered the significance of all of the other facilities being located below it, and designed a container-like anti-vibration and sound isolation structure that encases the theater's walls and floor (but not the theater's ceiling). In addition, on the walls' sound isolation layer, as well as on the interior walls, we applied cast glass fiber reinforced concrete (GFRC) panels to the steel plates.

<< Addressing the Square Shape of ZA-KOENJI 1 >>

Unlike most theaters, ZA-KOENJI 1 Theatre has a square footprint and the floor can be configured as either a flat or stepped floor. To prevent the possible occurrence of flutter echoes, we specified the installation of reversible panels below the technical gallery. Each panel is sound reflecting on one side and sound absorbing on the other side. The panels can be reversed based on the acoustical needs of each performance.

<< Opening Performances and Upcoming Major Awa Odori Event >>

ZA-KOENJI opened on May 1, 2009, in the middle of the annual "Golden Week" of Japanese national holidays. For families with children, and adults looking for light-hearted entertainment, the opening events included a Picture Book Carnival and numbers of street performance artists scheduled one after the other in front of the building, throughout the lobby and in ZA-KOENJI 1 Theatre, with access to all three areas opened to create one large and continuous space. For the theater-goers, the opening-day program offered a performance of Hisashi Inoue's "Makeup" in ZA-KOENJI 2. "Makeup" is a one-woman solo performance starring Misako Watanabe. The building was packed with visitors and audiences of all ages visibly enjoying the new facility.

ZA-KOENJI's regular play performance schedule will feature three kinds of programming. One third will be devoted to works chosen by the Japan Playwrights Association, one third will be works chosen from acclaimed plays previously performed in Tokyo (and staged in partnership with the performing organization) and the remaining one third of the programming will focus on works that appeal especially to children. Also, with the support of private companies primarily located in Suginami Ward, ZA-KOENJI will encourage theater attendance by selling reduced-price ticket books good for attendance at multiple performances.

Another initiative planned for ZA-KOENJI is the establishment and operation of an academy that will offer a two-year training program in theater arts. This program will be developed in collaboration with specific universities and other public culture centers and public theaters. The goal of this initiative is to nurture the future generation of theater professionals.

One special event that will take place in August specifically links the new building with the local traditional culture. The new building will be a supporting venue for some of the activities of the 190 Awa Odori dance troupes that come to Koenji annually to participate in the Awa Odori Festival. This festival typically draws upwards of 1,200,000 spectators. ZA-KOENJI opened with a festival-like atmosphere and it seems certain that the festival enthusiasm at ZA-KOENJI will become an enduring part of the personality of this new public theater.

ZA-KOENJI's home page is http://www.za-koenji.jp/english/about/index.html

The Effects of Diffusion on Room Acoustics -1

by Dr. Minoru Nagata, Founder of Nagata Acoustics

What comes to mind when we think about the phenomenon described by the word "diffusion"? If we add droplets of ink to a glass of water, the water and ink mix to become a pale-blue liquid. Likewise, sounds can be in a diffuse state. When a sound has uniform strength everywhere in a room and, in addition, the sound flows at all points in the room and from all directions, the sound is said to be in a diffuse state. A space with this condition is called a diffuse sound field.

Now that I've stated a definition of what sound diffusion is, let me further ask: Do we know what kind of acoustical effects diffusion produces? Everyone has a sense that diffusion makes the quality of a room's acoustics more precise or subtle, but does diffusion cause any intrinsic changes in the timbre of instruments? If diffusion does cause this kind of change, does that make a diffuse sound field the ultimate ideal concert hall space?

The topic of sound diffusion raises many questions. In this article, I will focus my discussion on sound diffusion and its acoustical effects in concert halls. However, I also want to make note that sound diffusers and sound diffusion structures play an important role in concert hall design beyond their value as elements of acoustical design. For architects, who must accept a large number of constraints when creating the architectural designs of concert halls, sound diffusers and sound diffusion structures are among the few elements of a concert hall that allow the architect a relatively unbridled opportunity for artistic expression.

<< Polycylindrical Diffusers -- One of the Earliest Diffuser Shapes >>

Fig. 1: American radio studio
Fig. 1: American radio studio

Fig. 2: Kanagawa Kenritsu Ongakudo
Fig. 2: Kanagawa Kenritsu Ongakudo

Fig. 3: Former (Shinbashi) NHK Hall
Fig. 3: Former (Shinbashi) NHK Hall

When I joined NHK Technical Research Laboratory, in 1949, one of the first technical papers that came into my hands ("Polycylindrical Diffusers in Room Acoustical Design," by J.E. Volkmann, in J. Acoust. Soc. Am. 13, 234 [1942]) discussed the use of polycylindrical diffusers of the kind installed in the American radio studio shown in Fig. 1. This paper dates back to more than 60 years ago. At the time, use of this kind of diffuser enabled increased ease and flexibility of locating recording microphones, and these diffusers became widely used in broadcasting and recording studios in the United States.

In Japan, during the same period, broadcasting and recording studios were built with interior walls covered in a material that I recall was made from kapok tree fiber, in order to make the studio spaces sound absorbing. When I read about the polycylindrical diffusers, I was amazed to discover such strange-looking objects appearing on the walls of studios.

Today, when I visit a concert hall, from the stage to the length of the sidewalls, I see sound diffusers with shapes that may protrude like mini-mountain ranges or have accordion-like folds, and I see ceilings with curves that undulate like waves, all of which are design elements that truly belong in a concert hall interior. These kinds of elements clearly demonstrate a designer's intent to create an acoustically diffuse hall space. In Figs 2 and 3, the reader can see Kanagawa Kenritsu Ongakudo and the former (Shinbashi) NHK Hall, the first concert halls built in Japan after the end of World War II. Both of these halls have sound diffusing sidewalls designed using a standard acoustical engineering approach to the placement of sound diffusers in appropriate locations along the walls.

<< The Great Diversity of Sound Diffuser Shapes >>

Sound diffuser shapes and structures are the design focus of not only a concert hall's acoustical consultant, but also design elements of great interest to architects as well. The diffusers' sizes, shapes, degree of protrusion and placement matter very significantly to both the designer of the hall's room acoustics and the architect. The acoustical and architectural professionals on a hall project strongly communicate their requirements, visions and objectives to each other and, while they sometimes begin with very divergent ideas, through tough persistence they achieve a diffuser design that satisfies both the project's acoustical and architectural aims.

The wood diffusers on the front sidewalls of Tokyo Bunka Kaikan's Large Hall provide a good example of diffusers that fulfilled the requirements and visions of both the hall's architect and acoustician. Three men: the late architect Kunio Maekawa; sculptor Ryokichi Mukai, who had chief responsibility for the diffusers' design; and the late Yasuo Makita, who had overall responsibility for the hall's acoustics, collaborated to create these wall diffusers.

Fig. 4: Bunka Kaikan's Large Hall
Fig. 4: Bunka Kaikan's Large Hall

To build the sound diffusers for Bunka Kaikan's Large Hall, the project contracted the work to Tendo Mokko, a company equally famous as crafters of wood "shogi" (Japanese chess) pieces and as the creators of molded plywood furniture. Tendo Mokko's implementation used multiple wood panels vertically layered to achieve a single, integrated diffuser system (Fig. 4). The size and depth of the myriad, uniquely shaped cut-out sections of the wall followed requirements specified by the acoustical design. Next year, Tokyo Bunka Kaikan will celebrate its 50th anniversary. In the deep crevices of the Large Hall's sound diffuser walls can be found the origins of the past 50 years of Japanese acoustical room design methods and achievements.

I will also mention here a number of other architect-acoustical consultant collaborations that resulted in notable hall sound diffuser designs. In Fig. 5, the reader can see one of the tile sound diffuser sidewalls of Fukushimashi Ongakudo. Architect Shinichi Okada's design for this wall combines large wedge-shaped protrusions with narrow vertical wedge strips on the protrusions to create additional sound diffusing surfaces.

 Fig. 7: Tsuda Hall 
Fig. 7: Tsuda Hall

 Fig. 6: Nihon University's Casals Hall 
Fig. 6: Nihon University's Casals Hall

 Fig. 5: Fukushimashi Ongakudo 
Fig. 5: Fukushimashi Ongakudo

Fig. 6 shows Nihon University's Casals Hall, which has sidewalls shaped like hanging cloth curtains. To construct these walls designed by architect Arata Isozaki , actual cloth curtains were used to create molds which were then used to form precast concrete panels.

Lastly, Fig. 7 shows the gently undulating peaks of Tsuda Hall's sidewalls. For this hall, architect Fumihiko Maki selected small tile blocks to give the sidewalls effective sound diffusion properties.

In this article, I discussed some good examples of hall sound diffusers. In a next article, I will share some thoughts about the relationship between sound diffusion and sound absorption.

Nagata Acoustics Inc.

(Tokyo Office)
Hongo Segawa Bldg. 3F, 2-35-10 Hongo
Bunkyo-ku, Tokyo 113-0033, Japan
Tel: +81-3-5800-2671, Fax: +81-3-5800-2672

(LA Office)
2130 Sawtelle Blvd., Suite 307A
Los Angeles, CA 90025, U.S.A.
Tel: +1-310-231-7818, Fax: +1-310-231-7816

(Paris Office)
75, avenue Parmentier
75011 Paris, France
Tel: +33 (0)1 40 21 44 25, Fax: +33 (0)1 40 21 24 00

E-mail: info@nagata.co.jp

[ Japanese Version ]