Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS


News 12-04 (No.292)

Issued : April 25, 2012

[ Japanese Version ]

Tokyo Metropolitan High School of Arts' New Campus Completes

By Akira Ono and Ayako Hakozaki

Rendering of the completed Tomihisacho Campus
Rendering of the completed Tomihisacho Campus

Tokyo has just one public, "magnet" high school for artistically talented youth. Named Tokyo Metropolitan High School of Music & Fine Arts until 2010, in that year, the school both celebrated its 40th anniversary and renamed itself to the more genre-inclusive Tokyo Metropolitan High School of Arts. The school did not only change its name; it also added to its curriculum. Previously, the school had a music track and a visual fine arts track. Now the school also offers a third stage performing arts track that includes theatre arts and dance.

The renamed high school temporarily maintained two campuses, one in Meguro's Komaba for students specializing in music training and the Kagurazaka Campus in Shinjuku's Yaraicho for students specializing in fine arts or stage performing arts. Meanwhile, the school obtained a site in Shinjuku's Tomihisacho that was formerly Koishikawa Technical High School and construction of the new High School of Arts campus began to bring all three divisions of the school to the same location. Recently, the new campus completed and the divisions of the school reunited in the Tomihisacho location.

Tokyo Metropolitan High School of Arts has a long and venerable history of educating young musicians, painters and other artists. Its Music High School Division has educated many world class professionals, such as soprano Yumiko Samejima. On a personal note, one of us (Akira Ono) attended a middle school that used to be located adjacent to the Komaba Campus of Tokyo Metropolitan High School of Music & Fine Arts and has fond memories of looking out the window towards the high school. The younger students at the middle school, named Meguro Daiichi Middle School, could see the high school's students sitting outside on the Komaba Campus grounds sketching or playing a musical instrument. Typically, the high school students sported long hair in the style worn by Ryuichi Sakamoto and they dressed in casual street clothes, unlike most Tokyo public school students who wore uniforms. The high school students always seemed more like adults than children and the Meguro Daiichi Middle School students were quite in awe of the young musicians and artists who attended Tokyo Metropolitan High School of Music & Fine Arts.

<< Overview of the New Tomihisacho Campus Project >>

Music hall
Music hall

Large space for choral practice
Large space for choral practice

The architectural firm of Matsuda Hirata Sekkei designed the new school campus and a joint venture led by general contractor Matsui Kensetsu was responsible for the project's construction. AGK Acoustic Engineering Co., Ltd. served as the soundproofing contractor. Most of our readers probably associate Shinjuku with the skyscrapers in the environs of Shinjuku Station. But the Tomihisacho section of Shinjuku is a quiet residential neighborhood.

The plan for the new campus retained the old Koishikawa Technical High School's gymnasium building at the center of the site, added a music hall building to the west and a 4-story, reinforced concrete classroom building to the east. The interior of the gymnasium was remodeled and converted to rooms primarily for use by the stage performing arts students. The interior now has rooms with stages for the performance of plays and dance recitals, as well as appropriate practice rooms for these performance genres.

The building with classrooms has space for both the Music Division students and the fine arts students. A variety of rooms have been designed for the music students, including lesson rooms, ensemble practice rooms and rooms for the practice of traditional Japanese instruments. In addition, the plans anticipate joint performances by all three grades of the school's Music Division and the new classroom building has a space large enough to serve as a performance venue for these instrumental and choral music performances.

<< Sound Isolation Design >>

Music hall side wall sound diffusing elements
Music hall side wall sound diffusing elements

As mentioned above, currently the school has a quiet surrounding neighborhood. However, the Tokyo Metropolitan government has been building extensions to the No.4 major arterial road (Gaien Nishi Dori) and has plans to further extend it beyond Yasukuni Dori. The extension will result in the road passing immediately to the west of the campus' music hall. According to the information we obtained, the road construction will involve carved out portions of earth and having the roadway built below the grade of the campus. To mitigate sound from this expected future arterial road, on the exterior of the west wall of the music hall we added extruded cement panels as a sound isolation wall.

Architecturally, the entire classroom building has a connected main floor at ground level above which the second through fourth floors rise into four separate wings. This design enabled us to separate the Music Division classrooms from the Fine Arts Division classrooms so that the sounds produced by each of these kinds of study will not interfere with the other students' activities. In addition, within the wings of the building used by Music Division students, we designated the purposes of specific rooms and created an arrangement across more than one wing of the building so that the sound isolation between classrooms is enhanced by physical distance for the practice of genres and instruments that might be hampered if practiced in close proximity.

In addition to using physical distance to mitigate noise transference between classrooms, for rooms requiring a high level of sound isolation we adopted structural anti-vibration and sound isolation measures. Our overall sound isolation design established four levels of sound isolation needs depending on the use of each space and determined which level would be required for each space. In this way, our design successfully balanced the client's desire for both cost savings and effective sound isolation.

<< The Music Hall's Room Acoustical Design >>

The Music Hall seats an audience of 540 persons and is intended for classical music and other acoustical music performances. A plan view of this hall would show that the room has side walls that curve outward. Above the side balconies, white side walls angle inward as they extend up to the ceiling. Together, these architectural design elements create a unique, eye-catching visual interior.

From an acoustical perspective, concave side wall surfaces can be prone to undesirable sound focusing. To prevent this phenomenon from occurring and to promote sound diffusion, we created a wall design that looks as if the side wall surfaces have a repeating pattern of three kinds of pleats, each giving that portion of the wall one of three kinds of angles. In addition, we made the shape of the side walls above the side balconies convex surfaces that reflect early sound reflections back to the audience seating and we also designed the shape of the ceiling into three moderately curved convex surfaces that will reflect sound back to the audience.

When the music hall is used for performances, most-if not all-of the audience seats will be filled. However, when the music hall is used for instruction or as a location for exams, the hall may be used with only a sparse number of people in the audience. For these situations, we added retractable sound-absorbing curtains behind the side balcony seating so that the hall's reverberation time can be adjusted. When the sound-absorbing curtains are retracted, the hall's sound reverberation time measures 2.1 seconds. Extending the curtains along the walls behind the side balcony seating reduces the sound reverberation time to 1.8 seconds (both measured at 500 Hz).

We believe that locating all of the school's students on one campus will stimulate a wealth of creativity and accomplishments by students of all three divisions. We look forward to learning about many new and wonderful artworks and performances by the school's future alumni.

Tokyo Metropolitan High School of Arts' Web site (in Japanese) : http://www.sogo-geijutsu-h.metro.tokyo.jp.


The Right Acoustics for the Music at Ms. Natsuko Yamazaki's "Studio Adelie"

By Dr. Minoru Nagata, Founder of Nagata Acoustics

Studio Adelie

Natsuko Yamazaki's 50 sq. m. (538 sq. ft) piano studio "Studio Adelie" completed on October 25, 2010 in a residential section of Tama City, a suburb located west of Tokyo. In the summer of 2009, at the suggestion of Ms. Taeko Fukuda, formerly of Boesdendorfer, Ms. Yamazaki contacted me and asked for my help with the acoustical design for her new piano studio.

Ms. Yamazaki, who is an accomplished musician, teaches piano and saxophone at her home where she has both a Boesdendorfer Model 225 and a Steinway Model O-180, two grand pianos. Because musical instruments of this quality deserve a concert hall's acoustical environment, I accepted Ms. Yamazaki's request and commenced work on the acoustical design for her piano studio.

<< Acoustical Design for Piano Studio Adelie >>

My acoustical design for the piano studio made use of the natural slope of the terrain below Ms. Yamazaki's home. We dug down 4 m. (13 ft.) and put the floor of the piano studio at 1.2 m. (4 ft.) below entrance level. I specified exterior concrete walls of 200 mm. (8 in.) thick and a sound-isolating system of double-layer products for all externally facing windows and installed double sound proofing doors at the entrance(for bringing in the piano). I also used multiple layers of drywall for the ceiling and interior perimeter walls and for the floor I installed 45 mm. (2 in.)-thick wood laminate supported on a traditional wood substructure. Ms. Yamazaki uses the upper floor of the house as her residence.



Two views of Studio Adelie's interior
Two views of Studio Adelie's interior

Regarding the liveliness of the space, I set the goal of an average sound absorption coefficient of 15 % and achieved this by installing a number of dispersed sound absorbing surfaces on the piano studio's perimeter walls. For the sound-reflecting portions of the room's walls, I specified textured finishes instead of smooth surfaces.

In addition to these acoustical design elements, I focused attention on achieving excellent air circulation, temperature and humidity control in the space to maintain a desirable interior environment for both piano students and the pianos. Asahi Construction Co., Ltd. ably implemented the acoustical design specifications in its role as the project's design-build contractor.

<< Acoustical Characteristics of Piano Studio Adelie >>

At a 1 m. (3 ft.) distance from the piano studio's exterior, the sound isolation performance level measures 57 dB (at 500 Hz), which means that neighbors will not be bothered by any sound disturbance due to sound leakage from the studio. Also, the level of sound isolation inside the studio adequately mitigates any concern about noise from the cars and light commercial vehicles that sometimes travel on the street in front of Studio Adelie.

For heating, cooling, air circulation and humidity control, the studio has a Desica Daikin-brand HVAC unit and a ceiling fan. The noise from this equipment varies depending on the settings in use. The loudest noise level measures NC-30 and the equipment can be run at settings that keep the noise level below NC-25.

Reverberation time (graph) and Average sound absorption coefficient (chart)
Reverberation time (graph) and
Average sound absorption coefficient (chart)

During a typical lesson, with both pianos installed in the room, the studio's reverberation time and average sound absorption coefficient have the values shown on the accompanying graph and chart.

<< Concluding Thoughts >>

In my experience, three considerations determine the acoustics of a home music studio. The first factor is the available space and, in particular, obtaining a sufficiently high ceiling. The second consideration is the musical preferences of the musician who will use the space, because this determines the needed parameters of sound volume and qualitative aspects of the room acoustics. Thirdly, goals must be set to mitigate noise and vibration, including addressing how air circulation and HVAC equipment affect the room's quietness.

Working within the known constraints of the Studio Adelie project, I feel that the ideal acoustics have been achieved for this piano studio. During the construction implementation, the client, Ms. Yamazaki, demonstrated excellent understanding and support for the acoustical design and Mr. Takashi Tanaka of Asahi Construction, as well as all of the construction vendors, contributed significantly to the project's success. I sincerely want to thank everyone who participated on the project.

Studio Adelie is available as a rental practice space for professional musicians. For additional information about renting the space, please contact Ms. Yamazaki directly at +81-42-371-7127.


My Retrospective on Building 1/10 Acoustical Scale Models - Part 3:

The Model a Client Preserved (Nippon Steel Corporation's Kioi Hall, 6/1993 - 9/1993)

By Nobuyuki Ebihara

Because I build 1/10 acoustical scale models, some people think I understand the science of acoustics. Sometimes I'm asked, "What makes a concert hall have fine acoustics?" Being asked this question makes me a bit uncomfortable. My role is the construction of the model used for acoustical testing. To me, sound and acoustics are abstract concepts well beyond my layman's ability to analyze.

Nevertheless, if pressed for my opinion on this topic, I tell people that when I sit in a concert hall and listen to a concert, I should be able to close my eyes and hear "rich" sound that seems to create and fill a larger space than the physical dimensions of the hall I see when I again open my eyes. Also, I should experience a sense of connection with the performing musicians so that the music's tone colors seem to gently envelop us into a single whole.

In a hall with fine acoustics, I can hear the sound of an instrument's quietly quivering string like a sigh I can almost touch. Kioi Hall is this kind of hall.

external appearance of the model
External appearance of the model

Inside view of the model
Inside view of the model

<< Building Kioi Hall's 1/10 Acoustical Scale Model >>

The late Mr. Shin-ichiro Kan recommended me to the Kioi Hall project team and the team hired me to build the hall's 1/10 acoustical scale model. (For more about how I came to know Mr. Kan, see Part 2 of this article series in the February, 2012 issue of Nagata Acoustics' monthly newsletter.) I built the model at a Nippon Steel R&D Laboratory located in Kimitsu City, Chiba Prefecture. The Laboratory had a very large campus and, in one corner of an empty warehouse building so large it could easily hold a soccer field, I unobtrusively built Kioi Hall's 1/10 acoustical scale model.

From the start of my work on this model, the project team included me in various meetings. At first, I thought that I would find these meetings intimidating. The participants included representatives from Nippon Steel Corporation (the owner), the architect and the acoustical consultant (Nagata Acoustics). When I joined the meetings, I discovered that all participants treated everyone equally and in this collegial work environment I made great strides in my productivity and the quality of my work.

Kioi Hall's architectural design was neither ostentatiously unique nor stodgily old-fashioned. At a certain point during the 1/10 acoustical scale model's construction, I began to get the feeling that I could already hear how the acoustics in this hall would sound.

Replicated tiny architectural details
Replicated tiny architectural details

1/10 scale seats
1/10 scale seats

In the positive environment of the overall project, my work on the model progressed rapidly. I was grateful to Mr. Kan for having referred me for the project and I wanted to show my appreciation by building an exceptionally accurate 1/10 acoustical scale model. I replicated even tiny architectural details such as fine slits in the paneling and the shapes of moldings that would be used in hall. I later learned from a Nagata Acoustics engineer that some crevices I created in my zealous attention to detail had been found to absorb an inordinate amount of high frequency sound. To adjust the sound absorption in the model, sealant needed to be painted over the crevices. I regret having caused the need for this extra, remedial work .

<< A Painstaking Interior Element and Adopting a "Craft in My Shop, Assemble On-site" Process >>

For the Kioi Hall 1/10 acoustical scale model I used plywood to make 1/10 scale seats for the model's audience seating area. I made each seat individually, matching the seatbacks' curve to the specification of the seats that would be installed in the real hall. (To make the horizontal portion of each seat, I used a jig and shaved the wood with a router. The router's strong and repetitive vibration made my fingers injured known as vibration white finger. My fingers tingle for months after completing the seats.)

Starting with this project I changed my work process to crafting and fabricating sections and parts of the model in my own shop and then assembling them modularly at the 1/10 acoustical model's location. After making the balcony and the walls' sound diffusing elements off site, I attached them to the wall sections for the model, and then transported this module as well as the ceiling module to the site of the 1/10 model. In the warehouse building where I would assemble the modules, I arranged the modules along a wall before starting to assemble them. Seeing the parts of the model lined up in a row, I momentarily imagined I was in a museum looking at art objects by the likes of Marcel Duchamp. Alone in the space, I held this image in my mind, smiled and savored it.

<< Why Owners Don't Preserve the 1/10 Models >>

A 1/10 acoustical scale model encapsulates all of the rewarding and sometimes challenging work that a hall project's team puts into designing and building a hall. Nevertheless, once the real hall opens, most hall owners dismantle and dispose of their models. It would be easy to think that they should keep them. But, the models take up a large amount of space (typically as much as 25 sq. m. (270 sq. ft.)) and an owner usually cannot justify the expense of relocating the dismantled model, rebuilding it and preserving it. Kindly someone suggested me that I convert a 1/10 acoustical scale model into a private listening room or a child's study room, but I would not be in favor of these or probably any other repurposing idea.

I do take pleasure in knowing that one of the many 1/10 acoustical scale models I built has been preserved. The still-standing model happens to be the model of Kioi Hall. Apparently, after the acoustical testing completed, the model continued to be used for interior design, lighting and other mockups. If the opportunity presents itself, I'd like to go see this model again someday.

People often tell me that it must be disheartening to have the results of my many hours of hard and sometimes painstaking work dismantled. But I don't see things this way at all. My work contributes to a hall's beautiful acoustics and the acoustics of a hall continue to delight audiences now and for many years after the model is long gone.



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

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2130 Sawtelle Blvd., Suite 308
Los Angeles, CA 90025, U.S.A.
Tel: +1-310-231-7878, Fax: +1-310-231-7816

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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 ]