Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS


News 07-05 (No.233)

Issued : May 25, 2007

[ Japanese Version ]

Sonorium Hall Opens in the Tokyo Suburb of Eifukucho

by Akira Ono

Entrance of Sonorium
Entrance of Sonorium

Interior of Sonorium (front)
Interior of Sonorium (front)

Interior of Sonorium (rear)
Interior of Sonorium (rear)

The Keio Inokashira Train Line starts at Tokyo's Shibuya Station and runs west through some of Tokyo's most desirable residential neighborhoods. In April of this year, a new 100-seat hall designed primarily for the performance of chamber music opened in one of these neighborhoods. The location is a convenient 7-minute-walk from the Inokashira Line's 7th stop, Eifukucho Station. The hall's owner named the hall Sonorium, a new blended word coined by combining "sonority" with the Latin suffix "rium," which means place or building.

Sonorium has already been featured in two Japanese architectural magazines, the March 2007 edition of Shinkenchiku and the May, 2007 (Vol. 86) edition of Casa Brutus. The architectural design for Sonorium is the work of Mr. Jun Aoki's atelier. We recently wrote about Mr. Aoki in the October, 2006 issue of Nagata Acoustics News and Opinions, in an article about the Aomori Museum of Art, which he also designed. When Shinkenchiku Magazine ran its feature on Sonorium, the magazine provided a perspective on how the new concert hall fits into the course of the architect's entire body of work, ranking Sonorium among Mr. Aoki's other architectural accomplishments and delving into the conceptual aspects of Sonorium's architectural design.

<< Highlights of Sonorium's Architectural and Interior Design >>

The land on which Sonorium stands is a flag lot in a residential area densely packed with houses mostly built to occupy as much of their properties' land as possible. When visitors arrive at Sonorium, they see a door that faces onto the narrow street in front of the property, and the architectural design is such that they will almost be unaware of the building's exterior as they move from the street into the interior of the concert hall.

Inside, the concert hall has a 6 m. (20 ft) ceiling. Both the ceiling and the walls are white plaster. One small and one large window have been cut into the walls, and our acoustical design gave particular attention to ensuring a high level of sound isolation for these windows in consideration of the nearby neighbors. We fitted the interior and exterior walls with separate, single-pane glass windows and, to maximize the sound isolation performance of the windowed portions of the walls, we created more than a meter (3.3 ft) of space between the interior and exterior walls and angled the interior wall inward towards the interior of the hall so that the two walls would not be parallel. As a result, from inside the hall, the windows look like a white, bright square and rectangle because of the space between the interior and exterior walls and their non-parallel alignment, and the arrangement acts as a sound lock that traps the hall's music while allowing soft natural light to bathe the hall.

This concert hall's unique, slightly asymmetrically irregular shape is a result of the several constraints of the shape of the property and building code limitations on the wall angles, as well as other factors. Through the creativity of the architect, the limitations of the slopes of the windowed walls and the flag lot-shape of the property became opportunities to create Sonorium's enchanting interior. From the room acoustical design perspective, the interior shape works well to prevent undesirable acoustical phenomena such as flutter echoes and booming. The architect's design concept and our pursuit of favorable acoustical room design conditions thus experienced a happy confluence on this project.

As for the hall's flooring, solid wood planks and traditional Japanese joinery techniques were selected for both the stage and audience seating area. Sonorium's owner spent considerable effort to find a wood that would integrate well with other aspects of the interior design. Eventually she found some 200-year-old Japanese red pine ("akamatsu " ) that had been the beams of a torn-down shoya yashiki house. The pine was cut into 60 mm. (2.36 in.)-thick planks for use as the stage and audience area floors.

<< Sonorium's Acoustics >>

In designing the hall's acoustics, we gave strong weight to the client's expressed desire that the hall have a long reverberation time. Through our participation in the selection of the interior space's building materials, including concrete for the interior walls and ceiling, and thick wood planks for the floors, as well as through the selection of audience seating made of exposed wood, we gave the hall an abundance of sound-reflecting surfaces—while specifying a sound-absorbing material for just one portion of the interior walls.

Sonorium's reverberation time measures 1.3 seconds (at 500 Hz) in an unoccupied hall which. For a hall of Sonorium's spatial volume, the reverberation time is comparatively long. Based on the measured value, we extrapolate a reverberation time of 0.7 seconds (at 500 Hz) when the hall is fully occupied with an audience of 100 persons.

The hall's irregular shape eliminates the propagation of undesirable acoustical phenomena that might otherwise be a concern in a hall of this size, but the small volume of the space did require us to devise means to diffuse and disperse the sound to soften the powerful sound reflections as they bounce off the room's walls. To this end, we specified that the finish of the walls' plaster be rough rather than smooth, and relied on this element to diffuse and disperse the sound reflections.

<< Sonorium's Celebratory Opening Concerts >>

On April 3, 2007, Sonorium's opening was celebrated with a chamber music concert by cellist Hiroyuki Kanaki and pianist Kazune Shimizu. On April 20, a second opening celebration concert featured pianist Yukio Yokoyama in a recital performance.

During the chamber music concert, the melodic line played by Mr. Kanaki on his cello seemed to work like a charm awakening the Japanese red pine planks from a long sleep and enlivening them with new energy that filled the hall with the cello's wonderful resonance. Moreover, the hall's long reverberation time and the walls' sound reflections did not impair the sound of the piano, as both performers understood the sound environment well and used the hall's acoustics advantageously to achieve stunning performances.

Our client for this project—and Sonorium's owner—is Ms. Shizuyo Kusunoki, a successful copywriter and creative director whose commercials and magazine work is well known in Japan. Through her work she has made many friends among the ranks of Japan's most accomplished and famous musicians, many of whom flocked to Sonorium's opening concerts. Now Ms. Kusunoki intends to expand her career beyond advertising planning and production to apply her creative and entrepreneurial acumen to concert hall operations, CD production and public relations management of musical artists. We can surely look forward to Sonorium being a venue where both professional and amateur musicians enjoy the hall and the performances that will be held here.

Installed Sound Systems/ Part 3: Loudspeakers and the Total Hall Environment

by Makoto Ino

Covered loudspeakers
Covered loudspeakers

In this third segment on the topic of installed sound systems, I would like the reader to join me in surveying the environments in which hall loudspeakers are selected and evaluated, followed by a look at the physical environment constraints that currently affect hall loudspeaker performance. In the most simplified terms, the planning activities for a hall sound system determine what equipment the hall needs and how to install it. Yet, as we delve into the details of these decisions, the factors to consider grow significantly.

<< Criteria to Consider in Sound System Planning >>

For a hall's sound amplification needs, we must set goals for sound volume, sound quality, sound imagery and sound clarity in relationship to the intended performance genres and other aspects of how the hall will be used. Other factors we consider are:

  • Who will how operate and maintain the sound system?
  • What initial and future costs can the hall afford?
  • What interior design constraints has the architect imposed on the loudspeakers?

Planning the sound system design requires balancing decisions that can be made based purely on physical properties and characteristics against aspects of the project that rely on subjective interpretation. Sometimes, the technological best path and subjective considerations do not easily align.

Every sound system project has both objectives and constraints. Based on an understanding of both of these factors, the sound system design maps a clear plan for the equipment selection and installation details to realize the objectives, taking the constraints into consideration. Chronologically, the architectural design and operational programming precede the sound system design, and set the conditions and many of the constraints. Concurrently with these planning efforts, the construction estimating and budget proposal processes also contribute to charting the course the sound system design will take.

<< The Non-technology Elements of a Hall Sound System >>

If we list the flow of sound transmission through a hall sound system, we see that the sound system components account for only a portion of the process. Here is the sound transmission path:

  1. A person speaks.
  2. The sound enters the space on stage.
  3. A microphone(s) capture(s) the sound.
  4. A mixer processes the sound.
  5. The sound enters and exits the amplifier.
  6. The sound passes through the loudspeakers.
  7. The sound enters the auditorium's space.
  8. The sound reaches the ears of the listening audience.

From this example we can see that the human and spatial aspects of events and venues are integral to the functioning of a hall sound system; so the sound system design cannot disregard these elements. When a sound system design aims to achieve "fine acoustics" in a hall, the one word "acoustics" refers to all of the many sound-related aspects of the performances and events that will be affected by the sound system, including the human sensibilities of the people on stage and in the audience. Because sound system design includes consideration of how the people in the hall create and hear sound experientially, there will always be ambiguous and imprecise elements to factor into sound system design.

In the pursuit of consistently "fine acoustics," however, the sound system designer's accumulated body of knowledge and information enables him or her to maximize the parts of the sound system design that can be determined based on physical characteristics and the application of technology to factual data. I strongly believe that successful sound system design requires finding the right balance among numerous elements and equipment components. The work involved is not simply a matter of figuring out which manufacturer's brand of equipment is the best or picking the best loudspeaker technology. Rather, for each piece of equipment, there are optimal conditions, equipment combinations, device settings, equipment placement and installation methods, all of which, together, contribute to the equipment's ability to deliver optimal performance.

Therefore, designing a sound system can be compared to building a baseball, soccer or basketball team. It is as important for sound system designers to perceive the potential capabilities and future accomplishments of audio manufacturers and their products, and nurture their use, as it is for ball team owners and coaches to discern which unknown athletes have the potential to be their next stars.

<< Loudspeaker Design Basics >>

Among the components of a sound system design, the loudspeaker design can arguably be considered the most important. The loudspeaker selection and installation design process includes the following considerations regarding the loudspeakers:

  • Objectives of installing the loudspeakers
  • Properties and frequency characteristics of the loudspeakers
  • Number of loudspeaker units and their placement
  • Characteristics of the direct sound from the loudspeakers
  • Affects of sound reflections and sound reverberation on sound from the loudspeakers
  • Appropriateness of the loudspeaker design to the overall frequency characteristics of the space
  • Compensation adjustments and settings
  • Requirements and guidelines for operation and maintenance
  • Fine tuning of the system for adequate sound volume, sound quality and evenly balanced sound distribution
  • Evaluation of successful achievement of "fine acoustics"

This finite list of considerations and decision points is easy to write on paper, but, despite the prevalence of factual engineering tasks involved, there remain many variables—like capturing all of the sound characteristics of musical instruments—that cannot be accurately or completely reduced to measurable values. Until we hear the loudspeakers installed in the hall, there is much that we cannot know.

<< Loudspeakers: Acoustically Important, Visually Problematic >>

Exposed loudspeakers
Exposed loudspeakers

In Japan, architects generally oppose placing loudspeakers in visually exposed locations anywhere near the stage. As a result, pockets for the loudspeakers are typically built into ceilings or walls around the proscenium arch and the loudspeakers are completely embedded into these pockets so that they become hidden from view. Furthermore, most architects' plans call for jersey cloth, expanded metal or some kind of ribbing to cover the face of the loudspeakers so that the audience cannot see any evidence of the loudspeakers at all.

Because of the architects' predisposition to hide loudspeakers, sound system design engineers have difficulty obtaining favorable locations and space volume for loudspeakers. From the perspective of sound system design, we aim to design the loudspeakers' placement to provide direct sound to each and every audience seat. In doing this, we naturally locate the loudspeakers in positions where they can be easily seen by the audience. Meanwhile, the project architects expend their efforts to hide the loudspeakers—which to them are visual hindrances. Also, while the stage lighting equipment sends light from the front side of the audience area towards the stage, the loudspeakers provide sound in the opposite direction, from the stage towards the audience. Consequently, the acoustically desirable loudspeaker placements may interrupt the path of stage lighting to the stage.

Negotiating the location of loudspeakers often requires many meetings and is a topic fraught with tension and competing interests. From time to time, a project's architect will ask, "Aren't there now compact-size high-performance loudspeakers we can use?" In answer to this question, we can only explain that the output of the loudspeaker bears some relation to the size of the equipment and that, for the present, compact-size loudspeakers do not meet the needs of most hall projects. The debates over space for loudspeakers begins during the design phase of projects and continues during the construction phase, where the dimensions of the loudspeakers' pocket openings and the finishing materials around the pocket often need to be revisited and renegotiated.

If a loudspeaker is inserted into a narrow space, certain sound frequencies may become excessively accentuated and exhibit the phenomenon known as boomy sound. This unpleasant phenomenon can be easily simulated by covering one's mouth with a masking material, putting one's head inside a cardboard box and trying to talk. To prevent this phenomenon from occurring with hall loudspeakers, we affix thick sound absorption materials to the walls of the loudspeaker pockets and we remove the loudspeakers' grilles when we install them, replacing them, if necessary, with the thinnest material available. Furthermore, additional approach to improve the naturalness of the loudspeakers' reproduced sound is to use DSP (digital signal processing) equipment and other electronic sound compensation technologies. Nevertheless, performing high quality fine tuning of the loudspeaker system based on the professional's opportunity to listen to the installed equipment is required.

Currently, hall loudspeaker system designs mostly use combinations of different loudspeakers for different bands of frequencies in combination with the multiple loudspeakers units. Narrow columns of line array speakers are also being installed in some newer facilities. The dimensions of openings needed to frame embedded loudspeakers are certain to become even larger than at present. As long as the loudspeakers must be embedded in ceilings and walls, the sound system design will need to increase the area near the hall stage that has sound-absorbing material (inserted in the loudspeaker pockets) which is undesirable condition from a room acoustical view point. In the not too distant future, the architectural design standard of embedding loudspeakers in ceiling and wall pockets may reach its limit and a new design direction may be needed to accommodate the loudspeakers of tomorrow.

* Part 1 of the "Installed Sound Systems" article series appeared in the December, 2005 issue of Nagata Acoustics' News & Opinions.
* Part 2 of the "Installed Sound Systems" article series appeared in the August, 2006 issue of Nagata Acoustics' News & Opinions.

Jean Nouvel and Team Win Paris Concert Hall Design Competition

by Dr. Yasuhisa Toyota

Exterior of the new concert hall (competition design)
Exterior of the new concert hall
(competition design)

Interior of the new concert hall (competition design)
Interior of the new concert hall
(competition design)

Two decades of debate and discussion in France about where and whether to construct a new concert hall has now culminated in the project taking a solid step forward towards realization. A competition begun last year to select the project's architect completed its selection process and awarded the work to the team led by local Parisian architect Jean Nouvel. Mr. Nouvel's winning team includes his firm, Atelier Jean Nouvel, and the New Zealand acoustical firm of Marshall Day in association with Nagata Acoustics.

The project sponsors conducted the design competition for the new hall in two rounds. In the first round of the competition, the selection committee accepted proposals from any architect without restriction. From these submissions, six finalists were invited to compete in a second round for which each team prepared a more detailed design. The six architects and architectural firms invited to participate in the competition's second round were: Jean Novel; Christian de Portzamparc; Francis Soler; Zaha Hadid; MVRDV; and, Coop Himmelb(l)au. On April 5, the French government announced Mr. Nouvel and team's selection.

The French government and the government of the city of Paris are cooperating to jointly fund the project, which will build a new, 2,400-seat concert hall in a complex with other amenities. The target completion and opening dates are in 2012. The hall will occupy a corner of Parc de la Villette (also the location of La Cite de la Musique) in northeast Paris' 19th arrondissement.

Nagata Acoustics will collaborate on the Jean Nouvel team with Marshall Day Acoustics to provide the full range of acoustical design consulting services for the project.


Nagata Acoustics Inc.
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Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
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Los Angeles, CA 90025, U.S.A.
Telephone: (310) 231-7818
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E-mail: info@nagata.co.jp

[ Japanese Version ]