Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 12-12 (No.300)

Issued : December 25, 2012

[ Japanese Version ]

Nagata Acoustics Publishes the 300th Monthly Issue of Our Newsletter
--From the Beginnings of Nagata Acoustics' Monthly Newsletter to Today

By Dr. Minoru Nagata, Founder and Executive Advisor

The first page of the first issue of Nagata Acoustics' Newsletter, published in January, 1988.
The first page of the first issue of Nagata Acoustics'
Newsletter, published in January, 1988.

I founded Nagata Acoustics in 1971. The timing was fortuitous because Japan was entering a period of rapid growth and I received a sufficient number of requests for acoustical room designs, acoustical environment evaluations and other work to put my new company on a solid footing. However, during that period, the number of publicly funded cultural facilities in Tokyo remained few, while the rapid economic growth produced the unfortunate side effect of noise problems in many parts of the city.

In October, 1986, with the opening of Suntory Hall, I decided that it was time to promote greater understanding and recognition of acoustical design, so I began the monthly publication of Nagata Acoustics' newsletter for this purpose. I gave the newsletter the tag line "Quietness, Comfortable Sound, Excellent Acoustics", and in January, 1988, I published the first issue of the newsletter.

The December, 2012 issue is the 300th issue of the newsletter. For 25 years we have reported on our acoustical design activities and related topics. Of course, the mainstay of our articles has been the approximately 300 hall projects built in Japan and around the world to which Nagata Acoustics contributed acoustical design expertise. In addition, the related topics of the newsletter have included information of interest to our readers engaged in managing halls and hall projects, book and concert reviews, announcements about upcoming performances, first-hand reports of acoustical society meetings, perspectives on events held by audio system manufacturers and other industry gatherings, and introductions to exciting new technologies and products, as well as other topics.

Even before I began publishing the Nagata Acoustics newsletter, my company had completed more than 50 hall projects. We designed these early halls during the heyday of multipurpose hall construction and, therefore, we designed these halls' acoustics to suit a variety of performance genres while always pushing the envelope to achieve concert hall-quality acoustical environments.

During this time we were already creating designs that promoted lateral reflections and our hall projects included room acoustical designs that incorporated pipe organs, variable reverberation time functionality and anti-vibration and noise mitigation strategies for nearby underground train lines, plus other advances in acoustical design techniques and technologies. I would like to find the opportunity to write a series of articles for this newsletter about the halls still in use today that were built during the early years of Nagata Acoustics.

<< Progress in the Field of Room Acoustics >>

In the early 1970s, a client came to Nagata Acoustics with the request that we work on a renovation of an existing hall to reduce the reverberation time. Similarly, around the same time frame, after one of our concert halls completed, a number of piano instructors complained that they could not perform in the hall because of its long reverberation time. Recently, I was in Okinawa and saw a church built in the early post World War II era that, incredibly, has sound-absorbing materials installed across its entire ceiling and walls.

By comparison, in a small new hall recently completed in a Tokyo suburb, every aspect of the hall's interior, from the shape of the ceiling to the sound diffusing elements incorporated into the design of the side walls, as well as the sound absorbing design of the back wall aim to maximize the concert hall-like acoustics of this multipurpose hall, regardless of the fact that the hall's ceiling height could not be made as high as would have been desired for a true specialty concert hall. When I visited this new hall, I could see that its design captures the essence of what makes a classical music concert hall a classical music concert hall.

<< Progress in Anti-vibration and Sound Isolation Design >>

Hall heating, ventilation and air conditioning systems ("HVAC") are a main source of noise in halls. In the 1960s, we used NC-25 as our standard target level of quiet for concert halls. Today, for most of the halls we design we achieve quietness levels below NC-20.

For hall projects built in urban areas, underground train systems are the primary cause of vibrations. Nowadays, to prevent train vibrations from transferring to the hall, we typically adopt an anti-vibration "floating" structural system for the entire hall.

Clients also often request sound isolation strategies that make possible the simultaneous use of adjoining and nearby rooms and halls. In the early years of Nagata Acoustics, we worked hard to achieve sound isolation of 65 to 70 dB (at 500 Hz) between a hall and nearby rehearsal or practice rooms. Today, we consider sound isolation of 80 dB as a design goal and we have also successfully achieved sound isolation in excess of 90 dB.

<< Challenging Topics of Today >>

After more than four decades, our motto remains "Quietness, Comfortable Sound, Excellent Acoustics". Above, I wrote in broad brush strokes about some of the architectural acoustical design advances for halls that we've been privileged to participate in designing and implementing during these 40-plus years.

Today, new trends provide new challenges. Some of the sources of our new challenges include the increasing diversity of performance genres and crossovers among genres, as well as the increasingly free-form and unique architectural designs of contemporary architects. To find the best solutions for these new challenges, we will need to apply both our best efforts and our expertise. We look forward to partnering with clients and other experts to build the new halls of the future.

--Evolving for the Future

By Satoru Ikeda, President

From the earliest days after Nagata Acoustics' founding through the present time, clients, architects and others have continued to request our participation in a many projects that enable us to use our acoustical engineering skills and further grow our expertise. Concert halls, multipurpose halls, theatres and auditoriums have comprised about 50% of our work, and the other 50% of our work has been for educational institutions, sports facilities, conference centers, houses of worship, legislative chambers, exhibition halls, residences and even funeral homes.

<< Dedication to Each and Every Project and to Growing our Competency >>

Whether we are working on one of the world's most architecturally and technically cutting edge projects or a project for a specific individual or a group of people, we always dedicate ourselves completely to achieving the goals we and our clients set for our work. In the early years of our company, the field of architectural acoustics was still coming into its own technologically. I remember that we spent much time and effort promoting the importance of including a professional acoustical consultant from the earliest planning phases of a project.

In the beginning, some project stakeholders may have thought that our science still had ambiguities or we may have seemed too zealous about our role, but it was by persevering together with our clients and other project participants that we could now deliver excellent acoustics, from sound isolation to acoustical room design to sound system design. When project needs are solved, new technological understandings achieved and projects completed successfully, we become invigorated for the challenges of our next projects.

<< Acoustics in Living Environments >>

One area of architecture that still awaits the benefits of acoustical design is buildings for the living environment. Many architects and clients now focus effort on the overall pleasantness of the environments, including its acoustics, and interest in this area continues to grow. However, attention to the importance of the acoustics in general buildings tends to still be an afterthought and we cannot yet say that we designed the spaces so that they have the most desirable possible acoustical characteristics.

People now take as a given that halls, studios and other performance spaces require the most technologically advanced room acoustical designs, sound isolation designs and noise control. Many acoustical problems that need to be solved appear in the design process of these facilities. Our clients and project partners also expect us to continue to improve our knowledge and our implementation technologies. However, when we think of other kinds of public spaces and the three goals of "Quietness, Comfortable Sound, Excellent Acoustics", it seems that the focus on these objectives diminishes, despite the fact that acoustical problems occur in these facilities in like manner.

Of course, safety and security always deserve the highest priority, but our ambient acoustical environments also deserve attention as well. Surely, general building design and construction projects now routinely incorporate some aspects of acoustical design, especially sound isolation technologies and mitigation of HVAC and other equipment noise, but I believe that the industry needs to adopt additional architectural acoustical designs and techniques in order to achieve the right balance between the importance of our acoustical environments and other needs.

<< Architectural Acoustics for Schools >>

In particular, I would like to see more attention given to the acoustical characteristics of indoor spaces in school buildings. At the most fundamental level, teachers need an acoustical environment where they can talk to students easily, without straining their voices or encountering undesirable acoustical phenomena, and students from young children to teenagers need to be able to hear what their teachers are saying, and have the questions they ask and answer be audible.

After the Great Tohoku Earthquake of 2011, temporary classrooms were set up in sectioned off areas of the gymnasiums where people had taken refuge. A newspaper article entitled "The Sound Ruler" described how students in these temporary classrooms managed to control their voice levels so as not to disrupt the others. The article explained that the students had taken quietness in classroom environments for granted and that, in their temporary, noisier environment they devised a five level measure of their voices to adjust the loudness.

Perhaps the children at the earthquake relief locations were especially sensitive to their changed sound environment, but I think that the concern arises not only in disaster situations but even under normal circumstances. Also, school gymnasiums in Japan often double as auditoriums as well as being places for emergency evacuations, yet the quietness and acoustical environment of school gymnasiums is typically not given sufficient thought when the gyms are designed.

If a school is located near a public hall or cultural center with a hall, the school may be able to use the nearby facility for students' music appreciation clubs and student music recitals and performances, but if there is no such facility nearby, then the gymnasium becomes the default venue for these kinds of activities. I think it most unfortunate for the developing susceptible youths, that the venue for performances and appreciation of music is relegated to gymnasiums which are totally unsuited for the purposes. Though it is not about the safety and security dogma, but it is too late when it falls apart. When it comes to the topic, it seems that many non-technical issues underlie and is very frustrating that us acoustical consultants do not have much opportunity to utilize expertise and practical experience for solving the problems.

<< Looking towards Nagata Acoustics Future >>

At Nagata Acoustics, we will continue to increase and pursue mastery of acoustical design of concert halls and other performance spaces. At the same time, we hope to broaden the application of acoustics to everyday spaces, because great benefit can be obtained from improving the acoustics of these spaces.

The projects of today and the future require that we work with clarity of purpose, applying the knowledge and expertise we already have and wisely evaluating and incorporating new advances in methods and technology. This approach is at the core of Dr. Nagata's guiding leadership. We start by directly listening to the acoustics of spaces, refine our ability to hear the acoustics of spaces and advance the practical application of acoustical engineering by devising innovative ways to solve the needs of projects, be they halls or other spaces.

Potpourri Hall Opens near Tsurukawa Station, Machida City

By Ayako Hakozaki

Building Exterior
Building Exterior

This autumn, a new cultural center opened its doors at a site across from the Odakyu Train Line's Tsurukawa Station in Machida City, a suburb west of central Tokyo. Wako University, a local private college, earned the naming rights to the facility by its funding of the center through the year 2022, and the school chose the name Wako University Potpourri Hall Tsurukawa for the center. In addition to "potpourri" having the meaning of a sachet made of a mixture of dried flowers, the etymology of the potpourri is Latin "populous", meaning "government of the people". The university included "Potpourri" in the building's name to emphasize its vision of a facility that has a fresh and inviting "aroma" where people like to spend time, meet with friends, converse and take part in activities.

Because the facility's name includes "Wako University", some stakeholders raised a concern that confusion might arise over whether the building belongs to the private university or is a public facility. To mitigate this possibility, for the first six months after the building's opening the name "Machida City Cultural Center" will also be displayed on the facility's façade and in other places where the facility's name appears.

The architectural firm Environment Design Institute designed the building. Tokyu Construction served as the general contractor. Nagata Acoustics provided the acoustical design and sound isolation design consulting services.

<< Architectural Overview of Wako University Potpourri Hall Facilities >>

North side atrium -a view of the café seen from the library
North side atrium
- a view of the café seen from the library
South side atrium -a view of the community space seen from the 3rd floor
South side atrium
- a view of the community space seen from the 3rd floor

The new facility serves three main functions. It provides a multipurpose hall, a library and a community space. For the project's 2008 design competition, the winning design proposal included the concept of "crossing over" as an overarching design principle. The building's design aims to connect Tsurukawa's natural environment with the people who use the facility and with the activities that take place there.

To implement the design principles and aims, the design team considered ways to create connections between individuals and groups of people engaged in different activities throughout the building. The methodology the design team adopted uses fluid lines and visual connections across the zones to create the sense of cross-zone connectedness.

Upon entering the building, visitors come into the building's center core, which has bookcases built into the walls that surround it. At the north and south sides of the core area, two atriums extend upward. The north side has a café and an open area "salon" where people can sit or meet casually. The architectural design features a glass façade and white walls that give this space an airy and bright atmosphere.

In the north atrium, taking the stairs up to the second floor brings visitors to the library. The library has its own café atmosphere, so that when visitors happen to come to this floor and find themselves in the library, they will want to choose a book and spend some time in this welcoming space.

The stairs of the south side atrium take visitors from the ground level up to a glass-enclosed mezzanine. Community space provides space for people to congregate casually. Also, the stairs connects to the library of the north side. Another set of stairs on the first floor of the south side atrium takes visitors to the building's basement level where the hall and studios are located.

The building has a third, top floor. This floor has a rehearsal room, a multipurpose room for small concerts, lectures and exhibitions, and an exercise room. These spaces are available for rent on a partial or full-day basis.

<< Sound Isolation Design for the Entire Facility >>

Cross-sectional view of building and rooms with sound isolation treatments
Cross-sectional view of building and rooms with sound isolation treatments

Potpourri Hall Tsurukawa is located next to train tracks of the Odakyu Train Line. The hall and several other spaces require a quiet ambient environment and the nearby train lines generate undesirable vibrations. Therefore, we implemented a sound isolation strategy to mitigate the transfer of vibrations from the train lines to the spaces in the building that require a quiet environment.

In addition, because the building is a multipurpose facility, our design provided for sufficient sound isolation between and among the various rooms and areas used for different purposes. To this end, we adopted anti-vibration and noise isolating structural designs for the hall and studios on the basement level, as well as for the multipurpose and rehearsal rooms on the third floor.

The space immediately above the hall serves as the entrance lobby for the entire facility. We anticipated that this space will have a lot of foot traffic. To mitigate the transfer of impact noise from the foot traffic to the hall below, we collaborated with Institute of technology of Tokyu Construction to measure the sound isolating performance of several flooring solutions in the laboratory during the construction phase of the project. Eventually, we selected rubberized sheeting with an additional under-layer of cushioning material. The resulting performance obtained excellent sound isolation that prevents the transfer of noise and vibration from the bustling lobby entrance to the hall. We achieved an appropriate level of quietness in the hall.

The Hall
The Hall

The hall's extra-wide aisle seats for parents with little children
The hall's extra-wide aisle seats
for parents with little children

<< The Hall >>

The facility's hall, located on the basement level, is a small size hall that accommodates 300 people. In this hall, we were constrained to a lower than optimal ceiling height because of the hall's basement level location. Nevertheless, we designed the hall's configuration and acoustical room design to make the hall's acoustics suitable for live, non-amplified concerts.

In small concert halls, the presence of effective sound diffusing elements in the interior design takes on increased importance. In this hall, we implemented a wall design that created multiple angles along the walls and we added a surface treatment of ceramic tiles to promote sound diffusion.

One somewhat unique feature of this hall is its extra-wide aisle seats. Machida City requested these custom seats in order to provide comfortable seating for parents who are accompanied by small children. However, these seats are not reserved exclusively for adults accompanied by small children, so adult patrons may also use these seats. When hall patrons sit in the extra-wide seats they will likely think they've been treated to a special perk.

<< The Hall Opening Concert Series >>

Potpourri Hall Tsurukawa held its grand opening on October 17, 2012. For the hall's inaugural concert, violinist Mariko Senju gave a recital performance. Ms. Senju played a wide range of pieces from Albinoni's Adagio to Brahms's Violin Sonata, giving expression to the broad range of tone colors of her Stradivarius.

In between compositions, Ms. Senju spoke briefly to the audience, asking them to listen to how her violin's tone colors sound in the new hall. I was impressed with Ms. Senju's ability to inspire the audience's interest in the hall's acoustics.

After the concert, I asked Ms. Senju to share with me her impressions of the new hall. She told me that because the hall is not overly lively, a very wide dynamic range of compositions, from quiet works to powerful ones, can be played in the hall.

The inaugural concert series will continue into next year with a calendar of diverse performances that includes chamber music, piano recitals, Japanese yose storytelling and popular music concerts. I hope that some of our readers will be able to pay a visit to this new hall and enjoy its atmosphere and fine acoustics.

The Wako University Potpourri Tsurukawa web site (available only in Japanese) can be found at

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 ]