Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 12-06 (No.294)

Issued : June 25, 2012

[ Japanese Version ]

Nagaoka City's New "Ao-re Nagaoka" City Hall and Multipurpose Plaza

By Akira Ono

In Niigata's Nagaoka City, directly across from the JR Nagaoka Train Station, "Ao-re Nagaoka" city hall and multipurpose plaza opened on April 1, 2012. In the same time frame construction completed on the pedestrian bridge that connects the train station to the complex and provides covered access to the complex in inclement weather.

At the center of the new complex is a roofed plaza named Nakadoma, which is architecturally designed to create the atmosphere of an outdoor marketplace complete with a seemingly unpaved walking surface. The complex also has cultural and sports facilities that include an arena designed both for sports and music concerts and a 228-seat municipal civic hall. Last but not least, the complex houses the city council chambers and municipal offices in a location designed to give the city's residents a sense of easy access to their municipal government and its administrative functions.

Nakadoma Plaza takes its conceptual inspiration from traditional Japanese architecture's "doma" (a tamped earth floor found in the kitchen and other portions of "minka" style traditional farmhouses). In addition, in the conceptual programming, the architects compared the plaza to the Roman Forum of ancient times because Ao-re Nagaoka combines a local destination where residents can meet, shop and enjoy sports and music with the municipal seat of government.

The architectural firm of Kengo Kuma & Associates designed Ao-re Nagaoka. A joint venture led by Taisei Construction Corporation built the complex. Nagata Acoustics served as Acoustical Consultant for Nakadoma Plaza, the arena, the city council chambers and the municipal civic hall.

<< Nakadoma Plaza's Acoustics >>

When visitors enter the roofed Nakadoma Plaza, they hear the sounds of people engaging in conversation. The sounds of other peoples' voices can be heard coming from the corners and shadows of the space's complicated geometry. Amidst the bustle and activity of the plaza, visitors can converse easily with their companions, being able to clearly hear the voices of people close by who are speaking to them.

This space has the feel of both a big city plaza and a sequestered lane. In defining the acoustics of Nakadoma Plaza we felt that it would be desirable for people to hear each other with natural sounding acoustics, especially without echoes or reverberations. If visitors' voices sounded as they often do in the tall atriums of some high-rise buildings, this would interfere with their comfort in the space.

To create the natural sounding acoustical environment, at strategic locations we added sound absorbing materials behind the rectangular eaves that form a key element of the interior architectural design. In addition, on the walls and across the entire ceiling we installed thinned wood panels (panels made from wood obtained as part of the process of thinning the timber of a forest). These panels play a large role in helping to diffuse sound in the space.


<< Arena Sound Isolation Design >>

From the start of the arena's conceptual programming, its uses included not only those of a public gymnasium, but also use as a venue for professional basketball games, popular music concerts and other events. We considered all of these uses as we developed the arena's acoustical sound isolation design. In particular, a hotel located adjacent to the arena side of Ao-re Nagaoka raised concerns about sound from the arena disturbing hotel guests. To avert this possibility, sound isolation planning became a major focus of our acoustical design work for the arena portion of the project.

The arena has a concrete structure from ground level to its (highest) third tier seating and above the concrete structure a truss system designed to resist seismic forces and support the room's large roof. Below the truss system we created a sound-isolating ceiling by installing three layers of 15 mm. (0.6 in.) gypsum board that are hung with anti-vibration connectors. In addition, on the expansion parts of the reinforced concrete and the large roof's truss system, we applied pliable sound isolation sheeting. Together, these designs formed our sound isolation strategy.

After the project's completion, we tested the sound isolation implementation by playing music through the arena's sound system at very loud sound levels (90 to 100 dBC). We confirmed that none of the sound generated in the arena could be heard at the adjacent hotel, even when the hotel windows were in an open state.

After Ao-re Nagaoka's opening, the locally based Albirex BB Rabbits professional women's basketball team played a game in the complex's arena. During the first half of the event local children's teams played against each other, followed by the professionals' game. The whole city seemed to turn out enthusiastically for this event that included participation by local residents. The arena plans to schedule more professional basketball games on a regular basis.

City council chambers
City council chambers

<< City Council Chambers' Acoustical Design >>

With the starting point of the Nagaoka City government's policy to be a government close to the people it serves, the project decided to locate the government wing of the complex facing onto Nakadoma Plaza, with the city council chambers separated from the plaza by transparent glass walls that allow people in the plaza a full view of council proceedings. Being able to watch the council in action from the easily accessible Nakadoma Plaza surely does create a feeling of immediate connection to the local government.

Our sound isolation planning for the council chambers aimed primarily to ensure that the bustle and activity in the plaza not disturb the deliberations and proceedings of the council. To this end, we installed double-paned glass. Also, we adjusted the room's architectural interior element of wood panels suspended from the ceiling in an abstract interpretation of Nagaoka City's famous annual fireworks. We discovered that, depending on the angles of these panels, they either provide a desirable sound-diffusing effect or cause sound reflections to propagate from one panel to another, resulting in deleterious echoes. Therefore, we carefully checked the placement, direction and angle of each of these panels.

These city council chambers also have something quite out of the ordinary for this kind of space: a parent-child viewing room complete with double-paned glass between the room and the chambers. Parents and children can watch the legislative proceedings together without worrying about the children's voices disturbing the council's work.

<< Municipal Civic Hall's Acoustical Design >>

This hall has minimalist black surfaces and a simple box shape combined with the same kind of thinned wood panels used elsewhere in the complex. The wood panels form a checkered pattern that decorates the ceiling and some of the walls, repeating a design theme used by the architects in Nakadoma Plaza and the complex's other spaces.

For the acoustical design, we specified that the wood panels be installed at specific angles. Through this design, the panels effectively direct sound reflections from the stage to the audience seating area. The wood panel design also promotes sound diffusion.

<< The Complex's Vibrant First Days >>

Since its opening in April, Ao-re Nagaoka has already hosted numerous events and the complex draws large numbers of residents to Nakadoma Plaza and its other spaces. The city administrative offices have set the goal of providing residents the best service of any city offices in Japan and they are off to a good start by having walk-in office hours that include evenings and Saturdays.

Local residents feel comfortable coming to Ao-re Nagaoka and they show strong attendance and participation in activities taking place in the complex. Ao-re Nagaoka provides an innovative and clearly successful model for publicly funded multi-use facilities.

The home page of the Ao-re Nagaoka website can be found at http://www.city.nagaoka.niigata.jp/ao-re/.

Notes from Attending the Fiscal Year 2011 Technical Stage Professionals Workshop

By Makoto Ino

Recently, I took a 2.5 hour flight from Tokyo to Okinawa Prefecture's Naha Airport and then drove for 30 minutes southeast across the island until I arrived at the sparkling blue waters of the Philippine Sea and the coastal Nanjo City's cultural center named Sugar Hall. Sugarcane fields fill the surrounding landscape and at the center's service entrance children can be seen playing in the sun. The picturesque atmosphere had a welcome sense of calm after a day of travel.

For the three days beginning on March 7, 2012, some 80 technical stage professionals gathered here to participate in the Fiscal Year 2011 Japan Technical Stage Professionals Workshop. The Japan Agency for Cultural Affairs and the Association of Public Theaters and Halls in Japan sponsored the event. I participated in the workshop together with about 50 or more other instructors and event personnel.

This contemporary Kumi-odori musical dance performance was produced during the workshop as a hands-on way to learn the practical steps involved in staging a production.
This contemporary "Kumi-odori"
musical dance performance was produced
during the workshop as a hands-on way
to learn the practical steps
involved in staging a production.

The association's executive director, Mr. Tatsuaki Matsumoto, spoke at the beginning of the event and explained that the 20 workshops held in the past each targeted one specific technical area, such as stagecraft, lighting or sound. This time, the association began a new approach to the workshop event that broadens its scope. The gathering in Okinawa represents the first event of this type and included technical professionals from the areas of both lighting and sound. One result of the expanded scope was the rather large number of instructors and event personnel involved in this year's event.

The executive director of Okinawa's Chatan Nirai Center, Mr. Ikuyoshi Kon, delivered the workshop's opening remarks. During this talk, he told the attendees to remember to obtain the workshop completion certificate now being offered by the association after this kind of gathering. The issuing of this kind of certificate is related to the national government's efforts to develop the legal foundations under which theatres and concert halls operate in Japan.

In 2001, the Japanese Diet enacted the Basic Act for the Promotion of Culture and the Arts, and in February, 2011, the "Outline of the 3rd Basic Policy on the Promotion of Culture and the Arts" was issued. One of the Outline's three sections establishes six priority strategies for "building a Nation based on Culture and the Arts". One of these strategies specifically addresses "enhancing the human resources who create and support the arts". Compared with the narrow focus of workshops held by one or another specific professional organization for one technical profession, at the cross-functional workshop held in Okinawa I had the strong feeling that this event was well aligned with the goals of promoting culture and the arts as defined in the national legislation and by the Japan Agency for Cultural Affairs.

The workshop in Okinawa used the phrase "Increase your knowledge and polish your skills!" in advertisements promoting the event. As this line of copy suggested, the workshop provided two kinds of sessions. There were sessions targeting the professionals' understanding of their fields so that they can be more creative and effective in their chosen specialties at theaters and concert halls. There were also sessions that focused on knowledge and skills that would be directly applicable by the attendees in their daily work. To stage any arts performance requires a diverse and substantial range of knowledge and skill, including being able to communicate among techncial professionals with different specialties and understanding the preparatory and operational predecessors, dependencies and necessary sequencing of activities for staging the production. The workshop program aimed to teach this entire process as well as the communciation skills of staging a production.

The first special guest speaker on the program was the veteran stage lighting professional and stage consultant Mr. Sumio Yoshii, who spoke on the topic of "The Essential Aspects of the Technical Stage Role and Stage Production". At the outset of his talk, Mr. Yoshii immediately shared his main point that people in technical stage professions must understand that they are serving the arts while also contributing to the creativity of a production. To this end, the professionals add to their knowledge of their stage and production crafts and professions and, most importantly, they must bring a true love of the arts to their work. For Mr. Yoshii, it is essential that every person who works in a hall or is involved with a stage production should have a mental attitude that finds delight in doing work that puts the person in direct contact with producing the performing arts.

Former University of the Ryukyus Prof. Toru Nakamura delivered the next session on the topic of "Creative Use of Stages Across Venue "Borders". In this talk, he presented examples of novel and multifaceted ways to use concert hall venues. His presentation included a mini-concert. The next address was by Mr. Hideo Shimokawa of the Institute of Electrical Installation Engineers of Japan. Mr. Shimokawa spoke about the state of energy conservation in Japan.

A sound designer, lighting designer and scriptwriter-director communicate in front of an audience about the kumi-odori dance production.
A sound designer, lighting designer
and scriptwriter-director
communicate in front of an audience
about the Kumi-odori dance production.

After Mr. Shimokawa's talk, the remainder of the program was devoted to stagecraft and production-related topics. A team that included a scriptwriter-director, a lighting designer and a sound designer jointly led the program entitled "The Commonalities and Co-ownership of Staging a Theatre Production". During this program, the presenters covered everything from the basics of on-site work done by sound and lighting technicians through every step of producing a contemporary "Kumi-odori" musical dance performance. While going about the tasks needed to stage and produce this performance for the attendees, the instructor team explained their work and how they interact with each other at each step of the process. The instructors showed a palpable and ardent determination to share their knowledge of every detail of production that happens "behind stage" in order for a performance to be produced.

A concert with a sanshin traditional Okinawan string instruments, a guitar and a vocalist was staged outdoors.
A concert with a "sanshin"
traditional Okinawan string instruments,
a guitar and a vocalist was staged outdoors.

Another similar program took place outside, ignoring the light rain. During the preparations and production of this performance of a traditional Okinawan "sanshin" instrument, a guitar and a vocalist of traditional "shima-uta", the workshop participants gained insight into creating the stage set, conducting a rehearsal and producing the actual performance. The instructors' detailed presentations included how to use moving stage spotlights and the most recent sound system equipment.

The last topic on the workshop's program was "An Introduction to Safety Standards for Stage Technicians". Using guidelines published by the Japan Council of Performers' Organizations as its outline, this session engaged the workshop's instructors in a discussion about the dangers inherent in working on-site at a theatre or hall. The seminar's participants emphasized the importance of implementing and following safety standards.

After three days filled with instruction and presentations, the workshop concluded with both instructors and attendees well satisfied with the event. The organizers plan to hold similar cross-functional workshops in the future. The technical professions required to stage and produce the performing arts span a diverse range of specialties. This workshop confirmed that the more we know about each other's roles and workflows, the better we will be able to work together. Moreover, this will benefit and improve the overall quality of the performing arts in Japan.

My Retrospective on Building 1/10 Acoustical Scale Models - Part 4:

Working Knee-deep in Snow in an Abandoned School Building (Harmony Hall Fukui, 12/1994 - 4/1995)

By Nobuyuki Ebihara

<< General Space Requirements for a 1/10 Acoustical Scale Model's Site >>

It seems that it is never easy to find the right location for the construction of a concert hall's 1/10 acoustical scale model. This is because of the requirements and constraints a location must satisfy for it to be considered. The first requirement, of course, is the site's total area. A 1/10 acoustical scale model needs a large space. For example, the model of a 2,000-seat hall requires a space with at least 20 Japanese "tsubo" (66 sq. m. or 710 sq. ft).

The area needed for a 1/10 acoustical scale model includes both space for the footprint of the model and an essential perimeter area surrounding the entire model where acoustical consultants can prepare the tests that will be done in the interior of the model and from where they can observe activities happening inside the model. The site also needs "operational" space for electrical and sound equipment used during the acoustical tests. For these reasons, I quote 20 Japanese "tsubo" as the minimum area required of any site proposed for a concert hall's 1/10 acoustical scale model.

For a variety of reasons, I build the 1/10 acoustical scale model indoors. Therefore, the next requirement for the model's site concerns the ceiling height of the location. The height of 1/10 acoustical scale models vary from hall to hall, with taller models having heights of as much as 2.5 m. (8 ft). In addition, the acoustical testing activities that will be done in the model require that the entire model be built on a raised frame, which adds another meter (3 ft) to the model's overall height. There must also be sufficient space above the model, both so that I can build it. The total height needed can be estimated at 4.5 m. (15 ft).

To summarize, the 1/10 acoustical scale model needs to be built in an indoor location with dimensions measuring at least 66 m. sq. x 4.5 m high (710 sq. ft x 15 ft). The indoor site should have a rigid floor so that the model can be made level and, in addition, sites with loud ambient noise levels need to be avoided. When possible, it's desirable to build the model near the site where the concert hall will be constructed, but finding a suitable nearby site rarely happens.

<< Building Harmony Hall's 1/10 Acoustical Scale Model in the Snow Country of Fukui Prefecture >>

Inside view of the model Harmony Hall Fukui
Inside view of the model Harmony Hall Fukui

I built Harmony Hall's 1/10 acoustical scale model in a mountain village named Imadate. After traveling to the Japan Railway's regional Fukui Station hub and then two stops west on a local train to Takefu Station, the car ride to Imadate took about another 40 minutes. The first time I went to Imadate, one of the project's local personnel drove me to the village. When we arrived at the site where I was to build the model, I could not believe my eyes. The site's building was an old wood structure that in its better years served as a school. The building must have been built decades earlier in the mid-1920s and it still had the original "nankin shitami" style of wood siding that was popular at the time. ("Nankin shitami" is a style of exterior wall covering made with long, flat pieces of wood attached horizontally so that the bottom of one piece overlaps with the edge of the wood piece below it.)

Inside, the school building had a ground floor with a large auditorium measuring some 198 sq. m. (2,131 sq. ft) and a second floor divided into several smaller rooms that must have been used as classrooms, with each school year assigned to a different room. These rooms had weathered and cracked blackboards that clearly had ended their usefulness many years earlier and now exhibited a color more distinctly sepia than black. Outside the building, an Asian "ascending" kiln had been built into the steeply sloped hill that rose next to the school building. Local pottery enthusiasts seemed to be using the school building as a ceramics workshop.

I made a partition in the ground floor's auditorium that gave me about 1/3 of the auditorium's total area and in this space I built Harmony Hall's 1/10 acoustical scale model. By the time the nearly 3 tons of partially assembled sections and parts arrived and I laid them out in the order needed for the model's construction, they filled the entire allotted floor space. The prefecture's on-site project representative looked at all of the parts and pieces and, with a mixture of wonder and delight, exclaimed "How will you get all of these separate and complicated things to fit together in one model?"

By this time, I already had experience building 1/10 acoustical scale models, so at this juncture in the Harmony Hall project, I had no worries about the work ahead of me. Little did I realize that Jack Frost would come and interfere with my work plans. I brought a large kerosene stove to the site, but on days without a ray of sunlight the stove was no match at all for the cold. The cold made my hands numb. If I wore heavy clothing I could not move freely inside the model, so I constantly felt like my whole body was frozen to the bones. On mornings after a night of snowfall, I would find a meter or more of snow piled up around my car. Unless I began my day by shoveling the snow from around my car and, after driving to the school, shoveling again at the school entrance, I could not get into my car or the school. Also, the road I travelled to get to the school rose rather steeply and, more than once or twice, my car slipped into a tail-spin that left me facing 180 degrees in the wrong direction. I sometimes had the feeling that instead of building an acoustical scale model, I was carrying on a fight against snow and cold.

Nevertheless, at the end of each day, when I returned to my lodging feeling cold and soaked and thinking that I looked like a drowned rat, the owner of the inn unfailingly greeted me with a warm smile and she always kept the temperature in the inn warm for my return. At the local "izakaya" pub, the owner would greet me with a comment about the hard day I must have had and he served me delicious local specialties that I would not even have known to order. In addition, I must mention Mr. Matabei Minowa, who lived not far from the school building and served as the caretaker. I owe him a debt of gratitude.

I was totally new to the challenging physical elements of Fukui Prefecture and the difficulties I encountered with the weather could easily have discouraged me and caused me to lose heart. Instead, these and other local people bolstered my spirits and it is thanks to their support that I was able to persevere and see the project through to completion. This 1/10 acoustical scale model came into being while being frozen by the bitter cold and warmed by the caring hearts of the local townspeople. I've heard that if an old tree is felled in the middle of the winter and slid through the snow until it reaches a violin maker, nothing quite matches the exquisite tones of the instrument crafted from this wood. Harmony Hall is like such a violin, and its beautiful acoustics deserve to endure and be enjoyed for many generations to come.

For me, the Harmony Hall 1/10 acoustical scale model project proved to be an unexpectedly long and arduous expedition. During the project, on return trips to Tokyo from Imadate, I traveled through tunnel after tunnel along the Japan Sea coast. In-between the tunnels' periods of darkness, the brilliant blue of the Japan Sea would suddenly fill my vision, sometimes shining as brightly as a blue flame. Now this memory, too, fills me with nostalgia for the human warmth and kindnesses that gave me strength in the cold Fukui winter.

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 ]