Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 10-07 (No.271)

Issued : July 25, 2010

[ Japanese Version ]

Kita-ku Cultural Center Opens in Niigata City

by Fumiaki Sakamaki

Kita-ku Cultural Center building exterior
Kita-ku Cultural Center building exterior

Kita-ku Cultural Center ground level floor plan
Kita-ku Cultural Center ground level floor plan

In June, 2010, Kita-ku Cultural Center opened in Niigata City. Kita-ku is located about 20 minutes by train from Niigata Station (the northernmost station of the Joetsu Bullet Train Line). From Niigata Station, visitors to the new cultural center can ride the JR Hakushin Line to Toyosaka Station and then walk to the new cultural center. The walk from Toyosaka Station takes about 15 minutes.

In 2005, Toyosaka City merged with neighboring Niigata City. Two years later, in 2007, as part of Japan's governmental designation of 13 municipalities that have populations greater than 500,000, the area previously named Toyosaka City became incorporated into Niigata City's Kita-ku, becoming the central portion of Kita-ku.

<< Overview of Kita-ku Cultural Center >>

The main facility in the new center is the 549 seat hall, which I will introduce in detail later in this article. In addition to the hall, the center has four practice rooms designed for a range of music genres, other performing arts and the Japanese tea ceremony. The first practice room, which accommodates up to 100 persons, can be used as a small hall as well as for practice and rehearsals. The second practice room is appropriate for choral and dance rehearsals and practice. The third practice room is acoustically designed for large volume sound and is intended for electric instrument practice. The fourth practice room has tatami mat flooring and is intended to be used for the traditional Japanese instruments, the Japanese tea ceremony and the traditional Japanese dance genres. In addition to the hall and these four practice rooms, the cultural center also has a conference room, a childcare facility, dressing rooms for performers and other ancillary rooms.

The center's layout has all of the main facilities on the ground level, including the hall and the four practice rooms. The architectural design uses glass wall surfaces abundantly for the practice rooms, the center's foyer and generally throughout the structure, giving the building a bright and open feeling.

The firm of MHS Planners, Architects & Engineers developed the architectural design of the cultural center building. General contractors Honma Corporation, Kondo Gumi Co., Ltd, and Shimazu Gumi jointly built the center through a consortium agreement.

<<Sound Isolation Design >>

Because the practice rooms are located around the perimeter of the main hall and in close proximity to it, our acoustical consulting on this project included providing an effective sound isolation strategy between the practice rooms and the hall. Our design implemented anti-vibration structural designs for the first, second and third practice rooms. In particular, because the project's programming anticipated simultaneous use of the hall and the first practice room, and because we planned the third practice room to accommodate music that generates large sound volumes, we adopted especially robust sound isolating structural designs for these two rooms.

Specifically, for the structural design of the first and third practice rooms, we began with a foundational layer of anti-vibration rubber material and built freestanding steel framing for each room above the anti-vibration layer. Additionally, we used extruded cement boards to create sound-isolating structural elements between the rooms. For the anti-vibration and sound-isolating structural design of the second practice room, we used an anti-vibration rubber material and a floating floor structural design together with triple layers of 8 mm. mixed fiber gypsum board.

The first and third practice rooms have glass walls on the sides of these rooms close to the hall. For these walls, we specified three glass layers comprised of one floating sound isolation glass layer and two fixed sound isolation layers. These two practice rooms also have glass walls on the sides of the rooms that face the building exterior. For these glass walls, we specified double glass layers, comprised of one floating sound isolation glass and one fixed sound isolation layer. Our design achieved sound isolation for sound volumes greater than 90 dB (at 500 Hz) between the hall and the first and third practice rooms.

<<Room Acoustical Design of the Practice Rooms >>

Glass walls on the sides of first practice room
Glass walls on the sides of first practice room

The audience seating area of the hall seen from the hall's stage
The audience seating area of the hall
seen from the hall's stage

The first, second and third practice rooms share the key architectural design element of glass walls that face each other across opposite sides of each room. Because parallel, sound reflecting surfaces produce undesirable flutter echoes, in all three of these practice rooms we specified that the glass walls be tilted outward at an angle of between 3 and 6 degrees.

In addition to angling the sidewalls of the first, second and third practice rooms, we specified large-angled slopes for the ceilings of these rooms, so that the floors and ceilings would not be parallel surfaces. Also, to provide the appropriate acoustical characteristics for each of these practice rooms, we located sound-absorbing elements at dispersed locations on the two non-glass sidewalls of each room.

<<Room Acoustical Design of the Center's Hall >>

The project programming for the Kita-ku Cultural Center hall included numerous and diverse uses for the hall, including classical music concerts, symposia and lectures, ceremonies and drama performances, among others. We interpreted these many needs into a multipurpose hall design with a single, sloped audience seating area.

In our acoustical design of the hall, we prioritized creating a space that, in particular, has acoustics well-suited to the performance of non-amplified musical instruments. To this end, we developed a design with a sense of continuity between the stage area and the audience seating area. We created this feeling in the hall by specifying the height dimension of 11.5 m. for the proscenium opening. For the same priority, we also worked to achieve sufficiently generous acoustics in the hall by maximizing the spatial volume of the hall.

The distance from the edge of the stage to the rear of the hall measures a compact 22 m. and, in order to achieve the desired seat-count, the width of the audience seating area measures 24 m. across at its widest point. With these dimensions and the architect's initially proposed sidewall treatments, the center portion of the hall's seating area would not have received sufficient sound reflections from the sidewalls.

To remedy this issue, we revised the portions of the sidewalls near the front of the hall to have a stepped design with sound reflecting elements set at angles that direct the sound reflections to easily reach the center portion of the audience seating area. We also designed an onstage sound reflection panel system and added eave-like elements to the sidewalls to effectively reflect delayed early reflections to the audience seating area.

For times when the hall will be used for non-amplified music concerts, we ensured that the hall will deliver rich acoustics for low frequency sounds by specifying the use of composition board having sufficient thickness and the use of multiple layers. Conversely, when the hall will be used with a stage curtain, the room acoustics need to control and reduce the production of low frequency reverberations. For this purpose, we set glass wool on the back of the stage's wall and created air space behind it. When the sound reflection panel system is not deployed, the glass wool absorbs the unwanted low frequency sounds.

When the sound reflection panel system is in use, the Kita-ku Cultural Center hall's reverberation time measures 1.8 seconds (with the hall fully occupied and at 500 Hz). This configuration also provides rather long reverberation times for low frequency sounds and makes the hall well-suited to performances using non-amplified musical instruments. In addition, when the sound reflection panel system is not in use and the stage curtain is deployed, the sound reverberation time measures 1.3 seconds (with the hall fully occupied and at 500 Hz) and low frequency sounds are effectively reduced to an appropriate level.

<< Kita-ku Cultural Center Hosts Tokyo Vivaldi Ensemble for Its Inaugural Event >>

On June 7, 2010, Kita-ku Cultural Center enjoyed its opening event with a performance by Tokyo Vivaldi Ensemble. Unfortunately, my schedule did not allow me to attend the inaugural performance, which generated such overwhelming interest from the local community that the center resorted to a lottery system for selling tickets.

Looking at the center's Web pages, I can see that the hall already has a busy calendar in July and August, with multiple events planned by local residents. I hope that this cultural center will bring new and increased levels of cultural activity to the residents of Kita-ku and that they will long enjoy using this new facility.

The Kita-ku Cultural Center's website is located at http://www.kitaku-bunkakaikan.com/

Acoustical Building Materials from Around the World: Part 2 - "Acoustic Plaster"

By Dr. Keiji Oguchi

Illustration of vermiculite coated panel on page 288, Building and Acoustical Engineering Sciences Handbook (1964)
Illustration of vermiculite coated panel on page 288,
Building and Acoustical Engineering Sciences Handbook (1964)

BASWAphon Fine
BASWAphon Fine

BASWAphon Fine sound absorbing characteristics (28 mm. thick panel affixed to a concrete layer)
BASWAphon Fine sound absorbing characteristics
(28 mm. thick panel affixed to a concrete layer)

In this installment of my series on acoustical building materials from around the world, I will introduce "acoustic plaster"to readers, especially in Japan. Until the recent past, Japanese builders used an acoustic plastering material made from vermiculite. The 1964 edition of the Building and Acoustical Engineering Sciences Handbook, edited by the Acoustical Materials Association of Japan (published by Gihodo Corporation) contains an illustration, reproduced here, of a sound-absorbing panel coated with a layer of vermiculite.

When heat is applied to vermiculite, the material expands and becomes porous. This property of vermiculite makes it a popular soil additive for gardening.(1) The porous properties of vermiculite also made it useful as a sound-absorbing coating applied during the surface finishing activities on construction projects. However, when vermiculite sourced from certain locations around the world was found to contain asbestos impurities, the use of vermiculite as a sound-absorbing coating was discontinued in Japan for this reason.

<<Acoustic Plaster from Switzerland >>

In Switzerland, BASWA Acoustic AG manufactures an acoustic plaster product on a glass wool base. I visited the company in March of this year and had the opportunity to observe in detail the production of the BASWAphon product.

As its base material, BASWA Acoustics uses a special kind of glass wool that has its glass fibers intertwined in such a way that they do not easily exfoliate. On one side of this glass wool base BASWA Acoustics applies a coating of beads made from recycled glass mixed with a binding agent. After applying the coating, the process allows time for the coating to dry. This step completes the process to produce the BASWAphon acoustic panel.

The BASWA Acoustics process then affixes the BASWAphon acoustic panels to either concrete or drywall surfaces using an adhesive and finishes the surface using a plastering material that contains ground marble, producing sound-absorbing, seamless finished products for large surface area dimensions. Because both the glass beads layer and the plaster layer have sufficient degrees of permeability, the glass wool's sound absorbing properties remain unaffected by these layers.

BASWA Acoustics offers its BASWAphon acoustic panels in three finishes: Base, Fine and Classic. The Classic finish has two coatings of plaster and its surface has a rather smooth appearance even when examined at close proximity.

The sound absorption data for BASWAphon acoustic panels peaks in the mid-frequency ranges and, for even high frequency sounds exhibits a sound absorption coefficient greater than 0.5. These results make it an appropriate finishing material to use on room ceilings and walls for the purpose of controlling excess sound reverberation.

To maintain the design integrity and sound absorption performance quality of its products, BASWA Acoustics offers a training course in implementing them on construction projects. I found this an intriguing approach to quality control for an acoustic plaster manufacturer.

Through some additional Internet searches, I found other acoustic plaster manufacturers in various other countries. Some of these companies include Fellert (http://www.fellert.com), Decocoat (http://www.decocoat.fi/index.php) and Sto (http://www.sto.co.uk/24902_EN-Acoustics-StoSilent_Panel.htm).

* Note: Vermiculite now sold in Japan for gardening purposes does not contain asbestos.

Condos for Music Lovers: Nogata "Musi[c] [Man]sion"

by Akira Ono

Musi-sion Nogata
Musi-sion Nogata

Music salon
Music salon

Nagata Acoustics began providing acoustical consulting services to the design and construction of "musi-sions" (condominiums that target upscale professional and amateur musicians by featuring robust sound isolation) from the inception of this kind of condo development slightly more than a decade ago. The real estate developer who conceived the idea of "musi-sions" combined the English word "music" with "mansion" (the Japanese word for condominium) to coin the now accepted Japanese word "musi-sion" to describe these properties. In the years since we introduced readers to the first musi-sion in Kawagoe, Saitama Prefecture (in our October, 2000 newsletter.), we have consulted on five musi-sion projects, including the recently completed Musi-sion Nogata project, which is the topic of this article.

<< Overview of the Project >>

The Musi-sion Nogata project site is a 5-minute walk from the Seibu Shinjuku train line's Nogata Station, in Nakano Ward, Tokyo. The building faces directly onto Loop Route No. 7, a major vehicular thoroughfare, and is a 6-story, reinforced concrete structure. The property owner, a doctor of psychosomatic medicine, has his clinic and a music salon on the ground level, condominum units (that he plans to rent instead of sell) on floors 2 through 4, and his own unit on floors 5 and 6. The rental unit floors (2, 3, and 4) have 4 units each.

Musi-sion Nogata is a small-scale building with a total of just 12 units, plus the ground floor space and the penthouse unit. In the ground floor music salon, the building owner installed a Steinway piano, and he plans to have both his family and renters of the units on the middle floors use this space.

<< Acoustical Design and Sound Isolation Characteristics >>

Underneath all of the rental units, we implemented a "box-in-box" glass-wool, floating floor anti-vibration and sound isolation structural design. As a result, both between adjacent rooms and between adjacent floors, we achieved sound isolation levels of D-70 (a rating based on standards set by the Architectural Institute of Japan). At this rating level, piano music cannot be heard at all in the adjacent space.

For previous musi-sion projects, we specified single-pane, operable windows because low levels of external noise would beneficially mask the sound of music being played in an adjacent room if the sound managed to leak between rooms. However, the external environment of Loop Route No. 7 generates a large volume of noise and, therefore, we specified double-pane windows for Musi-sion Nogata. Even with this enhanced soundproofing measure, a small amount of vehicular traffic noise leaks into the condominium's rooms.

<< The Developer's and Architect's Dedication to High Quality Design and Construction >>

On this project, real estate developer Livlan Company partnered with Mr. Masahiko Sawamura, a Kyoto-based architect, to design and develop the Nogata property. Mr. Sawamura previously won the Japan Industrial Design Promotion Organization's Good Design Award for his architectural design of Musi-sion Shiki, in Saitama Prefecture.

On our most recent two musi-sion projects, Livlan Company acted as its own general contractor. During construction, the on-site superintendent's attitude could be compared to that of someone producing goods in a company shop that highly values its brand name. Livlan Company believes that its future profitability depends on earning the satisfaction and trust of the property owner and end-users of its current project. Therefore, in addition to the concerns of maintaining a profit margin, the Livlan superintendent focused on delivering high quality construction. Livlan Company addressed Nagata Acoustics' acoustical design specifications and requirements with precision and efficiency, consistently achieving overall high quality and high levels of sound isolation performance.

In Japan's competitive condominium market, developers and realtors try to find some kind of added value to promote, in addition to the basics of easy access to a commuter train station, spacious dimensions, younger building age and affordable rent or condominium feesl The musi-sion projects build units with high-performance sound isolation characteristics using low cost design and construction techniques that successfully balance profitability and design and construction costs, while simultaneously eliminating post-construction claims. With each successive project, Livlan Company applies what it learned on its past projects and brings this know-how forward. These are the key reasons why the musi-sion projects continue to satisfy condo owners and continue to be built.

For more information about musi-sion projects and Livlan Company, visit http://www.musision.com/ (in the Japanese language only).

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 308
Los Angeles, CA 90025, U.S.A.
Tel: +1-310-231-7878, 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