Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS


News 10-09 (No.273)

Issued : September 25, 2010

[ Japanese Version ]

Shimonoseki City's "Dream Ship" Multipurpose Complex Opens

by Fumiaki Sakamaki

Dream Ship's exterior
Dream Ship's exterior

Dream Ship's floor plan 1st floor, 2nd floor
Dream Ship's floor plan
1st floor, 2nd floor

Dream Ship's floor plan Section of the large hall
Section of the large hall



At the westernmost tip of Japan's Honshu Island (the largest of Japan's four main islands), in Yamaguchi Prefecture's Shimonoseki City, the multipurpose complex "Dream Ship" opened in March, 2010.

With a design inspired by the shape of passenger ships that travel the Kanmon Kaikyo ("Kanmon Straits"), Dream Ship houses Shimonoseki's Lifelong Learning Plaza and the Shimonoseki City Central Library. The planners of this multipurpose complex hope it will become Shimonoseki City's key destination and venue for city residents participating in and attending cultural and performing arts activities and events.

<< Overview of the Dream Ship Project >>

In addition to the standard facilities of a central library, Dream Ship houses the new Lifelong Learning Plaza. The highlights of the plaza's facilities are its large and small halls. In addition to the halls, the plaza has two rooms for performance rehearsals and practice and two other rooms dedicated to music, as well as classrooms, a craft workshop and a tatami mat room for traditional Japanese cultural activities.

The Dream Ship project used Japan's Private Finance Initiative (PFI) for its financing. Japan's PFI promotes the use of private financing to fund public infrastructure projects and enables operational and maintenance responsibilities for completed projects to be entrusted to private organizations.

The architectural firms of Daiken Sekkei and Pelli Clarke Pelli Architects Japan worked together as a team to design the Dream Ship project. Magara Construction served as the general contractor.

<<Sound Isolation Design >>

Dream Ship's layout maximizes the building's limited space to fit many rooms intended for a variety of different purposes into the first through third floors of the Lifelong Learning Center. Given these conditions, our sound isolation design included evaluating the locations of the various rooms in relationship to each other, and how and when they will be used, as well as the costs involved to ensure efficient use of the available space. Based mainly on these parameters, we determined the sound isolation objectives for Dream Ship's rooms and spaces.

Because of the proximity of the small hall and the two dedicated music rooms to the large hall, we adopted an anti-vibration and sound isolation structure for the small hall and two music rooms. Also, for the partition wall between the upper portion of the large hall and the adjacent fourth floor library, we specified the construction of a sound isolation wall that includes both a reinforced concrete wall and four layers of 21 mm (0.8 in.) thick gypsum board. Through these measures, we created strong sound isolation around the large hall.

To obtain an effective sound isolation performance level both between the large and small rehearsal rooms and between these rooms and other nearby rooms, we also adopted an anti-vibration and sound isolation structural design for the two rehearsal rooms. Because we anticipated that activities in the crafts workshop will include hammering and other impact-producing work, we specified a floating floor (on glass wool) for this room.

As a result of our sound isolation design, we achieved a sound isolation performance level of at least D-75 between Dream Ship's large and small halls. >From music room No. 1 to the large hall, we achieved a sound isolation performance level of at least D-85, and from the library to the large hall, we achieved a sound isolation performance level of D-70.

<<Room Acoustics Designs for the Large and Small Halls >>

Umi-no Hall (
Umi-no Hall ("Hall of the Sea"), the large hall

Kaze-no Hall (
Kaze-no Hall ("Hall of the Winds"), the small hall

Officially named "Umi-no Hall" ("Hall of the Sea") the large hall has an architectural design that drew inspiration from imagery of the deep seas and the waves on their surface. The hall has a single slope and 805 seats. Acoustically, the hall is a multipurpose auditorium designed with the priority on acoustics for music performances.

The hall's room design begins with a basically rectangular, shoebox configuration footprint. As the audience section slopes toward the rear of the hall, the number of seats per row decreases, so that the width of the audience section becomes narrower, creating clear cross-sectional demarcations within the single slope audience seating. Also, because of the progressively narrower width of the audience seating as it slopes upward towards the rear of the hall, portions of the sidewalls have undersides that form ceiling surfaces over the far left and right seats of lower rows. Secondary sound reflections generate off of these ceiling surfaces and bring abundant secondary sound reflections to cross sections of the audience in the rows below. In addition, because our pre-construction computer simulations identified that these reflections would also cause undesirable sound focusing phenomena in the central part of the audience seating, we specified that the walls be built with a slight tilt outward and we proposed adding sound diffusing elements to the sidewall surfaces. We worked with the architectural team to successfully implement these acoustical design specifications and proposals, including sound diffusing wall elements of varying sizes placed with random spacing.

For this hall, we designed a sound reflection panel system for use during classical music concerts. The reflection panel system blends with the 12 m. (39 ft) high proscenium stage opening to create the sense of a unified space between the stage and audience. We also prioritized obtaining rich low frequency sounds during classical music concerts by specifying that multiple layers of board be used for the sound reflection panels, the interior walls alongside the audience seating and the hall ceiling. The use of multiple board layers ensures that these surfaces have sufficient mass to effectively reflect low frequency sounds. Finally, to add reverberation time flexibility to the hall so that the acoustics can be adjusted to suit different kinds of programs, we placed retractable sound absorbing curtains behind the sound diffusing elements of the hall's side and rear walls.

For Dream Ship's small hall, the architects took their inspiration from another image in nature, that of wind as it passes through a grove of trees, rustling the leaves. Named Kaze-no Hall ("Hall of Winds"), this hall is shaped like a box, with a flat floor. It seats an audience of 204 persons and has acoustics designed for the performance of non-amplified music. We specified sound diffusing protrusions and indentions for all of the walls of this hall, including both those around the stage and around the audience seating section, and we installed sound absorbing material (perforated board and glass wool) behind the sound diffusing wall elements.

When the large hall is configured with the stage sound reflection system set up, the reverberation time measures 2.2 seconds with the hall fully occupied and 1.8 seconds when the hall is empty (both at 500 Hz). The difference between when the sound-absorbing curtains are extended to their open position and when they are retracted is 0.1 seconds for mid-range and higher frequency sounds. The small hall's reverberation time measures 1.4 seconds with the hall fully occupied and 1.2 seconds when the hall is empty (both at 500 Hz).

<<Enjoying Dream Ship's Commemorative Inaugural Concert >>

On Sunday, March 28, 2010, residents of Shimonoseki City enjoyed the opportunity of attending Dream Ship's eagerly awaited commemorative inaugural concert. The concert program featured a recital by Japan's virtuoso pianist Hiroko Nakamura. With every seat of the large hall filled, I joined the audience in listening to Ms. Nakamura's dazzling performance.

The hall's acoustics delivered exceedingly clear tones and I was able to confirm that we achieved our acoustical design objectives for this project. The audience gave Ms. Nakamura enthusiastic applause throughout the concert and she thanked them by playing four encores.

Shimonoseki City's new combined library and lifelong learning center, Dream Ship, will surely enhance cultural and performing arts opportunities for the city's residents. I wish the facility much success and hope that the residents will enjoy Dream Ship for a very long time.

Dream Ship's home page can be found at http://www.dream-ship.co.jp/

Seiler Piano Duo's Kayabuki Ongaku-do Concerts and the Kayabuki Ongaku-do Competition

by Dr. Minoru Nagata, Founder of Nagata Acoustics








The husband and wife piano duo of Kazuko Masada Seiler and Ernst Seiler perform in the unique surroundings of their own thatched-roof structure on land nestled in the low mountain backcountry about one hour's distance, by train, from Kyoto. Their performance venue, Kayabuki Ongaku-do, is located in the farming hamlet of Goma, which can be accessed by taking the San-in Train Line from Kyoto to Goma Station, and then walking for some 15 minutes on a road that goes through bucolic farmland with views of the low rising mountains of the area.

<<The Kayabuki Ongaku-do Concert Space >>

"Kayabuki" refers to a kind of traditional Japanese thatched roof. The structure that the Seilers now use as Kayabuki Ongaku-do (literally, "Thatched Concert Hall") has this kind of roof and was originally built in Fukui Prefecture (northeast of Kyoto) as the main structure of a Zen temple compound. The Seilers became the owners of this building, dismantled it and relocated it to Goma. The reconstructed Kayabuki Ongaku-do has a flat floor, a surface measurement of 120 tatami mats (each mat being about .9 x 1.8 m.) and a 9 m.-high ceiling. The Seilers added a stage and, on the tatami-mat floor, created seating for an audience of 250 people. The audience sits on traditional zabuton floor cushions arranged on two levels around three sides of the stage. In 1989, the Seilers inaugurated their Kayabuki Ongaku-do as the main concert venue for their piano duo concerts.

For the walls of Kayabuki Ongaku-do, the Seilers retained a portion of the original paper shoji walls and glass shoji walls, and they left the ceiling open, exposing the kayabuki thatching of the roof. For the tatami mats, they installed a type of mat known as the "C style mat", which has a polystyrene foam core instead of straw. The resulting acoustical environment typifies that of traditional Japanese rooms, being devoid of any sensation of sound reverberations.

Nevertheless, because pianos have sound boards and because of how pianos resonate, Kayabuki Ongaku-do works well as a venue for the Seilers' performances. At Mr. Seiler's request, I provided a strategy to optimize the venue's acoustics. My suggestions included using thick glass for the glass shoji walls behind the stage area and suspending a curved, sound-reflecting panel in the air space above the pianos.

<<Piano Duos and Duets, and the Kayabuki Concerts >>

Before meeting the Seilers, my experience with piano duos consisted mostly of memories of students accompanying their piano teachers and students collaborating for recitals. According to Mr. Seiler, in Europe, piano duos have an enduring popularity in familial settings. At one of the Seilers' concerts, I listened to Mozart's Sonata for Two Pianos and for the first time experienced the delight of music for two pianos. I learned that many famous composers, from Beethoven, Brahms, Dvorak and Rachmaninoff to more contemporary names such as Samuel Barber, all wrote either compositions for four hands on one piano or piano duets. When the Seilers can find the time, they like to travel to the libraries of Europe in search of piano compositions written for four hands on one piano and for two-piano duets.

Of course, the twice yearly concerts they began in 1989 keep the Seilers busy. They perform at Kayabuki Ongaku-do for several days in the early summer and again every fall. I attended one of their afternoon concerts on June 6. For this concert, a Kyoto tour company arranged the transportation and completely filled the 80 seats of two buses. In the hamlet of Goma, the twice yearly Kayabuki concerts have become part of the established seasonal calendar anticipated by the local population.

Many concert halls create the feeling of being enclosed in a space away from the out-of-doors. By contrast, while I listened to the Seilers' piano duets at Kayabuki Ongaku-do, I could sense the green of the surrounding hills and the wind in the trees, giving this venue a unique charm. During the intermission, the audience enjoyed homemade rice balls and wine refreshments.

<<The Kayabuki Piano Duo Competition >>

In addition to the twice yearly concerts, the Seilers hold periodic piano duo competitions once every two years. They began the competitions in 1998 and are in the process of holding the seventh competition this year. The competition's first round completed in July and a second round will take place on October 9 and 10. Thereafter, the final competition will be held at Kayabuki Ongaku-do on November 6 and 7. Admission to the final competition is free of charge.

Contestants participating in Section A of the competition perform works for four hands on a single piano. Section B participants perform compositions for two pianos. This year's competition features the works of Schumann and Chopin. The performances will offer audiences the opportunity to enjoy this special kind of piano music in a unique setting.

For more information, visit the Seilers' website at http://www.kayabuki.com or contact them by e-mail at kayabukiongakudou@hotmail.com.

The Karuizawa Arts Festival 2010 Ohga Concert Hall Series Chopin Concert
"Dazzling Music Travels: the Music and People Chopin Loved" (Wed., August 25, 2010)

by Dr. Minoru Nagata

This past August, Karuizawa Ohga Concert Hall participated in Karuizawa Arts Festival 2010, with offerings that matched the festival's theme for this year, commemorating the two hundredth anniversary of the 1810 birth years of both Chopin and Schumann. On Monday, August 2, the hall held a day of concerts titled "Romantic Schumann", which included two, two-hour programs, one featuring the composer's chamber music and one dedicated to his choral works. The second day of concerts, on Wednesday, August 25, included a large variety of compositions arranged into five programs of one hour each, all under the title "Dazzling Classical Music Travels, the Music and People Chopin Loved."

I attended the August 25 concert, starting with the first program at 10:30 a.m. and continuing through the fifth program, which concluded at 8:30 p.m. Through this nearly full day of performances, the program transported the audience through a range of eras and, instead of limiting the program to works composed by Chopin, also included compositions that influenced Chopin's music and works by composers who were influenced by Chopin.

The day's program, from morning to night, encompassed five sessions, numbered Vol. 1 through 5. Across the five performance sessions, works by Chopin, Schumann and Liszt represented the most performed compositions. Earlier eras were represented by Rameau and J.S. Bach, and the program included the works of Rachmaninoff and Messiaen as examples of more recent, Chopin-influenced compositions. In addition to the three pianists Seizo Azuma, Yuko Hisamoto and Ichiro Nodaira, violinist Yayoi Toda, cellist Kikuchi Tomoya and soprano Akie Amou participated in this diverse mix of performance content. For me, the masterpiece of the day occurred during Vol. 2 of the performances, when Yuko Hisamoto performed on the 170 year-old Pleyel piano, the instrument that Chopin loved. Ms. Hisamoto's playing on this incredibly valuable piano, which was built in 1840, produced quiet tones of the most exquisite beauty.

The Japanese Emperor and Empress attended the Vol. 2 performance, which played to a full house. During the other performances, Ohga Hall was about 50% full and the hall's acoustics produced rich reverberations.

Unfortunately, on the day of the performances, Karuizawa's weather was uncharacteristically hot, and the hall did not have sufficient lobby seating for the many audience patrons who waited at the hall during the hour long intermissions between performances, resulting in a situation of particular discomfort to the seniors among the audience. In the future, I suggest that the planners of this kind of "marathon" performance schedule plan ahead to ensure the comfort of patrons during the long intermissions.


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 ]