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

Nagata Acoustics News 00-12 (No.156)
Issued : December 25, 2000

Toppan Hall Opens in Tokyo

by Toshiko Fukuchi

The Tokyo metropolis boasts numerous halls designed for classical music, among them Suntory Hall and Casals Hall, as well as other performance venues of varying sizes and shapes. Now another new hall has entered Tokyo's "musical fray". Toppan Hall, a small, 408-seat hall, opened to the public in October 2000.

<< The Site's High Profile Location >>

If you join the often unbroken stream of cars traveling on Tokyo's elevated expressway Number 5, from Ikebukuro toward the city's center, the road makes a wide curve to the right as it approaches the JR Iidabashi Station. To the left of the expressway's curve stands the beautiful glass exterior of Toppan Printing Company's new 21-story, oval-shaped Koishikawa Building. People driving towards downtown from Ikebukuro view this graceful addition to the skyline head-on before they follow the road's curve to the right.

<< Project Overview >>

Toppan Printing planned and built this new building (named after the neighborhood in which it is located) to commemorate the 100-year anniversary of the company's founding. Construction was completed on April 7, 2000, including both a high-rise office tower and a low-rise museum wing. The office tower faces the Kanda River that runs underneath the Number 5 expressway and the museum wing stands behind it, making for a smooth segue to the low-rise residential neighborhood adjacent to this side of the site.

Toppan Hall occupies the first floor of the above-ground portion of the low-rise wing, and the wing's basement floor houses the museum. This is Japan's first full-scale museum dedicated to the theme of printing. The architectural firm of Shinichi Okada designed Koishikawa Building and construction responsibilities were shared in a joint venture among Ando, Kajima and Tokyu general construction companies.

<< Pre-opening Inaugural Concert >>

The true date of Toppan Printing's 100th anniversary was June 2, 2000. To celebrate the occasion, a pre-opening inaugural concert was held on the exact date of the anniversary. The program began with a "Sound Arrival Ceremony," followed by the performance of an orchestral work commissioned for the occasion and Mozart's symphony no. 41, "Jupiter."

The Sound Arrival Ceremony created an opportunity for the hall's owner to metaphorically breathe life into the new hall. Toppan Printing's then company president, Mr. Hiromichi Fujita (now the company's chairman) conducted the New Japan Philharmonic Orchestra in a performance of Tetsuo Tsukahara's fanfare, "Igen" ("Majesty"). Following this ceremony, the New Japan Philharmonic debuted the commissioned work, "Prelude for Celebration," composed and conducted by Shinichiro Ikebe. The final work of the evening was conducted by Maestro Ken Takaseki and also performed by the New Japan Philharmonic.

During the remaining months between the inauguration and the official October opening of the hall, a limited number of events were held in the hall, including observation tours by individuals and groups who have a connection with the project or the owner, and concerts for Toppan Hall Club members and for residents of the neighborhood next door. The official opening of the hall to the general public took place on October 1, 2000 and featured a program performed by the Tokyo Quartet.

<< Toppan Hall Interior >>

"Toppan Hall"
Toppan Hall's interior makes extensive use of natural wood materials. The walls are paneled in cherry and the floor is made of Chinese quince wood, creating an overall ambiance of warmth in the hall. To provide sound diffusion, we selected ribbed wood paneling for the wall areas around the stage and the audience seating. For the ceiling material we used fiber-reinforced concrete, again ensuring sufficient sound diffusion by planning a mix of concave and convex variations in the ceiling surface. The visual appearance of both the walls and ceilings is of undulating curves rather than straight lines. This approach is the contribution of the hall's advisor who participated in the early planning stages of the hall. To implement the advisor's intent, we avoided creating any sharp or pointed edges anywhere in the hall's interior surfaces, including both the shapes of the walls and ceilings and even the backs of the chairs of the audience seating, which are rounded rather than square.

<< Toppan Hall's Sound Isolation >>

Toppan Hall is located on the building's ground floor, above the basement-level Printing Museum and below a second floor that is occupied primarily by a coffee shop, restaurant and kitchen. The hall's location required that we consider both how to keep the adjacent floors' noise out of the hall and that we prevent sound produced in the hall from being heard in the museum or restaurant areas. To these ends, we designed a floating construction for the hall, using a rubberized anti-vibration material. We also used glass fiber under the floor of the second story's kitchen to create a floating floor. As a result of these design measures, we achieved sound insulation performance better than 90 dB (at 500 Hz) for each of the floors, enabling the hall, museum, and restaurant areas to all be used simultaneously.

<< A Specialty Concert Hall with Unique Dimensions >>

Toppan Hall was designed as a specialty hall for the performance of classical music and, in particular, for recitals and chamber music ensemble programs. From a plane perspective, the hall has a rectangular configuration. However, because the area behind the stage is slightly narrowed and because there is not too much difference between the width and length of the hall, Toppan Hall does not give visitors the impression of having a traditional shoebox concert hall configuration.

<< Working with Ceiling Height Limitations >>

In addition to the hall's non-standard rectangular dimensions, the height of the room is less than would usually be considered acceptable for a concert hall. Toppan Hall occupies one floor of a multi-story structure, and has a maximum ceiling height of 9.5 m (31 ft). Achieving even this ceiling height was one of the central issues of this hall project both during the design and drawing stages, and during actual construction as well.

The first reason for the hall's height limitations came from the building's location next to a residential neighborhood. Because the exterior height of the structure was limited, our key to achieving maximum ceiling height was to minimize as much as possible the space needed above each floor's ceiling. We worked with each of the project's construction subcontractors to shave off every millimeter they could spare, and we had the suppliers and builders of functional equipment pare down the space they required.

In our efforts to obtain every possible millimeter of height for the hall, we received the largest contribution of ceiling space from the HVAC ducts. Instead of locating HVAC ducts in a deep space above the ceiling, as is usually done, supply air grilles were placed under the audience seating and in the hall's walls, and the exhaust circulation path relies on an above-ceiling plenum strategy. Eliminating all HVAC ducts from above the ceiling, provided most of the space that enabled us to eek out the 9.5 m of ceiling height for Toppan Hall. We gained an additional minor contribution of space by skimping on headroom for the catwalks above the ceilings. They can only be navigated with bent backs. Nevertheless, it is thanks to the concessions made by subcontractors and vendors who normally "rule" in the realm of above-ceiling space that we achieved the ceiling height we did for Toppan Hall.

<< Hall Acoustics >>

One of Toppan Hall's most notable acoustical attributes is the installation of a substantial apparatus that enables a range of reverberation time settings. Even within the somewhat circumscribed genre of classical music, sound volume and quality vary greatly among piano, percussion, wind instrument and vocal performances. The number of performers can be as few as one soloist for a recital to as large as a chamber orchestra. In addition, while the hall may be designed specifically for classical music performances, every hall becomes the location of a ceremony or is used for a pre-concert talk or other speech at some point in time, so we needed to ensure that Toppan Hall's acoustics are ready for all of these events and occasions. By installing apparatus that adds reverberation-time options, we gave the hall flexibility in responding to the needs of different kinds of performances and performers. The variable reverberation time can also be used to adapt the hall for clear speech reproduction. The apparatus can be opened to a maximum angle of 90. When the reverberation time apparatus is completely closed, Toppan Hall's reverberation time is 1.4 seconds (at 500 Hz, with the hall fully occupied). As the reverberation time apparatus is opened, the hall's reverberation time becomes shorter. When the apparatus is opened to its maximum 90 angle, the reverberation time is 1.1 seconds (also at 500 Hz, with the hall fully occupied.)

<< Sound System Speakers >>

In addition to reverberation time, two other requirements for speech clarity in a hall are appropriate selection of sound system speakers and their proper placement. In Toppan Hall we adopted the use of multiple small speakers installed at dispersed positions in the hall's ceilings. Through the use of delay system adjustments, we successfully established the stage area as the sound image source, despite the dispersed positions of the speakers. We also found that this sound system sends clear speech throughout the hall even when the reverberation apparatus is closed and the reverberation time is 1.4 seconds.

<< Hall-sponsored Concert Programming >>

Toppan Hall sponsors concerts that promote at least one of the following:

* Increase the number of classical music fans

* Discover and nurture young talent

* Contribute to the community and society.

Four advisors to the hall decide which concerts and programs the hall will sponsor. Examples of ongoing concert series include matinee performances titled "In Pursuit of a Theme," that start at 2:00 in the afternoon, and "Debut Concerts 12:15," another series of mid-day concerts featuring new artists. Japanese readers can access the hall's complete calendar at http://www.toppan.co.jp/hall/.

<< The New Hall's Reputation >>

Toppan Hall quickly earned a positive reputation among both performers and audiences alike. The small size of the hall means that audiences do not hear any displeasing drop-off in sound. Listeners who prefer the lushness of a long reverberation time may be less than satisfied with this hall, but concertgoers who enjoy listening to the fine nuances of a performance will be happily rewarded by the sound Toppan Hall delivers.

In this intimate setting, the audience can watch the expressions of performers' faces and follow the movements of their fingers and hands, a kind of concert experience unachievable in larger concert halls. I hope that Toppan Hall will continue to sponsor concerts that will give both artists and audiences many fine opportunities to enjoy the hall's warm and intimate personality.

Improving Voice Amplification in a Large Training Facility

by Katsuji Naniwa

A certain corporation recently built a large training facility in Japan, but was dissatisfied with the level of clarity obtained in the speech intelligibility capability of the facility's largest training hall. The architectural design firm connected with the project asked Nagata Acoustics to diagnose the problem, design a sure remedy and oversee its implementation. This article presents some of my findings and experiences from serving as lead acoustician on this remedial project.

<< Project Background >>

Usually, it is the project owner who retains Nagata Acoustics to solve this kind of a post-construction complaint. However, in this case, the problem was apparently identified simultaneously with the completion of construction, and the architect requested our help. Several strategies had already been attempted by the time the architect first spoke with Nagata Acoustics. As none of these attempts had eradicated the problem, the architectural firm told us that they were prepared for the likelihood that any successful remedy would involve major renovation.

The training hall with the problem is rectangular in shape, and has a capacity for some 300 persons when set up with rows of tables behind which the training participants sit. The hall can be divided into two smaller halls using a sliding partition wall, and each half of the hall has a video screen and a lectern. On each side of the video screen are two main speakers, installed flat and exposed against each front wall. In addition, the ceilings of each half of the hall are equipped with four rows of three medium-size ceiling speakers each, for a total of 12 ceiling speaker units. Each of the ceiling speakers contains a small horn as well.

The sound absorbing surfaces of the training hall interior included the ceiling's mineral fiber acoustical panels and the carpeting covering the training hall's floor. The hall's reverberation time was slightly longer than is desirable for the hall's intended purpose.

<< Investigating the Cause of the Problem and Project Scope >>

My first step was to investigate the extent of the problem and make a decision as to whether a major renovation effort was the only possible solution. Viewed from another angle, I posed the question of whether acceptable clarity could be obtained by making adjustments to the existing sound system and replacing some of the equipment, as this would be a much less costly and less time-consuming strategy. My investigation included the following steps:

* I tested the sound system under normal use conditions.

* I checked the performance of each speaker individually.

* I measured if any improvement in clarity was obtained using different kinds of microphones.

* I confirmed whether moving any or all of the main speakers impacted the affect that long-path echoes off the rear walls and flutter echoes off the side walls had on the clarity of the sound amplification.

* I tested how moving each of the dispersed ceiling speakers affected the sound quality as well as how changing the placement of all of the ceiling speakers affected the sound quality.

* I tested for acoustical feedback when the stage and audience microphones were placed in a variety of locations.

* I measured the hall's reverberation time and confirmed its affect on the clarity of amplified speech in the hall.

<< Sample Worst Case Scenarios >>

Before sharing the findings of my investigation, I will describe two examples of situations that would require major renovation in order to obtain reinforced speech intelligibility. One example is a situation in which the primary reason for the lack of clarity is too much reverberation. The remedy for this kind of situation calls for major interior renovations that would include adding sound absorbing and sound diffusing materials and elements. Because these changes might impact the feel of the hall from an architectural perspective, they would require the time and money to study implementation options in addition to considerable construction costs. Moreover, the hall would need to remain closed during the renovations, a requirement that some clients would deem the most painful expense of all.

The second example of a situation that would require major renovations is when a hall's current sound system cannot be used as the basis for a major overhaul. If the entire sound system must be scrapped and an entirely new one installed, then major construction becomes necessary and the same time and money expenditures apply as in the example above, including lost use of the hall or room for some period of time.

<< My Conclusions from Investigating the Training Hall's Problem >>

Luckily for the owner and architect of the training facility described earlier in this article, my investigation of the training facility's speech intelligibility problem led me to conclude that the problem could be solved without major renovations. I based my decision on the following conclusions.

* While the room's reverberation time is longer than would be ideally desirable, it is considerably shorter than the reverberation time of a church or a concert hall with a pipe organ. Because the training room has a high ceiling, the room's side walls work as large sound-reflecting surfaces, and I understood this to be the reason that flutter and long path echoes were so audible. However, I did not think that either the reverberation time or the echoes were creating enough of a problem to be the cause of the lack of speech intelligibility.

* The main speaker system installed on either side of the video screens is a brand and model having appropriate performance characteristics for the size and purpose of the large training hall. However, the placement and angle of the speakers needed correction. The two speakers on each side of the video screens were placed one on top of the other, with the higher speaker pointed toward the rear wall of the training hall, and the lower one pointed toward the front and center area of the audience (participant) seating. I determined that this positioning was the cause of the echo from the rear wall and also the cause of acoustical feedback. Because these speakers are simply mounted onto the training hall walls, changing their positioning could be easily accomplished.

* The room produced a "booming" phenomenon and I concluded that this was another major cause of the lack of speech intelligibility. Adjusting the output of the sound system speakers would solve this problem.

* When I tested alternate positioning of individual ceiling speakers, I created a minor "booming" effect and other negligible negative results. When I changed the positioning of all of the ceiling speakers, the negative impacts became noticeable and convinced me that the room's ceiling speakers have a major impact on both the volume and reinforced speech intelligibility in this room. As is true for the previous point, this problem could be solved by adjustments to the training hall's current sound system.

<< This Case Study's Happy Solutions >>

Using my above conclusions, I proposed a remedial strategy that had as its primary component precise adjustments to the training hall's sound system. Since major construction would not be required, my proposal was readily accepted and implementation proceeded with alacrity. Below are the changes we made.

* When the main speakers are used, we angled them slightly downward to avoid creating an echo off the back wall. In addition, by adjusting the level of specific sound frequencies that produce booming, we produced speech amplification that has no clouding in the lower registers and substantially improved the clarity of higher register speech. Additionally, we made an adjustment to compensate for the natural degrading of higher register sounds, and this further improved the reinforced speech intelligibility.

* When all of the ceiling speakers are rotated in specific directions, overlapping of lower register energy exacerbated and distorted lower frequency sounds. By dampening these frequencies, we eliminated the booming phenomenon and assisted with the compensation for natural degrading of the higher frequencies. These adjustments resulted in a major improvement in the reinforced speech intelligibility.

* When microphones are used at the stage podium or from the audience area, we adjusted the sound system to reduce frequencies that are likely to produce a acoustical feedback, thereby making microphone use more effective and pleasant for listeners.

* Regarding the choice of microphone equipment, we compared the training facility's equipment with other equipment that has an excellent reputation for clear speech and learned that the hall's equipment is lighter and emphasizes low register sound less than the more popular brand. Accordingly, we made no changes to the microphone equipment.

* My investigation included gathering comments from people who had experienced the hall's speech intelligibility problem. The comments revealed that residual noise from the sound system was also a problem. To alleviate the noise as much as possible, we readjusted the equipment's gain, setting it downward sufficiently to eliminate this problem.

* The anti-feedback device in the training hall's sound system changed the frequency it controlled whenever a microphone was moved or its angle changed, resulting in very unnatural-sounding voice reproduction. Because of this negative affect, we decided to deactivate the anti-feedback function of the device.

After completing the above changes and adjustments, speech intelligibility in the large training hall of the facility was markedly improved. I confirmed with the facility's manager that the speech intelligibility is now satisfactory. My investigation and successful non-major remedial strategies saved the company from spending the more than \10million (~US$90,000) that it had budgeted to fix the large training hall's increased speech intelligibility problem.

<< Completion of Construction May Not Mean Acoustical Completion >>

As this case study shows, the completion of construction for a hall or other facility does not necessarily mean that the acoustical engineering and consulting is also complete. Human ears must listen to the sound system in its installed environment and tune the equipment for optimal results. Intensive, professional listening and analysis of the sound system molds its character and gives the hall or facility its musical soul. The general contractor may complete a project and conduct the required measurements and inspections, but these should not be the final tasks before a hall or sound-system-equipped facility opens.

The settings for today's sound systems, and their operation, are more complex and require more expertise than ever. Concert halls may employ professional sound system technicians, but corporate and other facilities such as the one described in this article typically rely on employees who have no sound system expertise to operate their complex sound systems. To hand-off such complex equipment that requires delicate and precise adjustment to untrained personnel is unwise. The final acoustical tuning is an essential and important last step in preparing these facilities for successful use. Nevertheless, I know that understanding and acknowledgement of the value of this last task continues to be overlooked. Hopefully, this case study will convince at least a few more readers to prioritize the final acoustical tuning in all their projects.

Nagata Acoustics Moves to New Main Office and Opens US Branch

by Hideo Nakamura

In January 2001, Nagata Associates will relocate our Tokyo main office to the address below. Our telephone and fax numbers will also change. (These will become available at a later date.)

<< New Tokyo Main Office >>

Our new main office location is a short, four-minute walk from the Marunouchi Subway Line's Hongo 3-Chome Station. Our offices will be in a building adjacent to Hongo Church, on a tree-lined street with the kind of quiet and serenity many people might think has disappeared altogether from the sprawling Tokyo metropolis. At the entrance of our office stands a beautiful old maple tree designated as a protected tree by Bunkyo Ward, and there is plenty of greenery in the views from our office windows. We look forward to continuing our acoustical consulting work with fresh energy and spirit in our company's new home. The new office will open on Monday, January 15, 2001.

Tokyo Main Office:
Nagata Acoustics
Hongo Segawa Bldg. 3F
2-35-10, Hongo
Bunkyo-ku, Tokyo 113-0033
Tel: +81-3-5800-2671, Fax: +81-3-5800-2672

<< US Branch Office >>

In keeping with the growing international focus of our business, and our increasing participation in projects in the United States and other countries other than Japan, we recently opened our first overseas office. The new US Branch Office is located in Santa Monica, California. This office will take immediate responsibility for the ongoing Walt Disney Concert Hall project, as well as for the other projects in the United States in which we are presently engaged.

US Branch Office:
Nagata Acoustics US Office
201 Ocean Avenue, Suite1205B
Santa Monica, CA 90402
Tel: +1-310-451-6230, Fax: +1-310-451-6230

All of us at Nagata Acoustics look forward to welcoming you to both of our new offices whenever the opportunity arises.

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Nagata Acoustics News 00-12(No.156)
Issued : December 25, 2000

Nagata Acoustics Inc.
Minami-Shinjuku-Hoshino Bldg. 8F, 5-23-13
Sendagaya, Shibuya-ku, Tokyo 151 Japan
Tel: +81-3-3351-2151, Fax: +81-3-3351-2150

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