Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 11-03 (No.279)

Issued : March 25, 2011

[ Japanese Version ]

Dear Our Friends,

From 11th March 2011, at the disaster of the large earthquakes and the most enormous tsunami in the wide areas of the northeastern Tohoku region as well as areas around Tokyo, we've got a lot of encouragement from all over the world. The staff of Nagata Acoustics Tokyo are all safe and sound. We greatly appreciate for your warm considerations and supports. Thank you very much indeed.

Kanagawa Arts Theatre and New NHK Yokohama Broadcasting Station Open in Yokohama's Yamashita-cho

by Ayako Hakozaki

In 2009, Yokohama City celebrated the 150th anniversary of the port's opening and the beginning of international travel and trade through this gateway to Japan. As the anniversary year approached, the city and prefecture put a great deal of effort into renewal initiatives that improved, preserved, restored and modernized many destinations and points of interest frequented by both tourists and local residents. In particular, projects gave a face-lift to Zou-no-hana (literally, "elephant's trunk") Park, Yokohama Marine Tower. The city made Osanbashi Yokohama International Passenger Terminal to Yamashita Park and the Motomachi neighborhood. Gaps between destination points of interest became connected through new development, refreshing the entire area for all visitors.


On the heels of the anniversary year development, in January, 2011, between Yamashita Park and Yokohama's Chinatown, a new project completed near Kanagawa Prefectural Civic Hall. The new structure, which combines Kanagawa Arts Theatre (KAAT) and NHK Yokohama Broadcasting Station under one roof, adds yet another exciting reason to spend time in this part of the city. The building is a short, about five-minute walk from either Nihon-Odori Station or Motomachi-Chinatown Station on the Minatomirai Subway Line.

<< The KAAT and NHK Project: Part of a Larger Development Plan >>

The new building uses parcels of land in the Yamashita-cho neighborhood where the Kanagawa Dome Theatre (built in 2000 and closed in 2005) and a Kanagawa prefectural administrative building stood previously. The land belongs mostly to the prefecture.

The redevelopment plan divided the area into three sections (A, B1 and B2). Section "B1" is located between the other two sections and designated for KAAT and NHK. The redevelopment plan reserved the two adjoining land parcels "A" and "B2" for private development. The plan pursued initial phases of work toward the goal of developing new structures compatible with the surrounding existing buildings and the leisure-time, destination nature of nearby businesses while creating an urban design that respects the remaining historical architecture. The downturn in the economy impacted the privately funded portion of the redevelopment plan and the the "B1" section was opened first.

<< KAAT and NHK Yokohama Broadcasting Station Project Overview >>

The structure that houses KAAT and NHK Yokohama Broadcasting Station has an atrium that rises to a height of 30 m. (98 ft) flanked on two sides by a larger and smaller portion of the building. The larger portion of the building houses the broadcasting station on levels one through three, with the KAAT main hall starting on the fourth floor. The smaller portion of the building has four KAAT studios, stacked vertically.

The project's client was Urban Renaissance Agency Kanagawa Regional Branch Office. The project's major participants included a consortium of Hisao Kohyama Atelier and APL Associates (Hidetoshi Ohno and Architecture Planning and Landscape Design Workshop) as the architects and Kajima Corporation as the general contractor. Nagata Acoustics served as the project's acoustical consultant, providing room acoustical design as well as sound isolation and noise control design services. In addition, the project received valuable expert advice from Tokyo University Professor Emeritus Masahito Yasuoka regarding the subway noise and vibration reduction strategy.

<< NHK Yokohama Broadcasting Station >>

Until moving into the new building, NHK Yokohama Broadcasting Station was located just down the street on Honcho-dori in a building constructed 47 years ago. NHK's personnel moved into the new building as soon as occupancy became possible. They began broadcasting from the new building on November 27, 2010.

With a slogan that translates roughly as "Exciting and Connecting", the new broadcasting station adds space for the general public to visit without the need to make advance reservations or attend a formal tour. The new space, named "NHK Heart Plaza", includes an interactive broadcasting area and a library of NHK programs. The inviting design makes it easy for passers-by to take advantage of this opportunity to learn more about broadcasting and NHK.

<< Kanagawa Arts Theatre >>

Kanagawa Arts Theatre (KAAT) has a main hall (1,300 seat capacity in its largest audience configuration), a large studio with movable stadium seating and movable seating units that can seat an audience of 220 and converts from stepped seating to a flat-floor configuration, a medium and a small studio suite "A" that has a movable, sound-isolating partition wall, and a small studio "B" that has an adjoining roof-top terrace. KATT will be managed as a part of Kanagawa Prefectural Civic Hall, which is located adjacent to the KAAT building (on the side of the KATT building that faces toward Yokohama Port). The civic hall has a main hall with 2,488 seats and a small hall with 433 seats. The main hall will be used for large-scale productions such as grand opera and ballet productions, and KATT will be used for plays, musicals, dance concerts and similar genres. Together, KATT and the civic hall can offer the right size venue for each performing art genre.

<< KATT's Horseshoe-shaped Theatre >>

The theatre's configurable main floor audience seating-steep slopel
steep slope

The theatre's configurable main floor audience seating-regular slope
regular slope

KATT's main venue is its horseshoe-shaped, three-balcony theatre. In this theatre, we were able to keep even the most rear seats only 25 m. (82 ft) from the stage for a sense of intimacy with the stage from every seat. A key feature of this hall is the spiral lift mechanism used to alter the slope of the main floor's audience seating. The mechanism can raise the height of individual rows and thereby change the slope of the main audience seating section. This main section can be configured as flat-floored seating, raised to its regular position which has the most rear row of seats at the same height as the first-tier balcony or raised and expanded to a steeper slope so that the last row of the main audience seating connects to the first row of the second-tier rear balcony.

The acoustical design for this theatre prioritized actors' clarity of speech and, therefore, the stage does not have a sound reflection panel system. We designed the ceiling to have a sequence of connected curved panels from the front to the rear of the theatre and eaves at the front sides of the stage and at the side balconies that send early sound reflections to the audience seating.

<< Sound Isolation Design and Strategy for Subway Noise and Vibration Reduction >>

The new KAAT - NHK building has a diverse variety of rooms serving very different needs all contained within a single structure. The multiuse nature of the building required us to give high priority to sound isolation planning and design for the entire building. In addition, because the Minatomirai Subway Line travels under the street in front of the building, we also prioritized designing and implementing a strategy to mitigate noise and vibration from passing trains.

We achieved high performance sound isolation between KAAT's theatre and studios, as well as between broadcasting studios by specifying anti-vibration and sound isolating designs and materials. To decrease noise and vibration from trains on the Minatomirai Subway Line, we devised an anti-vibration and noise isolating structural design for the performance spaces. Our design takes into account the anti-vibration benefits of the seismic isolation structural design implemented for the entire building.

<< Director Amon Miyamoto Becomes First KAAT Artistic Director >>

KAAT summarizes its mission as "three kinds of creating": (1) creating "stuff" in the form of performing arts productions that will be sponsored and produced in-house; (2) creating "(skilled) people" by providing programs that train and nurture stage technical professionals and arts management professionals; and (3) creating community through the work of NHK Yokohama Broadcasting Station and by collaborating with nearby cultural institutions to create exciting and attractive programs. KAAT wants its theatre to have the edginess of urban cultural hubs where audience patrons can chance upon new and exciting performances and events whenever they come to the theatre.

In 2010, director Amon Miyamoto accepted KAAT's invitation to become its first artistic director. For KAAT's official opening on January 29, 2011, the program featured a play adaptation of Yukio Mishima's novel "Kinkakuji" ("The Temple of the Golden Pavilion") directed by Mr. Miyamoto.

Mr. Miyamoto, who is well known in European, U.S. and Japanese theatre circles, gave many media interviews in advance of KAAT's opening. He has been outspoken about wanting everyone on KAAT's staff to express their ideas and actively communicate with each other not only about artistic and production matters, but also about all aspects of KAAT's work and operations.

At Mr. Miyamoto's installation as KAAT Artistic Director, he spoke very movingly about his vision for the theatre's role in today's society, saying that through theatre and art we can come in contact with different kinds of people and diverse ways of thinking, and that this expands our possibilities as human beings. He added that, in today's Internet society, he feels especially strongly that productions of plays and other theater genres have expanding possibilities precisely because they are live performances.

KAAT's calendar of performances is already building diversity into the theatre's programming. This season's performances include musicals, drama, Bunraku (Japanese puppet theatre) and other puppet theatre, Japanese comic raconteurs and other genres. KAAT is a wonderful place to feel the energy of live performing arts. For more information visit the KAAT Web site.

The Screening Room in Nippon Cine Arts' New Tokyo Headquarters "Arbre d'Or Ichigaya"

by Toshiko Fukuchi

Nippon Cine Arts' new screening room
Nippon Cine Arts' new screening room

Nippon Cine Arts Co., Ltd was founded in 1951 in the Kanda section of Tokyo and is one of Japan's oldest and most well-respected film subtitle companies. In 1961, the company moved to its present Ichigaya location. After nearly 50 years in its Ichigaya building, the company decided to rebuild its headquarters. The new building, renamed "Arbre D'Or Ichigaya" (abbreviated as "AD Ichigaya Bldg") completed in September, 2010.

<<Overview of the New AD Ichigaya Bldg Project >>

The architecture of most of the buildings in AD Ichigaya Bldg's neighborhood indicates their recent vintage. The old Nippon Cine Arts' building was the last remaining structure built in an architectural style that evoked the previous century's Showa era (1926-1989). AD Ichigaya Bldg has a glass exterior and an architectural design in keeping with the contemporary look of its neighbors.

The new company building has 11 levels above ground and 1 basement level. The new screening room occupies the basement level and company offices fill floors 2 through 11.

Ar.Partners architectural design studio served as the project architect and Hazama Corporation built AD Ichigaya Bldg. Nagata Acoustics provided room acoustics, sound isolation and equipment noise control consulting services. Ar.Partners' founding architect, Mr. Yuichi Kikkawa formerly worked for Mayekawa Associates and I collaborated with him on an auditorium project for Kunitachi College of Music while he was employed by that firm. Thereafter, Mr. Kikkawa established his own company. I enjoyed the opportunity to work with him again on this project.

<< Screening Room Sound Isolation and Noise Control Design >>

From the beginning of our participation on this project, a key focus of our design work was the very large sound volumes expected to be produced in the screening room. This focus informed our first major decision: where to locate the screening room. We wanted to situate the screening room as physically distant as possible from the building's offices, so we decided on the basement level as the best location.

In addition, because the Namboku Subway Line runs directly below the street in front of AD Ichigaya Bldg, we designed a noise reduction strategy that implemented an anti-vibration and noise isolation structure to prevent solid borne noise generated by passing trains from being heard in the screening room. Our post-completion measuring confirmed that our design achieved effective sound isolation performance even for sound levels above 100dB (at 500Hz) between the screening room and the closest offices on the second floor. We also ran feature movies in the screening room and confirmed that sound from the movies could not be heard at all in the above-ground offices. Similarly, we confirmed that our design totally prevented sound from nearby subway trains from being heard in the screening room.

<<Reverberation Time and Other Screening Room Design Highlights >>

Nippon Cine Arts' company president Hiromune Kaneki
President Hiromune Kaneki

Another important acoustical design specification was the sound reverberation time, which we set at approximately 0.2 seconds. Our specification and design implementation achieves basically flat sound frequency characteristics through most of the low frequency range.

In the screening room environment, audiences sit without moving for relatively long periods of time while they watch the movie screenings. To provide both a comfortable and energy-saving heating and cooling solution, the project installed a radiant heating and cooling system. For the audience seating, company president Mr. Hiromune Kaneki specifically stipulated that the project install a large-size seat model by the well-known French fixed-seating manufacturer Quinette Gallay. Likewise, the project installed a complete array of high-end equipment representing the most current technological advances, as described in the accompanying table.

<<The Surprising Loudness of Sounds We Hear Every Day >>

Nippon Cine Arts' Mr. Kaneki has an engineering background. During the project, he sometimes visited the job site and showed particular interest in our acoustical evaluation activities. He observed our measuring of the site to gather vibration data and, at the completion of the project, our measuring of the screening room's acoustical characteristics.

Installed Equipment (based on Nippon Cine Arts documentation)

As part of our planning work for this project, we measured the vibrations from the nearby subway line in the company's old building. Our results documented a louder level of noise than Mr. Kaneki and some Nippon Cine Arts employees anticipated. They were surprised to realize that their daily listening to noise from the trains had made them oblivious to it.

In addition to using the new screening room for Nippon Cine Arts screenings, the company often rents the hall to other companies and individuals. We're told that the new, quiet screening room receives excellent reviews from all who use it.

Through its work, Nippon Cine Arts makes the scripts of many European, Hollywood and other films comprehensible to Japanese cinema fans and has created the subtitles for many award-winning movies. For more information about the company and some photos that trace the technical history of this specialty industry, see the Nippon Cine Arts Web site at Nippon Cine Arts Web site (in Japanese).

Giving Sound Reserve Power-A Clue to Outstanding Amplified Acoustics

by Makoto Ino

Recently, in a new, small-scale hall, I experienced the joy of extraordinarily fine amplified sound. At the end of every project, after completing the fine tuning and verifying the performance of the hall's sound reinforcement system, I visit the project site to perform final listening evaluation. I conduct this final test by listening with my own ears. When I listened in this particular small-scale hall, the sound truly exceeded my expectations.

<<Causes of Amplified Sound Quality Problems >>

Before discussing the reason for the excellent sound amplification in the hall I mentioned above, I will review the factors that negatively impact the quality of amplified sound. These include the following:

  • The characteristics of different sound frequencies can cause inconsistencies in their amplification levels and this, in turn, can cause timbre imbalances or sound coloration problems.
  • If connections within the sound system or equipment settings ignore the unique characteristics of each piece of equipment, this causes problems due to the specific timbre balance characteristics, output dispersion patterns and input-to-output linearity of different makes and models of sound system equipment.
  • Sound system equipment settings and connections can cause problems related to the S/N (signal-to-noise) ratio or a misalignment of dynamic ranges.
  • Architectural factors can affect the environment where loudspeakers are installed and positioned, negatively impacting the sound quality.

A Japanese scenographer, Mr. Ichiro Takada, who now currently serves as JATET's chairman, attended OISTT's founding congress in 1968. He and other Japanese theatre technology professionals recognized the need for a Japanese association along the same lines as OISTT and founded Japan's first theatre technology association, the Japanese Institute for Theatre Technology (JITT), in May, 1969, one year after the establishment of OISTT.

<<Fine Tuning of Loudspeaker Coverage >>

As a sound system designer, when I evaluate the loudspeakers' impact on the quality of a hall's sound system, I listen in the room to validate two fundamental criteria: (1) that the loudspeakers are of sufficient number, and installed and positioned to achieve appropriate overlapping of each speaker's effective coverage area; and (2) that the speakers' total effective coverage area extends across the entire audience seating area.

Loudspeaker manufacturer specifications provide data on a loudspeaker's nominal coverage area, calculated based on the distance at which the speaker's sound pressure level (SPL) has decreased by more than 6dB, measured from the speaker's center axis. To evaluate the actual effective coverage area of a sound system's speakers and perform fine tuning of the system, I listen to the installed sound system with my own ears.

Because today's loudspeaker manufacturers focus on achieving superior sound quality and clarity within the speaker's coverage area, it is very worthwhile to evaluate the effective coverage area by listening to the speakers in the locations where they have been installed. Even within the nominal coverage area, the further a listener's location from the speaker's center axis, the more the SPL decreases. The perceived sound quality of the speakers can be improved by adjusting the placements of the speakers so that their center axes face the more distant audience seats.

When designing a sound system installation, the sound system designer uses architectural drawings and geometric calculations to determine the loudspeaker performance requirements and number of units needed. During the fine tuning phase of the project, the designer makes subtle adjustments to the directional placement of the speakers to achieve optimal uniformity of the SPL distribution and the subjectively perceived sound amplification volume. By performing these subtle adjustments, sound system designers have eliminated the possibility of a client discovering insufficient sound volume in one or another part of a hall.

<<Analyzing Why a Sound System Sounds Exceptionally Fine >>

During any sound system project, we arrive at the last fine tuning phase after following processes and procedures step by step in a defined sequence. When we achieve results that significantly exceed our expectations, it is more difficult to figure out what produced the extraordinary results than it would be to find the cause of a problem that needs correction.

Regarding the fine sound amplification in the hall I mentioned at the start of this article, I reviewed the possible reasons for the exceptional results with my colleagues who participated in the fine tuning and listening evaluation of the system. We concluded that the nominal output power (that is, the highest possible output power) of the amplifier is responsible for the fine quality of amplified sound in this hall. Below I explain how we arrived at this conclusion.

Examples of differences in peak SPL depending on the sound source
Examples of differences in peak SPL depending on the sound source

<<SPL, Average and Peak Amplitudes, and the Benefits of Having a Cushion of Amplifier Power >>

The desired SPL at the audience seating differs depending on the sound source. For speech, we target the range of between 80dB and 85dB. For jazz and other popular music genres, we want about 95dB. Rock music needs even louder sound volumes, on the order of 100dB to 110dB. Each of these target values refers to the signal's average effective value. As can be seen in the accompanying graphs (which have all been adjusted to about the same RMS [root mean square] value), if we focus on the difference between the average and peak-to-peak values, we can easily see that the SPL varies depending on the sound source.

At nominal output power, the power amplifier produces sine wave signals characterized by not more than a 3dB variation in the difference between the SPL's RMS and peak values, as shown in the graph. In the hall where I had the exceptional listening experience, the room has a small scale of less than 600 seats and the sound system installation uses high-efficiency loudspeakers. Accordingly, we estimated an average of 80W for the required power of the speakers positioned to cover the rear audience seating. In this setting, a power amplifier rated as having 80W output power suffices to produce sine waves, but for speech and music reproduction, a power amplifier with output power of 400W to 1,280W must be used, because these sound sources exhibit SPL peak values 10dB to 15dB greater than their average values.

In the hall under discussion, the sound system has a 1,000W power amplifier, giving the amplifier a power surplus 12.5 times the estimated required power for the environment. Expressed as extra power in watts, the surplus seems large, but this translates to a difference between average and peak SPL levels of 14dB, a most appropriate SPL cushion.

In this hall, I listened to the reproduction of a live recording CD. The brass, percussion and acoustic guitar all sounded totally natural and the amplified sound filled the entire space. I attribute this delightful outcome to the surplus power of the amplifier.

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 ]