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

Nagata Acoustics News 04-09 (No.201)
Issued : September 25, 2004

"MUZA" Kawasaki Symphony Hall Opens

by Akira Ono

On July 1, 2004, MUZA Kawasaki Symphony Hall opened with a gala inauguration concert by its resident orchestra, the Tokyo Symphony Orchestra, under the baton of its long-time conductor, Maestro Kazuyoshi Akiyama. The program featured Mahler's Eighth Symphony, "The Symphony of a Thousand."

True to its name, "The Symphony of a Thousand" is a powerfully dramatic composition that rises to a memorable climax at its conclusion, making it seem an appropriate choice for an inauguration. However, because this work requires a large chorus, this program selection necessarily created a difficult challenge for the conductor and performers who were still new to the hall, demanding that they achieve unity of breath and timing in the still unfamiliar venue. A lack of coordination would have been sufficient cause for unfavorable reviews. Nevertheless, at MUZA Kawasaki Symphony Hall's opening gala, the performers met the challenge superbly and to strong laudatory acclaim. The successful opening left all involved with a happy sense of relief and accomplishment.

<< Planning the Hall as Part of a Larger Complex >>

MUZA Kawasaki Symphony Hall is part of a new complex planned as the Kawasaki Station West Redevelopment Project on land at the western exit of the Japan Railroad's (JR) Kawasaki Station. The public planning commission, which began under the name "Toshi Kiban Seibi Kodan" (Urban Development Corporation) and is now named "Toshi Saisei Kiko" (Urban Renaissance Agency), retained MHS Planners, Architects & Engineers as the architect for the overall project and ACT Planning for the concert hall's design.

The redevelopment project included a 27-story office tower and a separate concert hall building connected by a multi-story, glass-enclosed shopping Galleria. A pedestrian deck facilitates access between JR Kawasaki station and the new buildings.

Based on the expected flow of foot traffic to-and-from the train station and through the buildings, and because of other overall project constraints, the project plans located the concert hall building on the train station side of the site. At their closest point, the concert hall building is only 30 m. (33 yards) from the railroad tracks, a distance that makes the building very susceptible to vibration from passing trains.

MUZA Kawasaki Symphony Hall
Stage view (left) and Audience view (right)

Section of the hall

<< The Hall's Anti-noise and Anti-vibration Needs >>

Our anti-vibration strategy for the concert hall building began with the construction technique of adhering rubber panels to the underground frame of the building and included other major structural anti-vibration measures. In addition to the vibration from passing trains, the basement floors of the concert hall include a garage with sliding machinery for stacking parked cars, creating another source of noise and vibration. Isolating the concert hall from this noise and vibration was another key aim of our acoustical design. During our post-construction evaluations, we confirmed that the vibrations and noise from passing trains and the operation of the parking machinery cannot be detected at all by human beings in the concert hall.

<< Concert Hall Room Acoustical Design >>

The concert hall's room design is based on staggered blocks of seating placed around the stage in a vineyard configuration. The distinctive feature of the configuration's design is that the staggered blocks of seating rise in a spiral pattern, so that the horizontal plan of the hall is asymmetrical.

We installed large, sound-reflecting acoustical panels above the front portion of the stage and extending out over some of the first floor audience seating. The height of these overhead panels can be controlled electrically to adjust the hall's acoustics. Additionally, the electrical controls enable adjustments to the angle of a portion of the panels.

The spiral shape of the concert hall's walls, the overhead acoustical panels and sound-reflecting surfaces at the ceiling that we shaped to form an envelop around the acoustical panels, together evenly balance the sound reflections and the timing in which the sound reflections reach both the audience and the stage. We achieve the balance in both quantity and timing of the sound reflections through precise control of the shapes and angles of all of the hall's sound-reflecting surface elements.

In addition, we made the hall user-friendly for events other than acoustical musical performances (specifically, events that use sound amplification and require excellent speech intelligibility) by installing acoustical curtains at the rear of the stage. The acoustical curtains are operated electrically.

<< The Resident Orchestra's Role During Hall Design and Construction >>

Initially, plans for MUZA Kawasaki called for a multipurpose hall. As more detailed planning progressed, the client entered into discussions with the Yomiuri Nippon Symphony Orchestra with the aim of that orchestra becoming the new hall's resident orchestra. The decision to implement a vineyard configuration concert hall came from the client's expectation that a major Japanese orchestra would enter into a resident-orchestra franchise agreement with the new hall.

However, for reasons that need not concern us here, during the hall's construction phase, the Yomiuri Nippon Symphony Orchestra removed itself from the project and from the franchise discussions. Thereafter, the client (Kawasaki City and the public redevelopment corporation) gave serious consideration to how the vineyard configuration hall could be made usable as a multipurpose hall. The reevaluations of the design included not only the hall's vineyard configuration, but also many elements of the stage details and room acoustical designs that we had incorporated to meet specifications provided by the Yomiuri Nippon Symphony Orchestra. The project proceeded to reconsider and re-work numerous hall requirements.

One of the hall's requirements raised for reconsideration was the modular stage-floor riser mechanism. The client questioned if the riser mechanism should be removed from the scope of the project, since there are many halls that do not have this feature. In order to make a decision, Kawasaki City decided to hold hearings at which it solicited the recommendation of Tokyo's orchestras. (Tokyo is home to more than 10 professional orchestras.) As a result of some discussions and conversations during the hearings, Kawasaki City was able to negotiate a resident-orchestra contract with a different orchestra, the Tokyo Symphony Orchestra.

From our perspective as the project's acoustical consultant, we received the news of the franchise contract with the Tokyo Symphony Orchestra with welcome ears, and we immediately made every effort to adapt our design and specifications to the requests of the Tokyo Symphony Orchestra. The resident orchestra's office, practice room, locker rooms and instrument storage room had already been removed from the building plans. We added them back into the project. We made changes to the modular stage-floor riser mechanism to meet the specific requirements of the Tokyo Symphony Orchestra's players. In our opinion, the adaptation and implementation of the stage-floor riser-mechanism will have a significant influence on the Tokyo Symphony Orchestra's creation of its own unique sound in its new home hall.

<< The Resident Orchestra's Role during Hall Tuning >>

Regardless of the unexpected turn of events leading up to a resident orchestra's association with a hall, a resident orchestra's presence makes a significant impact on a hall. The meaning of having a resident orchestra associated with a hall goes far beyond an orchestra's scheduling a series of regular subscription concerts there.

In the case of MUZA Kawasaki Symphony Hall, as soon as the hall's construction was complete, the orchestra began practicing in the hall. With each practice session, the orchestra rotated its conductors and played different works from its repertoire. One could hear the musicians becoming accustomed to the hall and the change in the sound and impression the orchestra produced. One could hear the orchestra's confidence grow as it became convinced that the hall would not disappoint the audience.

After the installation of the hall's Swiss-made Kuhn organ, we adjusted the height and angle of the overhead acoustical panels while listening to comments and opinions from the orchestra's players. At first, the players said they could not hear the other instruments, but with the fine-tuning of the acoustical panels, the ability of the musicians to hear themselves improved dramatically. The musicians' positive attitude as we worked with them to achieve the desired result was evidence of the trust they developed for the hall's ability to provide fine acoustics.

The orchestra is still perfecting its use of the stage-floor risers and will require more experience performing in the hall to achieve the best set-up for each composition and each program. The Tokyo Symphony Orchestra's new musical director, Maestro Hubert Soudant eagerly tests different riser heights when he prepares the orchestra for new compositions and we are certain that his experimentation will be well rewarded as he finds precisely the height he wants for each program.

<< MUZA Kawasaki's Early Successes >>

Since MUZA Kawasaki's gala opening concert, the hall's classical music concerts have performed to sell-out and near sell-out audiences. We hear that the hall's subscription concert series is also selling well. Some commentators in Japan asked why a municipal government was spending money on a large-scale concert hall at this point in time. Kawasaki City has a goal to be a City of Music. The new concert hall, with its resident orchestra securely at the helm, surely seems poised to move Kawasaki City towards its self-proclaimed goal. It sounds like this could well be the right answer to the question of why the city funded the MUZA Kawasaki project.

The MUZA Kawasaki website address is http://www.kawasaki-sym-hall.jp/index_e.shtml/.

MUZA Kawasaki Symphony Hall's Sound System

by Motoo Komoda

The primary purposes of the MUZA Kawasaki Symphony Hall sound system are to provide an in-house paging and public address (PA) capability and to amplify speech intelligibly for lectures and ceremonial events. For events that may require other loudspeaker equipment, we made the assumption that the events' organizers will either use the hall's portable loudspeakers or bring their own additional equipment.

<< Types of Loudspeakers >>

MUZA Kawasaki Symphony Hall has a system of multiple individual loudspeaker units distributed across the hall ceiling and a suspended loudspeaker cluster. In addition to these loudspeakers, the concert hall has fixed loudspeakers at the sides of the stage, at the front of the stage, and hung from the undersides of the balconies. These support loudspeakers either provide additional sound amplification to specific sections of audience seating or feedback monitoring to the person speaking on stage. Which support loudspeakers are appropriate to use in a given situation should be determined on a case-by-case basis depending on how the acoustical curtains are deployed, whether all the audience blocks are occupied and the configuration of the microphones being used.

<< PA Loudspeaker Use for Classical Concerts >>

Placement and Direction of
Ceiling Loudspeakers
For the typical classical music concert, paging and other PA announcements will rely on the 33 loudspeakers embedded in the ceiling. The accompanying drawing depicts the placement of these loudspeakers and the direction of the sound each loudspeaker generates.

The embedded ceiling loudspeakers are installed above the ceiling so that they are not visible to the audience. The openings for these loudspeakers are covered with a net-like fabric that helps to disguise them from view.

After the completion of the hall's construction and since the hall's opening, I have had several opportunities to check the performance of these loudspeakers when used for PA announcements and speeches from the stage. In this auditorium, with acoustics characterized by a long reverberation time, the loudspeakers provide ample clarity and performance for their intended purposes.

<< Large Loudspeakers for Lectures >>

Canopy, Loudspeakers and Curtains
We installed a total of 10 large, hanging loudspeakers in the hall for use during lecture programs, 5 on each side of the auditorium. These loudspeakers are visible to the audience when they are in use. When they are not in use, they can be raised above the "canopy" of large ceiling reflection panels so that they are out of sight. In the accompanying photograph, the loudspeakers are shown in their lowered position. The white bands seen behind the loudspeakers are acoustical curtains set along the stage rear, and the small black fixtures hanging from batons are additional stage lights. I have confirmed through listening experiments that these large loudspeakers provide effective and clear amplification in the hall, without any sense of compromise. The deployment of the acoustical curtains plays an important role in abating the hall's reverberation for this configuration.

<< Other Sound System Equipment >>

Here is a survey of the hall's other sound system equipment. The hall has a digital sound mixer, which is connected via an optical transmission line to a console at the left stage wing. The hall is also equipped with a portable, analog mixer for use during recording sessions.

The most anticipated use of recording microphones is for the recording of orchestral performances. For this purpose, we equipped the hall with a hanging, six-channel, three-point microphone and with six single-point hanging microphones disbursed in six locations. All of these microphones are suspended directly from the ceiling.

For TV broadcast capability, we anticipated that the TV station's broadcast vehicle will be parked in the garage below the hall, and we ran optical fiber for the camera, coaxial cable and sound transmission lines from the garage to the sides of the stage and then to the locations in the audience seating where the TV camera will likely be situated. The hall is ready for transmission and receipt of both video and sound signals.

The hall is also equipped with intercoms, closed circuit TV monitors and dressing room occupancy indicator lights. These items have both wired components and wireless handsets that provide full and flexible communication capability between the back-stage areas and other parts of the auditorium building during performances and rehearsals.

Acoustical Design of Ceremore Concert Hall Musashino

by Dr. Minoru Nagata

The hall discussed in this article is a small, 90-seat concert hall located on part of the second story of a new office building built by Ceremore Tsukuba Company as its company headquarters. Ceremore Tsukuba is a rapidly growing enterprise with many branch locations in Tokyo and the surrounding area.

The company's core business is funeral preparations, Buddhist memorial altars (Butsudan) and related items. In recent years, due to the entrepreneurial foresight of the company president, Mr. Masashi Tsuji, the company has successfully expanded its operations to include the lease and sale of home nursing equipment such as wheelchairs, adjustable beds and related convalescent and long-term care products. Additionally, the company takes an active role in community philanthropy.

The new concert hall is one example of how the company gives back to the local community. The story of this hall's realization, and Nagata Acoustics participation in the project, begins with the hall's Bösendorfer model 225 "Strauss" half-concert-grand piano, a wonderful instrument that is a rarity in Japan and a treat for piano music lovers to experience.

<< A Concert Piano Tuner's Concern that the Hall Suit the Piano >>

My introduction to the Ceremore Concert Hall Musashino project began last November 2003, when I received a telephone call from Mr. Zengo Sano, a master piano tuner who has introduced this piano.

The room was a simple conference room in an ordinary office building, with a typical low ceiling and glass windows on two sides. Mr. Sano said he was worried about the appropriateness of the space for as special an instrument as the Bösendorfer 225, and he asked me to come have a look at the room. I accepted Mr. Sano's request and immediately went to see the new Ceremore headquarters building, which was still under construction on its site about 2 km. (1.24 miles) north of the Tachikawa train station, in a Tokyo suburb.

<< The Concert Hall's Original Construction Specifications >>

The space intended as the concert hall for the new piano was originally designed as a rectangular, multipurpose conference room measuring 8 m. (26.25 ft) wide by 15 m. (49 ft) deep, with a 3 m. (10 ft) high ceiling. Windows line the east and south walls, and the west wall separates the hall from an office. The hall's entrance is at its north end, where it opens onto an elevator foyer and the elevator that provides access to all floors in the office building.

The room's walls were built of double-layered, 12 mm. (0.5 in.) gypsum board. This material was not only problematic from the standpoint of sound insulation between the hall and the other office on the same floor due to panel vibration at low frequencies, but was also inappropriate for the interior of a concert hall, which requires sound scattering surfaces. Another obvious concern was the HVAC machinery and ventilation fan above the room's ceiling, neither of which had been installed with any strategy or measures for noise abatement.

My first step was to put a temporary halt on the construction work. Then, we developed an acoustical design for the room that could be accomplished by the building's scheduled completion date of April 26, 2004.

<< Materials and Equipment Issues in the Original Construction Design >>

Our acoustical measurements showed low frequency reverberation time is short compared to the middle frequency range due to the panel vibration of the gypsum board. On the other hand, mid-frequency sound exhibits a peaked reverberation characteristic. Therefore, one goal of our design was to reduce the vibration of the gypsum boards.

For the HVAC noise concern, we determined that even at low power, the air conditioner would produce noise louder than NC-40, and there was no way to mitigate the level of noise produced. On the other hand, by creating a sound-absorbing chamber above the ventilation fan, we predicted that when run on its low setting, the fan's noise level would stay below NC-30.

Another equipment and materials concern was the lighting for both the stage and seating areas. In halls of this scale, the two areas most frequently neglected are sufficient air ventilation and lighting for the performers. In Ceremore Concert Hall, we did not have the option of embedding lighting in the ceiling because of the negative impact that would have on sound insulation of the HVAC and ventilation equipment overhead. We resigned ourselves to the alternative lighting solution of adding an open-grid suspended framework about 30 cm (11.8 in.) below the ceiling and attaching the lighting fixtures to this ladder-like grid.

<< Our Acoustical Design Solutions >>

To improve the rigidity of the wall surfaces, we added two more layers of drywall to both the walls and the ceiling and we used nails to firmly attach the layers to each other and ensure their combined stiffness. We located the stage at the south end of the room, giving it a depth of 3.5 m. (11.48 ft). At both right and left stage "wings," we installed gently curved, convex panels to provide sound-reflecting surfaces, and we allowed for open space both on each side of the stage and at the rear of the stage (behind the piano). On the left side of the hall, we covered the glass windows with a fishnet-style curtain to soften the sound reflections as well as a thicker curtain that shuts out light from outside when a darkened hall is desired. On the hall's right wall, we built protruding sections to create a sound-diffusing wall, alternating these sections of the wall with absorbing sections made of wood ribbing backed with glass wool. In order to decrease the low-frequency sound absorption of the sound-absorbing sections of this wall, we used 25 mm. (0.98 in.)-thick glass wool and placed it directly against the wall surface, leaving no air-space between the wall and the glass wool, and we installed the ribbed wood finishing material to press firmly on the glass wool. We carefully determined the specific placement and distribution of these sound-absorbing wall sections along the right side of the hall.

<< Special Attention for the Sound of the Bösendorfer >>

During our design work, we also paid special and separate attention to the needs of the Bösendorfer 225 piano. The question that we posed for ourselves was how to bring out this piano's distinctive aromatic acoustics in a hall that has a capacity of less than 100 persons and a low ceiling. Addressing the hall's acoustics from the perspective of this question required different considerations than the task of creating good acoustics in the hall.

We would have preferred to include the selection of the hall's audience seating as a factor in addressing the Bösendorfer piano's acoustical needs, but the chairs for the hall had already been ordered when we began work on the project. Additionally, there was no way for us to learn the sound absorption characteristics of the already-ordered seating.

<< The Acoustical Design Construction Implementation >>

In developing our design solution, we focused on achieving balance among two categories of elements: the balance of low, mid-range and high frequency sounds, and the balance of sound reflections along the length of the hall, across the width of the hall and vertically from floor to ceiling. We decided to begin with an installation that includes liberal use of sound absorption, creating more sound-absorbing surface area than we hoped would prove necessary, and we scheduled our final decisions on quantity and placement of the sound-absorbing surfaces to wait until after we could hear the piano in the hall and have actual results regarding its unique acoustical characteristics.

Scenery of Test Performance
On June 10, we took acoustical measurements in the hall and adjusted the placement and quantity of the sound-absorbing surfaces. In parallel with our measuring work, we engaged pianist Yuko Hisamoto to perform on the Bösendorfer and we used both the quantitative, physics-based acoustical measurements and our subjective hearing of the piano's sound to determine the best location and quantity of sound-absorbing wall sections. However, our intention to work in the true hall environment was hampered on this day because the hall's audience seating did not arrive in time, so that substitute seats were used instead, and the piano was not yet fully tuned. As a result, even though we proceeded with our decision-making as scheduled, we deferred a decision on the hall's permanent arrangement until we can do more acoustical fine-tuning with the hall's chairs in place and the piano fully tuned.

Using a total of 11 sound-absorbing panels, we tested the hall's sound with all of the panels open (sound-absorbing) and all of them closed (sound-reflecting), and through some additional experimentation, arrived at the currently used arrangement of having only two sound-absorbing panels (located on the stage wall) closed so that they reflect sound instead of absorbing it. With this arrangement, the hall's reverberation time measures 0.5 seconds (at 500 Hz in an unoccupied hall), and the hall's acoustics are characterized by some lift in the low and high frequencies.

When the piano is fully tuned we plan to reevaluate the arrangement of the sound-absorbing surfaces based on the hall's acoustical characteristics and how the piano sounds in the hall. We expect that we will be able to reduce the number of sound-absorbing surfaces needed to half the current number.

<< The Hall's First Concert and Future Objectives >>

Ceremore Concert Hall Musashino held its first concert for a public audience on June 27, 2004. On this day, the HVAC system proved to be the hall's single big problem. When the air conditioning was turned off to eliminate its noise, the temperature in the hall rose rapidly. This reconfirmed a concern we had that running the ventilation fan without the air conditioning is not a satisfactory HVAC solution during Tokyo's hot summer season.

In addition to resolving this outstanding problem, we have suggested to the client that when the rainy season comes, the rainy streets outside will also be a noise source that the client will wish to have mitigated. When these noise issues are resolved, we look forward to this Bösendorfer-equipped small hall achieving a special place for itself as an often-used and well-attended concert venue.

<< Funeral Parlor Acoustics >>

This article provides an opportunity for me to comment on my experience of the acoustics at funeral parlors in Japan. Overall, my impression of the acoustics at these venues is not favorable. Acoustical design has been noticeably left out of the planning for this kind of space. Ceremore Concert Hall Musashino is not a funeral parlor, but it is my wish that the birth of this new hall will raise the funeral industry's awareness of the value of acoustical design and lead to improvements throughout the publicly used spaces of this industry.

For more information about Ceremore Concert Hall Musashino, contact the hall at +81-120-77-1121.

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Nagata Acoustics News 04-09 (No.201)
Issued : September 25, 2004

Nagata Acoustics Inc.
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