Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 09-04 (No.256)

Issued : April 25, 2009

[ Japanese Version ]

Ofunato Municipal Cultural Center, "Rias Hall," Opens in Northeastern Japan

by Ayako Hakozaki

The northeastern coastline of Japan's Honshu Island is a seascape of grottoes and craggy rock formations carved into the land by the incessant beating of the Pacific Ocean's waves. As the waves beat against the rocks they generate a powerful, low-pitched sound with a rhythmic beat. The section of this coastline that stretches from southeastern Aomori Prefecture down to Miyagi Prefecture's Oshika Peninsula is named Sanriku Kaigan. Geologically, it is a ria coast landform where visitors are humbled by the stark beauty of the rough hewn coastline created by nature's unbridled power.

The new facility featured in this article, Ofunato Municipal Cultural Center, is located on the Sanriku Kaigan coastline, in Iwate Prefecture's Ofunato City. Ofunato became known throughout Japan last summer when it had the distinction of being the first northeastern Japanese city to host Japan's sixth annual Sea Festival, which included a visit by members of Japan's Imperial Family.

<< Overview and Location of Ofunato Municipal Cultural Center >>

Ofunato Municipal Cultural Center,
Ofunato Municipal Cultural Center, "Rias Hall"

In mid-November 2008, the city of Ofunato celebrated the opening of its new municipal cultural center and municipal library, "Rias Hall." The center features a large multipurpose hall, a "Multi-Space"(a flat-floored event space), a library, exhibition gallery, a performing arts studio, practice rooms and other support facilities appropriate to a multiuse facility.

While many if not most international visitors to Japan ride the Tokaido Shinkansen(the bullet train line) that travels east-west between Tokyo and Kyoto, fewer travelers from overseas experience the north-south Tohoku Shinkansen. The Tohoku Shinkansen provides access to Ofunato and Rias Hall. From Tokyo, the visitor to Ofunato takes the Tohoku Shinkansen to Ichinoseki Station (a two-hour, 10-minute ride), then the slower Ofunato train line for another two hours, to arrive at Sakari Station, which is a brief 10-minute walk from the cultural center. Alternatively, the hall can be reached by taking the Tohoku Shinkansen to Mizusawa-esashi Station (a three hours ride), then driving east on National Route 397 to Ofunato. In good weather, the drive takes a little more than one hour. Either way, traveling to Ofunato requires the patience and stamina for long train rides or hours in both a train and a car. In the spring and autumn, the satisfying natural scenery treats the eyes to rich green foliage or autumn splendor, making the journey a pleasurable one.

<< Project Participants with the Know-how for a Popular Regional Facility >>

The firm of Chiaki Arai Urban & Architectural Design served as the cultural center's architect and a joint venture of Toda Corporation and the local Takumi Construction Company collaborated on the center's construction. Architect Chiaki Arai previously designed three other cultural centers, Colare Kurobe Cultural Center (Toyama Prefecture), Kawamoto Yuyu Furusato Cultural Center (Shimane Prefecture) and Kunisaki Cultural Center (Oita Prefecture).

Mr. Arai provided the Ofunato project's concept of combining the cultural center and the city's library in a single structure, rather than building the library as a separate building. This somewhat unconventional approach to a municipal cultural center project parallels Mr. Arai's approach in his earlier three projects. At the outset of the project, Mr. Arai said, "If we only think about replacing the existing library, it would make sense to build a standalone rectangular structure. But if we understand how the facility will be used and we consider the size of the community, a combined structure offers greater convenience to the users and creates a public facility that will have a higher utilization rate and a more vibrant and enjoyable atmosphere."

As of February 1, 2009, the center already counted more than 50,000 visitors to the facility. The city of Ofunato has a population of just 42,000 people and, in February, the hall had been open less than three months, so from the reported utilization of the center, we get a sense of the community's exuberant outpouring of interest and desire for this long-awaited local facility. Also, the multiple visits to the center by the local residents validate the appropriateness of Mr. Arai's combined library and cultural center design approach.

<< The Large Hall >>

Stage view of the Large Hall
Stage view of the Large Hall

Large Hall audience seating area
Large Hall audience seating area

Design elements throughout Rias Hall use colors, patterns and textures that reflect the natural imagery of the Sanriku Kaigan coastline and the inspiration of its craggy seascape. The 1,100-seat Large Hall's interior, in particular, draws its design inspiration from Sanriku Kaigan's rocky shoreline and the abundant waves that beat against it.

The hall's sound reflection panels create a smooth transition from the stage's proscenium opening. The white ceiling reflection panels, designed in the image of the white clouds above the Sanriku Kaigan shoreline, hang above the audience seating area as if floating gently away from the stage. We divided the ceiling sound reflection panels into sections and set each section at the optimal angle to direct rich sound reflections to the stage and the audience seating areas.

The sidewalls of the audience seating areas and the low walls topped by banisters that surround the blocks of balcony seating are all exposed concrete surfaces. We chose the concrete material because of its excellent ability to reflect low frequency sounds. We softened the strength of the concrete's sound-reflecting property by applying a Japanese finishing treatment called "kotataki" that adds a slightly pebbled texture to the concrete surfaces.

The hall's balcony blocks vary in size and take their inspiration both from the rocky shoreline seascape and the idea of a flotilla of ships one might see from the coast. The three-dimensional design and placement of the balcony blocks provide excellent sight lines for the audience as well as a feeling of proximity to the stage.

Large Hall audience seats
Large Hall audience seats

In addition to the above design elements that focus on the hall's use for music performances, we installed electrically operated sound absorption curtains along the sidewalls that can be extended or retracted during speaking events to reduce the hall's reverberation characteristics and increase the clarity of speech. For smart imagery , the front sides of the curtains are covered with the acoustically transparent horizontal louvers. Also, to complete the seascape imagery, the tops of the audience seatbacks form visually curved lines and the seats are upholstered in an assortment of eight hues of blue, ranging from dark to light, giving the audience seating the appearance of rippling waves.

<< Ofunato Municipal Cultural Center Sound Isolation Design >>

Multipurpose facilities house rooms intended for a variety of purposes under a single roof, and the need for sound isolation design inevitably occupies a prominent place among these projects' priorities. This project was no exception and, in order to maximize the simultaneous use of as many of the center's rooms as possible, we focused considerable attention on the center's sound isolation design.

Floor plan of the cultural center
Floor plan of the cultural center

For the starting point of our sound isolation design, we established one layout zone for the Large Hall and another zone for the library and other facilities, which include the Multi-Space, the studio and other creative activity spaces. Between the zones, we specified that expansion joints be used in the structural design in order to prevent the propagation of sound through the building's solid structural elements.

As part of the center's programming, we planned for the Multi-Space to be used either as a single rectangular space or in combination with the corridors and meeting rooms adjacent to it. To implement this concept, we installed movable sound-isolating partition walls between the Multi-Space's first floor level and the corridors, and the meeting rooms. For events that will generate large sound volumes, the movable, sound-isolating partition walls will isolate the large sound volumes within the Multi-Space.

Because the creative activity rooms and the library wrap around the perimeter of the Multi-Space on the second and third floors, putting them in close proximity to the Multi-Space, we installed walls with rated anti-vibration and sound isolating properties for t the Multi-Space's second and third floor sidewalls. Also, we implemented anti-vibration and sound isolating structural designs for the studio and each of the practice rooms. As a result of all of these measures, we achieved a high degree of sound isolation between each of the rooms and also between the Multi-Space and the library.

<< Expect to be Impressed by Rias Hall's Architecture and Interior >>

Restaurant sidewalls
Restaurant sidewalls

Studio wall section
Studio wall section

By inserting a sampling of photos from the cultural center into this article, I aim to give the reader a sense of its many intriguing and creative structural and interior design elements. When a visitor sets foot in this building and feels its powerful presence, thoughts immediately also turn towards the people who made the building possible-the architect's impeccable attention to detail and the untiring commitment, enthusiasm and skill of the contractors and construction crews.

Coming the season of fresh green leaves, I highly recommend a trip to Ofunato to experience both a performance and the new cultural center's architecture. In addition to delightful arts and architecture, delicious seafood fare also awaits you when you visit Ofunato City and its Rias Hall.

Ofunato Municipal Cultural Center, "Rias Hall"

Sanctuary Acoustics at Japan Evangelical Lutheran Church Miyazaki

by Dr. Minoru Nagata, Founder of Nagata Acoustics

Japan Evangelical Lutheran Church Miyazaki (located in Miyazaki Prefecture in eastern Kyushu Island) built a new sanctuary on land adjacent to the church's old sanctuary building and, after 10 months of construction, held a dedication ceremony for the new sanctuary on June 7, 2008. All worship activities moved to the new sanctuary at this time. However, the new sanctuary project included adding three pedal stops and another bellow to the pipe organ and this work, plus relocation of the pipe organ to the new sanctuary and on-site voicing, required additional time to complete. On February 15, 2009, the church held a pipe organ dedication ceremony, marking the completion of this church project.

<< The Motivation and Acoustical Principles for the New Sanctuary Project >>

Even though the Bernhardt Edskes pipe organ that is installed in the new sanctuary now has 13 pedal stops, it looks a pretty small instrument in the balcony space. Nevertheless, the elegance of its tone and the satisfying fullness of its low frequency sounds captivate the listener. Congregants of this church had experienced pipe organ music in the acoustics of Europe's historical cathedrals and, after installing the pipe organ in the old sanctuary in 1998, it was a natural progression that these congregants would desire an acoustically appropriate worship space for their Bernhardt Edskes pipe organ.

According to the expectations of the congregation, we defined the following five acoustical design rules for the new sanctuary project.

  • (1) Maximize the ceiling height of the new space.
  • (2) Construct the ceiling and walls of concrete.
  • (3) Locate the pipe organ in a newly constructed organ balcony.
  • (4) Use sound absorption methods to fine tune the frequency characteristics of the sound reverberation time.
  • (5) Support the objective of clarity of speech during sermons by installing a sound amplification system.

<< The New Sanctuary Project Implementation and Measurements >>

Yoh Architects & Associates created the architectural design for the new sanctuary. Shida Gumi Corporation served as the project's general contractor.

 Fig. 1: New sanctuary plan drawing
Fig. 1: New sanctuary plan drawing
Fig. 2: New sanctuary cross-section drawing
Fig. 2: New sanctuary cross-section drawing

Fig. 4: Pipe organ balcony
Fig. 4: Pipe organ balcony

Fig. 3: Pulpit (temporary setup)
Fig. 3: Pulpit (temporary setup)

Figs 1 and 2 show the new sanctuary's plan and cross-sectional drawings. Figs 3 and 4 are photos of the wall of the new sanctuary that has the pulpit and organ balcony. It is well worth noting that, compared with the sanctuary's overall spatial volume of 1000 cu. m. (35,315 cu. ft) and its maximum ceiling height of 9 m. (29.5 ft), the pipe organ is a modest presence, as the photos clearly show.

Fig. 5 shows the reverberation characteristics of the new sanctuary before and after the installation of the pipe organ. The presence of the pipe organ created only a minimal reduction in the new sanctuary's reverberation characteristics. The same Fig. 5 also shows the calculated estimated reverberation characteristics of the new sanctuary when it is fully occupied with 80 congregants.

For reference purposes, Fig. 6 compares the reverberation characteristics of the wood-panel-construction old sanctuary (unoccupied and without pews) and the new sanctuary (also under unoccupied conditions). To achieve acoustics that come close to having the rich low frequencies of Europe's historical cathedrals, wood-panel construction is not an option and the chart of Fig. 6 provides useful data in this regard.

 Fig. 5: New sanctuary reverberation characteristics (before and after pipe-organ installation)
Fig. 5: New sanctuary reverberation characteristics
(before and after pipe-organ installation)
Fig. 6: Comparison of the new and old sanctuaries reverberation characteristics
Fig. 6: Comparison of the new and old sanctuaries
reverberation characteristics

I will be pleased if this article about the tones and acoustics of the new sanctuary in Miyazaki provides useful information to readers with an interest in pipe organs and contributes to the ongoing understanding of church architecture.

Israel's Frederic R. Mann Auditorium Renovation Project

by Yasuhisa Toyota

Nagata Acoustics has been named as the acoustical consultant for the renovation of Frederic R. Mann Auditorium in Tel Aviv, Israel. The current Mann Auditorium dates back to the 1950s. Its planning and construction began in 1951, shortly after the 1948 founding of the State of Israel, and it opened in 1957.

<< Overview of the Auditorium and the Need for Acoustical Renovations >>

Mann Auditorium (Interior View)
Mann Auditorium (Interior View)

At the time, the hall's design focused on the auditorium as the home base of the Israel Philharmonic Orchestra and prioritized providing space for the orchestra's performances and rehearsals. However, on days when the orchestra is not using the hall, it has come to be used as a multipurpose venue for popular music concerts, symposia, dance performances, and so on.

The auditorium is a large hall that seats 2,715, with a configuration that is basically a fan shape and a rather low average ceiling height of 12 ~ 13 m. (39 ~ 43 ft). For many years, the orchestra has expressed discontent with the auditorium's acoustics and, in the past, a number of plans were formulated to renovate the auditorium's acoustics, but they did not come to fruition. The basic shape of the auditorium and its low ceiling height are the major sources of the auditorium's acoustical problems.

<< Historic Preservation Groups' Previous Objections to the Project >>

Room Shape (Existing and Proposed Changes)
Room Shape (Existing and Proposed Changes)

In 2001, a comprehensive plan was formulated to renovate the entire auditorium. Several times thereafter, renovation plans that included acoustical renovations progressed to more concrete discussions and review only to be thwarted by the objections of historical preservation groups.

In 2003, UNESCO proclaimed the Bauhaus architecture of the area of Tel Aviv known as "White City" a World Heritage Site. Mann Auditorium, with its Bauhaus architecture and location in "White City" was not exempted from the preservation constraints. The acoustical need to increase the auditorium's spatial volume was to be solved by raising the roof height of the overall structure, but this design change of the renovation plans failed to obtain approval.

<< The Plan to Renovate the Auditorium and Keep the Bauhaus Exterior >>

For this project, we began our work by studying how to achieve the acoustical renovation objectives through changes to only the interior of the auditorium while keeping the auditorium exterior unchanged. Keeping the exterior unchanged would mean that the roof remains at its current height. Based on our study, we determined that the project can achieve its desired outcomes and the decision was made to move forward with the project.

Some of the renovation design specifics include: raising the interior ceiling height to 15 ~ 16 m. (49 ~ 52 ft) (as shown in the accompanying longitudinal section drawing); creating low partition walls that separates the central front portion of the first floor audience seating from other seating on this level in order to obtain sound reflections from the partitions' surfaces; and changing the angles of the auditorium's sidewalls, also in order to ensure that effective sound reflections reach the audience seating. These and other renovation details will be incorporated into the design development and construction phases that are now moving forward. I look forward to sharing highlights of these project phases in a future article after the completion of the project.

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 307A
Los Angeles, CA 90025, U.S.A.
Tel: +1-310-231-7818, 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 ]