Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 13-08 (No.308)

Issued : August 25, 2013

[ Japanese Version ]

The Harmony Hall (Matsumoto Music Culture Center) Renovation Project

By Dr. Keiji Oguchi

Matsumoto City and classical music have strong ties. The association for the famous Suzuki Method of music instruction has its headquarters here and the Saito Kinen Festival draws classical music fans to this picturesque city every summer.

The city sponsored the building of Harmony Hall, which opened its doors for the first time in 1985, to create a local destination for music culture. Two years after the hall's opening, a 40-stop pipe organ was installed. When Nagata Acoustics published our first newsletter three months later (in January, 1988), the first issue included an article about Harmony Hall and its pipe organ. The article introduced the unique operation of the hall by the producers, the resident organist and the attentive user groups, and noted that this hall has an atmosphere that are decidedly unlike those of the average civic hall. Today the hall continues to have the same special atmosphere.

Ceiling support structure before renovation
Ceiling support structure before renovation

<< The 2011 Earthquake Damage >>

On June 30, 2011, two and one-half months after the 2011 off the Pacific Coast of Tohoku Earthquake struck on March 11, an aftershock of an intensity of 5-plus shook Matsumoto City, injuring residents and causing property damage. The earthquake damaged the ceiling of Harmony Hall's main hall and the city had no choice but to close the facility for repairs.

Looking at the ceiling from inside the hall, the ceiling damage appeared to be a narrow crack, but investigation in the space above the ceiling revealed ruptures in the ceiling structural support system. To prevent the possibility of a future ceiling collapse, the decision was made to replace the entire ceiling. The city decided to maximize the benefit of the hall's temporary closure and added to the project replacement of the audience seating, full upgrade of the sound system, replacement of the floor in the audience seating area, renovations around the stage and various aesthetic enhancements.

<< Seismic Improvements to the Hall Ceiling >>

Earthquake-resistant ceiling support structure
Earthquake-resistant ceiling support structure

Ceilings of large-scale indoor spaces such as gymnasiums and concert halls typically have a ceiling structural design known as “suspended ceiling” in which the ceiling is attached to vertical metal hanger rods. In conjunction with this kind of design, space is intentionally created between the roof and the ceiling so that HVAC and lighting equipment as well as heating insulation and acoustical material can be installed, out of sight, in this space.

When an earthquake of the strong intensity felt in 2011 strikes, a suspended ceiling will swing back and forth, putting unintended forces on the hanger rods and the entire ceiling support system. In the worst case scenario, the entire ceiling might collapse.

The seismic retrofit design for Harmony Hall's hanging ceiling included two key elements. One element was the creation of structural system that allows only a minimal amount of sway. The second element was to add separations between the ceiling and side walls as well as between parts of the ceiling so that, if an earthquake strikes and the ceiling moves, it will not collide with the side walls or other parts of the ceiling structural system.

<< Achieving the Dual Goals of Earthquake-Resistance and Fine Acoustics >>

For this renovation, preserving the hall's highly regarded acoustics was as important as the seismic retrofit. The project team defined the following plan to achieve these dual goals:

  • Because the heavy ceiling plays a significant role in the acoustics of the hall, use the same material used in the original hall. The material is a double layer of fiber-reinforced gypsum board. The thickness of the double layer is 24 mm (1 in.).
  • In the space above the ceiling, install a new structure frame for hanging ceiling located close to the ceiling and use short hanger rods to suspend the ceiling.
  • Design and develop new metal fittings for the complex needs of the hanging ceiling that has angled panels. Specifically, add braces to secure the lightweight gauges to screw angled pales.
  • To prevent parts of the ceiling from impacting other parts of the ceiling, secure the inner and outer corners of the angled parts of the ceiling. Also to prevent parts of the ceiling from impacting the side walls, create separations that restrict the possibility of interaction between the ceiling and the side walls.
  • Cover the separations between the ceiling and the side walls with soft damping sheets of 2 mm. (0.08 in.) thickness.

<< Matching the Absorption and Reverberation to the Original Hall's Characteristics >>

Hall interior
Hall interior

As part of the renovation project, we replaced all Harmony Hall's original seats with new, wider seats resulting in a decrease in the total number of seats from 756 to 693 seats. From the perspective of fixed absorption in the hall, the reduced number of seats represented a reduction of absorption while the separations created at the ceiling edges for seismic retrofit represented an increase.

To achieve the goal of “no change to the hall's acoustics”, we carefully considered the renovation changes that would affect absorption in the hall. We tested the absorption of the new audience seats and calculated the effect of the separations at the ceiling edges. We finally concluded to change the portion of the ceiling that in the original hall finished with perforated board to instead finish with the same double-layer board as the rest of the ceiling.

Our design succeeded in achieving about the same reverberation time in the renovated Harmony Hall as in the original hall. The wood backs of the new audience seats create the result that the renovated hall's acoustics have increased clarity compared with the original hall, a change that has generated only positive comments. I'm confident that the renovated Harmony Hall will become even more beloved by its patrons in the years to come.

Piano Practice Room in the Residence

By Toshiko Fukuchi

Piano practice room(1)
Piano Practice Room(2)
Piano Practice Room Interior

In January, 2013, construction completed in Fujieda City, Shizuoka Prefecture on a piano practice room designed for use also as a concert space.

The client's home is a 3-story, reinforced concrete structure. The upper two floors have the family's living space and the ground floor level has the 27 sq. m (291 sq. ft) piano practice room. In addition to individual use of the ground floor space for piano practice, the client specified that they also plan to invite friends to the new space for private concerts. For this reason, the ground floor has a separate entrance from the residential living space, as well as its own kitchenette and washroom.

Mr. Eiichi Sugiura of Eiichi Sugiura Architect & Associates provided the architectural design for the project and Shizuoka City-based Goko Construction Co., Ltd. served as the general contractor. The client began the project by selecting Mr. Sugiura as the project architect because Mr. Sugiura's work on other upscale residential projects impressed the clients greatly. Mr. Sugiura requested our help on the project for the space that would be used as the piano practice room and concert space.

In the role of Acoustical Consultant, we identified the following sound isolation and room acoustics goals for the project:

  • Prevent the transfer of sound from the piano practice room to the upper level living spaces and from the piano practice room to neighboring homes;
  • Isolate the piano practice room from nearby street traffic noise and from heating and ventilation noise; and
  • Create fine room acoustics, especially for the performance of piano music.

<< Sound Transfer and Sound Isolation Designs >>

Initially, to prevent the transfer of solid-borne sound from the piano practice room to the upper levels, we considered using a floating floor in the piano practice room. However, because the piano practice room is located on the ground floor, we decided instead to provide this sound isolation by increasing the thickness of the ground floor's concrete slab.

We focused on the building's heating and ventilation ducts as the most likely path for sound to leak outside the piano practice room and be audible at neighbors' homes. We both eliminated this concern and addressed the need to mitigate noise from the heating and ventilation system inside the piano practice room by installing elbow-shaped HVAC duct silencers at each air supply and exterior louver of the system.

To isolate the practice room from street and traffic noise, we used different thicknesses of double-glazed glass and single pane glass for the operable and non-operable portions of the room's windows. At the completion of the project's construction, we confirmed that the sound of piano playing cannot be heard on the upper levels or outside. We also successfully kept the piano practice room quiet and free of heating and ventilation noise. As for noise from the nearby street's traffic, only very low frequency sounds can be occasionally heard.

Tilted side wall
Tilted side wall
Ribs on the side wall
Ribs on the side wall

<< The Piano Practice Room's Acoustics >>

In general, if a small-scale piano practice room has a long reverberation time, the sound saturates the room and impedes effective practice. However, when a practice room has a short reverberation time, pianists also often report that this condition of a room's acoustics makes practice difficult.

The basic dimensions of this project's piano practice room measure 4.5 m (15 ft) × 6 m (20 ft), with a ceiling height of 3 m (10 ft) and room spatial volume of 80 m³ (2,830 cu. ft), for an overall space of modest size. To prevent the space from being saturated by overly large sound volume, as well as to prevent undesirable sound phenomena such as flutter echoes or muffled low frequencies, we tilted the walls to appropriate angles (both when viewed in a plan view and in a cross-section view). In addition, to promote scattering of sound reflections, we placed ribs of between 45 mm (2 in.) and 105 mm (4 in.) depth at random locations on the room's walls. We installed sound-absorbing materials only sparingly on specific parts of the ceiling and the walls.

Upon completion of the practice room's construction, in addition to the client trying out the new hall by playing the piano she installed there, the client also requested some young friends who currently study at Tokyo Geijutsu Daigaku (Tokyo University of the Arts) to perform in the new space. The friends' performances afforded our client the opportunity to experience the space from the perspective of a concert audience listener.

After the test performances, the clients expressed their delight and satisfaction with the acoustics, both as performer and listeners. The students added comments that the acoustics sounded fuller and better than they expected from the modest dimensions of the space and that they would like to perform in the space with a chamber music ensemble. From my own listening evaluation, I was pleased when the large sound of a Liszt composition did not overwhelm the room. I also felt that the acoustics have greater expansiveness than might be assumed from the way the space looks visually.

Elated with the results of the project, the client plans to hold concerts in the new space as well as use it for piano practice. For this writer, on this residential project I reaped a bounty of personal enjoyment different in many ways from the professional satisfaction of participating on large concert hall projects.

Paris' Île Seguin “Cité Musicale” Project Competition Results

By Dr. Yasuhisa Toyota

A competition held to select the design-build team (including the architect, engineer, construction company and acoustical consultant) for “Cité Musicale”, a new mutli-facility complex planned on Paris' Île Seguin (Seguin Island) completed with the joint venture of the design team (Japanese architect Mr. Shigeru Ban) and the construction team (Bouygues) being awarded the project. Design and construction of the project will now soon commence towards the goal of project completion and opening of this new center for the performing arts.

For some decades prior to 1992, the automotive manufacturer Renault used the entire Seguin Island as the site of its manufacturing plants. In 1992, the company moved all of its manufacturing elsewhere and closed the manufacturing facilities on the island. Thereafter, architect Jean Nouvel became the consultant charged with developing a new master plan for the island. In June, 2010, Mr. Nouvel unveiled his plan for a “Cité Musicale”, which includes a concert hall and large-scale multipurpose hall among the new facilities.

After Mr. Nouvel completed the master plan, the work of formulating a concrete development plan was entrusted to a private finance initiative (PFI) and a competition was held among three groups, each of which had an architect's proposal at its core. Nagata Acoustics participated on the design team led by Shigeru Ban Architects Europe and Jean de Gastines Architectes. The entire team was organized and led by the global construction firm Bouygues Batiment IDF. The team succeeded in winning the competition and being awarded the project.

“Cité Musicale” will have a multipurpose hall with 4,500-6,000 seats and a classical music concert hall with 1,150 seats, plus rehearsal rooms and music training facilities under the auspices of the Paris Opera, as well as restaurants, shops, housing for orchestra musicians and other amenities. The large scale undertaking will cover some 36,500 m² (9 acres) and has a projected construction budget of 177 million Euros. Ground-breaking is scheduled for March, 2014, completion of construction in June, 2016 and the opening of the halls in October, 2016.

Rendering of planned Cite Musicale exterior on Ile Seguin
Rendering of planned “Cité Musicale” exterior on Île Seguin

Rendering of the multipurpose hall interior
Rendering of the multipurpose hall interior

Rendering of concert hall interior
Rendering of concert hall interior

(Photos courtesy of Shigeru Ban Architects Europe and Jean de Gastines Architectes)

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

[ Japanese Version ]