Title means "Quietness", "Comfortable Sound" and "Excellent Acoustics"

Nagata Acoustics News 06-03 (No.219)
Issued :March 25, 2006

Nagata Acoustics Awarded Radio France Concert Hall Project

by Dr. Yasuhisa Toyota

Fig-1 Radio France
The French Radio Broadcasting Corporation, Radio France has selected Nagata Acoustics as the Acoustician for its new concert hall. The new hall will be a 1,500-seat capacity auditorium and Paris' first hall designed specifically for the performance of classical music. The hall will be constructed inside Radio France's existing headquarters, the Maison de la Radio, located near the Eiffel Tower along the left bank of the Seine.

The original construction of the Maison de la Radio building dates back to the 1970s. Its beautifully designed, circular exterior is a Paris landmark of contemporary architecture. Three decades after the Maison's debut, its graceful exterior shows no signs of age, but the structure's interior no longer meets local building code requirements for security and has developed a number of other problems. The planned major renovation project will completely update the inside of the building. Unlike other aspects of the renovation project, however, the current building does not have a big concert hall for orchestral music, so the hall will be an entirely new addition to the facilities.

Radio France conducted an invitation-only competition to choose the Maison renovation project's principal architect, and the local Paris architectural firm Architecture-Studio (http://www.architecture-studio.fr) submitted the winning proposal. After this step, Radio France convened an internal committee charged with implementing a selection process for the new concert hall's Acoustician, a process that culminated in the committee naming Nagata Acoustics. Nagata Acoustics will be responsible solely for the room design of the new concert hall, with the local acoustician Jean-Paul Lamoureux awarded responsibility for the project's noise control and studio renovation acoustical consulting work.

Fig-2 Concert Hall Interior
The new concert hall will implement a layout that surrounds the stage with terraced seating in a vineyard configuration. The project owner, Radio France, made this fundamental decision independent of and prior to embarking on the principal architect competition, and each of the proposal submissions adhered to the client's instructions to design a vineyard configuration. The winning submission, shown here, will serve as the basis for the concert hall's actual design.

The new concert hall will be home to Radio France's two orchestras and its mixed voice choir. The orchestras are the Orchestre National de France (Kurt Masur, Music Director) and Orchestre Philharmonique de Radio France (Myung-Whun Chung, Music Director), and the choir is Le Choeur de Radio France. A key aspect of the design process will be establishing and fostering strong and attentive communications about the design with each of these stakeholder organizations.

We began the project's acoustical design activities last June and are now in the phase of design development. Upcoming deliverables include building and testing the design in a 1/10 scale model. Construction ground-breaking is scheduled for 2007, and the planned completion date and concert hall opening will be in 2010.

Photographs: courtesy of Architecture-Studio

Salon Tessera

by Dr. Minoru Nagata,
Nagata Acoustics Founder & Executive Advisor

Salon Tessera is an 80-seat, small concert hall located in the upscale environs of Tokyu Linefs Sangen-jaya station. The building's owner, Mr. Keiichiro Kajikawa, was born and raised in this section of Tokyo. After watching the neighborhood's skyline change from traditional tile-roofed houses and low-rise modern architecture to hi-rise skyscrapers epitomized by the 27-story Carrot Tower building completed in 1995, Mr. Kajikawa decided to use his property to build a five-story, multipurpose building. K&K Building's first floor has a Seven-Eleven market and the coffee shop "Kyara," the second floor has a Denny's family restaurant, the third floor houses the Kajikawa residence, and Salon Tessera occupies the top fourth and fifth floors.

<< Project Motivation and Overview >>

Mr. Kajikawa's wife and daughter are both piano teachers. The K&K Building construction project gave them the opportunity to realize their dream for a music room focused on piano performances and audience appreciation of piano music. Mr. Shinya Suzuki of Nikken Space Design created the architectural design of K&K Building and Daiwa Housing Industry Co., Ltd. served as the general contractor. Construction began in January 2004 and completed in December of the same year.

Salon Tessera measures 13.5 m. (44 ft) deep, 5.6 m. (18 ft) wide and 6.0 m.(20 ft) high, with a rectangular footprint of 76 sq. m. (818 sq. ft). At the fifth floor level of the corners of the rear wall, a 17 sq. m. (183 sq. ft) dressing room protrudes into the hall's space, creating small areas of ceiling overhang, as shown in Fig-2. The exterior walls are built with 20 cm. (8 in.)-thick concrete. The thick concrete material makes these walls able to serve as sound-isolating walls, and the exposed concrete surfaces provide sound-reflecting surfaces within the hall.

Fig-1 Salon Tessera (Front)
Fig-2 Salon Tessera (Rear)

<< Setting the Project's Room Acoustical Design Goals >>

Deciding the appropriate acoustical characteristics for small spaces such as Salon Tessera presents the most problematic aspect of this kind of project. In Nagata Acoustics News & Opinions articles, we frequently discuss acoustical design decisions for large concert halls intended for orchestral performances. For large hall projects, the acoustician can reference well-established fundamental approaches accepted across our discipline. Acousticians have amassed data about the world's major concert halls based on experts' first-hand listening evaluations, and this information enables us to sketch, albeit in broad brushstrokes, the acoustical characteristics and qualities we should set as our goals.

However, when the project is a music room for a private residence, variety abounds regarding the instruments that will be played in the room, the scale and scope of the performances that will be staged, and whether the room will be used as an individual's private practice room, for lessons, for ensembles of friends or for family concerts. Moreover, the client owners of residential music rooms bring a great diversity of intensely personal musical approaches and preferences to these projects. Fortunately for the Salon Tessera project, the Kajikawa family clearly articulated that the hall would be used specifically for piano music and defined the primary activities for which the hall will be used.

<< Salon Tessera's Room Acoustics >>

Within the category of residential music rooms, Salon Tessera's 6 m. (20 ft)-high ceiling and 391 cu. m. (13,808 cu. ft) volume makes it a large-scale space. These dimensions tempted me to design room acoustics with lively reverberation. However, given that the hall will be used regularly for piano practice and lessons, I instead designed the hall to have relatively quiet reverberation. Other design factors I considered in connection with the hall's reverberation included preventing booming sound due to the small space surrounded by concrete walls while, conversely, controlling the drywall's absorption of low frequency sound. In addition, I achieved balanced reverberation within the space by paying attention to each of the disparate depth, width and height dimensions and effectively locating and determining the appropriate footage of sound absorbing surfaces.

Specifically, the design uses a dispersed pattern of sound-absorbing glass wool along the hall's walls and sound-reflecting, layered drywall combined with partial, distributed placement of mineral fiber dressed acoustical board at the ceiling. The design also includes strategically placed treatments for low frequency sound absorption. I recommended cloth-upholstered chairs for the hall's seating.

When the hall is arranged with 50 upholstered chairs, and the hall is unoccupied, Salon Tessera has the following reverberation times: at 63 Hz: 1.0 second; at 125 Hz: 0.8 seconds; at 250-1000 Hz: 0.6 seconds; and, at 2000-4000 Hz: 0.7 seconds.

<< HVAC System Considerations >>

One common problem I often encounter in residential music rooms, especially when they are used for family concerts, is insufficient ventilation. In rooms built to provide sound isolation, good ventilation is an essential functionality, yet its importance is generally not well understood. Significantly, the most recent residential HVAC system models perform much more quietly than earlier models. The credit for these improvements lies with the manufacturers who successfully exerted efforts to achieve quietness ratings below NC-30 (on the units' low settings) and who are now marketing the more quiet systems to the general public. Another development likely to mitigate HVAC noise in residential music rooms is the proliferation of underfloor heating systems. Implementation of an underfloor heating system eliminates all worry about noise produced during the heating of a room.

While underfloor heating has the advantage of being quiet, Salon Tessera's owner declined to use this technology because it adds to the dryness of the air during the winter season and parched air is an undesirable environment for musical instruments. Given the HVAC functionalities required, the hall's acoustical performance goals and Salon Tessera's interior architectural design concept, installation of a ducted system became the project's sole HVAC option. We worked closely with Daiwa House's mechanical and equipment engineers to fit both the ventilation ducts and sound absorption ductwork into the available space.

Detailing and implementing a ducted HVAC system proved to be one of the most challenging and painstaking deliverables of the Salon Tessera project. Ultimately, the design located ventilation openings in the room's ceiling and the projected vertical wall of the dressing room overhang. Architect Suzuki expended considerable effort to determine the exact placement and dimensions of the ventilation openings, demonstrating a tenacious resistance to compromising the integrity of his design for the hall's interior. Mr. Suzuki also resisted including installation of two ceiling fans recommended as part of the HVAC design, but the Mr. Kajikawa eventually made the decision to have one ceiling fan installed.

Soon after the hall's opening, we measured the noise level in the hall when the HVAC system was in operation and obtained NC levels between 30 and 35, which is surely not a satisfactory noise level for a classical music concert hall. As the mitigation strategy, the hall switches the HVAC system to its low setting or turns the system off during performances.

<< Salon Tessera's Pianos >>

Mr. Kajikawa equipped Salon Tessera with two pianos, one Steinway Concert Grand Piano Model C-227 and one Yamaha C5 Grand Piano. While I have much previous experience designing acoustics for residential music rooms of diverse shapes and sizes, Salon Tessera's 6 m. (20 ft)-high ceiling, its holistic and well-balanced integration of the architectural and interior hall designs, its use of a ducted HVAC system and its installation of two concert grand pianos, all reflect an exceptionally high standard of planning and implementation for a concert hall of this small scale. The project owner, Mr. Kajikawa, and his passion and decision for this project deserve the entire credit for motivating the project participants to realize this achievement.

Mrs. Kajikawa and the Kajikawas' daughter will use Salon Tessera as their practice hall and for piano instruction of their students. In addition, the hall can be rented for recitals and ensemble performances. Mr. Kajikawa especially hopes that young musicians will find Salon Tessera an attractive venue for their performances.

Salon Tessera is located at 4-22-6-4F Taishido, Setagaya-ku, Tokyo. The hall's website URL is http://www.salon-tessera.com.

Photographs: courtesy of Mr. Keiichiro Kajikawa.

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Nagata Acoustics News 06-03 (No.219)
Issued : March 25, 2006

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