Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 11-10 (No.286)

Issued : October 25, 2011

[ Japanese Version ]

Kunitachi College of Music New Building No. 1

By Fumiaki Sakamaki

Building exterior showing the terraced roof
Building exterior showing the terraced roof

The substantial construction completion of Kunitachi College of Music's new Building No. 1 took place in May, 2011 and the college was able to begin full use of the building this past September. The college's large campus, located at a 5-minute walk from the Seibu Haijima and Tama Monorail lines' Tamagawa-josui Station, now has 6 buildings for instruction and music practice, as well as a large and small hall. Due to the wear and tear of the old Building No.1, the college decided to replace it with a new building on land immediately to the south of the old structure.

<<Building No. 1's Programming, Structure and Project Participants >>

When the programming phase of the replacement for Building No. 1 began, Nagata Acoustics was already participating in a Kunitachi College of Music planning initiative named the "Forming Small Spaces for Music Project". This initiative's participants included a professor from each music discipline taught at the college. The professors reviewed mock-ups of possible future classroom sizes and information about the mock-ups' acoustical characteristics with the goal of understanding what room configurations would be best for a new school building. When the replacement Building No. 1 completed in May, the interior spaces reflected the compiled professors' input and insights gained from the planning initiative.

The replacement Building No. 1 has 3 studios for rehearsals and practice (one each for orchestral, choral and opera music) and 12 rooms of various sizes for ensemble use (including a room for percussion ensembles and electric organ). In addition, on the basement level and on floors 1 through 4, the south side of each floor has music lesson rooms, for a total of 108 music lesson rooms.

The building also has a terraced roof that rises in steps from south to north. The roof's landscaped lawns have rectangular benches placed in parallel to create a pattern that resembles the proportions of the white and black keys of a piano. The planners of Building No. 1 intended this outdoor garden to be a place where students can find calm and relaxation.

The project's structural engineers adopted an energy dissipation seismic design for this building in order to provide safety for the music college's pianos and other instruments. MHS Planners, Architects & Engineers designed the building and was also the construction manager. Shimizu Corporation served as the general contractor. Nagata Acoustics was the acoustical consultant, providing room acoustical and sound isolation designs for rooms throughout the building as well as sound system designs for the 3 studios and overall acoustical design implementation oversight during all phases of the project.

Floor plan of the building's first level
Floor plan of the building's first level

<< Sound Isolation Design >>

Part of our sound isolation design for the building included placing the lesson rooms in the south part of the building separate from the studios and ensemble rooms that are on the north side. To the extent possible, we refrained from locating key rooms directly above or below each other.

In addition, based on what we learned from the school's professors in the "Forming Small Spaces for Music Project", we set a sound isolation objective of 60 dB (at 500 Hz) between lesson rooms. For adjacent lesson rooms on the same floor we used a layer of fixed sound isolation walls plus an anti-vibration and sound isolating layer to achieve the project's sound isolation goal. Between floors we specified concrete slabs and glass wool floating floors. On the roof, below the landscaping and roof exterior, we installed water resistant, high density foam underlayment so that when students walk in the rooftop garden the vibration of their footsteps will not transfer to the rooms directly below.

Music lesson room
Music lesson room

<<Room Acoustical Design of the Lesson Rooms >>

As the phrase "lesson room" implies, the college uses the rooms on the south side of the building not for music practice by students, but for student instruction by professors. Each room has an area of about 30 sq. m. (98 sq. ft) and a ceiling height of 3.5 m. (11.5 ft), making these rooms spaciously sized for their intended purpose.

The results of the "Forming Small Spaces for Music Project" indicated that the professors preferred the lesson rooms to have longer reverberation times than might usually be planned for this kind of room. Our room acoustical design implemented these results and also gave increased priority to obtaining sound diffusing elements on the rooms' ceilings and walls and to the importance of obtaining the appropriate level of low frequency sound absorption. To achieve these goals, our interior design of the lesson rooms starts with the rooms being basically sound reflecting spaces.

From the starting point of a basically sound-reflecting space, we added the following design elements to the music lesson rooms:

  • To prevent flutter echoes, we angled each of the ceilings and walls and we shaped these surfaces to promote sound diffusion.
  • To absorb low frequency sound, we installed 30 cm. (12 in.)-thick glass wool behind perforated metal panels along portions of the ceiling near each room's side wall.

In addition, mid-way between the floors and ceilings of the music lesson rooms' side walls we installed perforated panels, using a visual motif inspired by the five horizontal lines of music paper. Behind these perforated panels, with inserting composite board or glass wool to adjust reverberation time. Additively, professors can attach the sound-absorbing panels using magnets and hooks to increase the sound-absorbing characteristic of a lesson room's acoustics. Examples of the kinds of music instruction that will use this means of increasing lesson rooms' sound absorption include piano, string, wind instrument, voice and electric organ. The sound-absorption panels have brightly colored surfaces that add a cheerful visual accent to the overall white interior tones of the music lesson rooms.

<< Adjustments to the Initial Lesson Room Acoustical Design >>

During the construction phase of the project, we built 3 mock-ups of lesson rooms in the new building's basement level. We used these mock-ups to verify the levels attained by our sound isolation strategy and the reverberation times our room acoustical design achieved. We also asked each department of the college to perform in the mock-ups and for the professors of each discipline to confirm the lesson rooms' acoustics.

The professors' responses to hearing the lesson room acoustics in the mock-ups ranged from "exactly right amount of liveliness" to "as a space where students work to improve their skill, a shorter reverberation time would be better". Each professor voiced an opinion, increasing our insight into the faculty's reverberation time preferences. As a result of the professors' comments, we slightly increased the surface area of the permanent sound-absorbing portions of the music lesson rooms' side walls.

<< Commemorative Master Class Series and the Start of the Fall Semester >>

Orchestra rehearsal studio
Orchestra rehearsal studio

In late August, Kunitachi College of Music sponsored a master class series to commemorate the completion of the school's new Building No. 1. The college invited well-known musicians from around the world to teach in the new building's studios and the ensemble rooms, and the college opened attendance at the master classes to both Kunitachi College students and non-students as well. Many musicians came to the college to attend the master classes, eager for the opportunity to learn "up close" from some of their favorite international virtuosos.

In September, with the start of the fall semester, instruction in the new Building No.1 began in earnest. The energy of the young music students now pervades the lesson rooms and hallways of the new building. We hope that the student body will make the most of this new facility and achieve their potential as the musicians of tomorrow.

The Kunitachi College of Music : http://www.kunitachi.ac.jp/.
Photos by Kawasumi Architectural Photographer

Jissen Gakuen Junior & Senior High Schools' New Freedom Learning Manor House Opens

By Toshiko Fukuchi

Freedom Hall
Freedom Hall

The history of Jissen Gakuen Junior and Senior High Schools dates back to the 1927 establishment of Tokyodo Kyoshujo School in the Kanda Nishikicho section of Tokyo. Some years later, the school changed its name to Jissen Gakuen and, in 1942, moved to its current campus in the Tokyo suburb of Nakano City.

Now in its 85th year, the Jissen Gakuen Junior and Senior High Schools offer innovative academic curriculums and teaching methods, and the schools pride themselves on the progressive design of their campus' physical environment and facilities. In keeping with the schools' focus on innovative learning environments, in April of this year, the school opened its new Freedom Learning Manor House. Waseda University Professor Nobuaki Furuya and his STUDIO NASCA architectural firm designed the new structure.

<<Architectural Highlights of the Project >>

The Jissen Gakuen Junior and Senior High School campus is located on a site that is a 5-minute walk from the Nakano-sakaue Subway Station. The new Freedom Learning Manor House is within easy walking distance of the school campus. Freedom Learning Manor House stands in the midst of a residential neighborhood, with the greenery of Miyamae Park adjacent to the west, Momozonogawa Greenway adjacent to the north side of the property and houses nearby.

Freedom Hall's concrete wall surface, designed to have protrusions and indentations
Freedom Hall's concrete wall surface
designed to have protrusions and indentations

Freedom Learning Manor House has a 350-seat Freedom Hall on its lowest level, which is a combination of a below-grade half-basement and a first floor. Part of the building's second and third floors is used for a "Learning Terrace" that is an atrium-like space, with the third floor overlooking the second floor space. The Learning Terrace combines the functionalities of a library and study space. In addition, the building has other study and instruction rooms.

The intended uses of Freedom Hall require effective sound isolation and, therefore, this part of the building needed to be partitioned from the rest of the space. However, the second and third floors of the building have an open plan design without columns. The staircase between these two levels is also integrated into the open plan design. Because these two floors are not obstructed by thick columns and because glass windows extend across large portions of the exterior walls, the building interior feels very spacious. In particular, the desks in the Learning Terrace face towards Miyamae Park so that when students need a quick respite from their studies, they can simply look out the windows and enjoy the natural scenery outside.

The Freedom Learning Manor House exterior has a low overall height and the roof appears to be gently perched or almost float on the building's walls. This design blends well with the nearby and residential architecture by not having an overpowering presence.

<<Acoustical Design of Freedom Hall >>

Freedom Hall has a 5 m. (16.4 ft) high ceiling, a mostly rectangular footprint and retractable seating. The seating apparatus is attached to the rear of the seating area where it is stored. With the seating retracted, the flat floor hall provides ample space for chorus practice and a variety of other uses.

The hall's exact footprint widens slightly towards the front of the hall. The lower portions of the side walls are finished with a random pattern of 3-dimensional ribbing partially backed by sound absorbing material. To obtain a ceiling surface that is not parallel with the floor, the ceiling design has angled panels. The ceiling panels are made of both sound reflecting and sound absorbing surfaces. We worked closely with the architect to together develop this design solution. It both implements the architect's concept for the hall interior and uses the acoustical design elements needed to successfully prevent flutter echoes.

Another result of our collaboration with the architect can be seen in the concrete wall surface on the upper portion of the wall behind the hall stage. To soften sound reflections from this surface, the design has an uneven surface of protrusions and indentations. Making the forms for this kind of uneven concrete wall required painstaking work on the part of the construction crew.

Freedom Hall also has glass surfaces on the upper portions of the side walls. To prevent sound from leaking through the frames of the glass panels, we specified wide double frames for each of the glass side wall sections. After the completion of construction, we took measurements to check the performance level achieved by this sound isolation strategy and found that we successfully met our objectives. The client also reported that the hall performs as expected during actual use of Freedom Hall. Because Freedom Hall is partially below grade, the large glass surfaces of the side walls bring natural light into the hall to create an appealing indoor environment.

On May 14 and 15, 2011, the school held an opening ceremony for Freedom Hall. Neighborhood residents came to see the facility as well as students and others associated with the school. Freedom Learning Manor House has earned quick popularity as a place to study among with the school's students. Its innovative architectural design will surely sustain its popularity for many years to come.

The Jissen Gakuen : http://www.jissengakuen-h.ed.jp/index.php.

1/10 Scale Model Testing for Osaka New Festival Hall

By Nobuhiko Hattori


As construction towards the spring, 2013 opening of Osaka's Nakanoshima Festival Tower skyscraper moves forward on schedule, Nagata Acoustics' work on the project's featured New Festival Hall portion of the project also continues at a steady pace. Milestones for the hall's basic architectural design and acoustical computer simulations completed in previous phases of the project and for a 6-month period from the summer of 2010 through the winter of 2011, we performed testing in a 1/10 scale model.

<<Summary of the New Festival Hall Project >>

Like the old Osaka Festival Hall that it replaces, the New Festival Hall, a multipurpose hall with 2,700 seats and a proscenium stage, will be used for a broad range of purposes, including classical music concerts, opera, popular music concerts and other performing arts genres. On the acoustically significant, sound-reflecting ceiling and side wall surfaces, the design of the new hall's interior incorporates the same kind of ribbing on the ceiling and the same kind of sound diffusing side wall elements that were hallmarks of the old Osaka Festival Hall and its acoustics. The New Festival Hall will have a stage sound reflection panel system and an orchestra pit, which the old Festival Hall also had. A new feature will be side stage wings that can be deployed or stored.

The design-build project's architect and general contractor is Nikken Sekkei. Mr. Nobuyuki Ebihara(a carpenter), who has built many scale models for our projects, constructed the New Festival Hall 1/10 scale model.

Audience seating area
Audience seating area

<< The 1/10 Scale Model Testing >>

The main activities and objectives of our testing in the 1/10 scale model included:

  • Emitting sound in the model and then measuring the impulse responses and verifying consistency between the model's results and results from our computer simulations;
  • Verifying the reach of reflected sound; and,
  • Listening inside the model to check if the design produces any echoes.

For additional information about how and why we test in 1/10-scale models, see our February, 2007 newsletter.

To meet the needs of the various performance genres that will use the New Festival Hall, this multipurpose hall will offer several different possible stage configurations for the different acoustical conditions and requirements needed depending on the performance genre. We tested 3 representative configurations in the 1/10 scale model, including a configuration for classical music concerts (with the sound reflection panel system set up on stage, the orchestra pit covered and the side wings in place), a configuration for opera (with the orchestra pit exposed and both sound reflection panel system and side wings stored) and a configuration for popular music (using proscenium and other loudspeakers as the sound source).

<< Testing How Ribbing and Sound Diffusing Elements Affect the Hall's Acoustics >>

On this project, the design of the acoustically important stage sound reflection panel system, ceiling, side wall, and the sound diffusing elements (needed to generate abundant sound reflections and distribute them evenly throughout the hall) came under intense scrutiny during the design phase. Therefore, in addition to the above tests in the 1/10 scale model, we also tested the acoustical effect of each of these design elements to confirm how they contribute to the sound reflections and their even distribution throughout the hall.

To perform validations of the effect of the ribbing and sound diffusing elements, we began with a scale model interior that had smooth wall and ceiling surfaces. One-by-one, we added ribbing to the ceiling and diffusing elements to the side walls, while measuring how each change in the scale model's interior affected the acoustics.

When the model's interior had smooth surfaces, we heard sharp sound reflections that separated in various directions inside the model. When we added sound diffusing elements to the walls, we were able to confirm with our own ears that the sound reflections increased and individual reflected sounds coalesced into the kind of full bodied sound we aimed to achieve.

<< The Precision of the 1/10 Scale Model >>

It may be difficult for readers to easily know if a 1/10 scale model of a concert hall is large or small. Concert hall 1/10 scale models are large enough for an adult to stand inside and the 1/10 scale model of the 2,700-seat New Festival Hall provides an impressive sense of the large size the new hall will have.

From the curved, 3-dimensional surfaces of the new hall's ceiling to the sound diffusing elements that in the model each measured 10 sq. cm. (4 sq. in.), to the storable side wings, the model replicates in 1/10 scale every part of the hall's interior design and all its movable parts as well. Building the model requires great care, talent and precision. We use the 1/10 scale model as a valuable tool for acoustical testing. Other project participants also use it to consider various architectural details and to confirm the sight lines from audience seats to the stage.

Festival hall : http://www.festivalhall.jp/

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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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 ]