Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 07-08 (No.236)

Issued : August 25, 2007

[ Japanese Version ]

"Closed-while-Open Space" at Tokyo College of Music's New Centennial Hall Building

by Ayako Hakozaki

This past spring, Nagata Acoustics saw the completion and opening of several projects that added new buildings on music college and conservatory campuses. In April, this newsletter introduced readers to our acoustical consulting work for Showa University of Music's new campus building. In this article, I will focus on the newly completed Centennial Hall Building for Tokyo College of Music.

<< Client and Project Background >>


4th Floor Layout
4th Floor Layout

The Tokyo College of Music ("Tokyo Ondai") campus is a 15-minute walk from Tokyo's Ikebukuro Station. But compared to Ikebukuro's frenzied commercial district, with its stores, eateries, flashing billboards and a large hub train station, Tokyo Ondai's Zoshigaya neighborhood presents a picture of tranquility.

Tokyo Ondai began in 1907 as the Toyo Conservatory of Music, making it Japan's oldest private music college. Originally located in the Sarugakucho section of Tokyo's Chiyoda City, the school lost this building in the 1924 Great Kanto Earthquake and relocated to its present campus the following year.

The Tokyo Ondai Centennial Hall Building project completed this spring was to reconstruct the main building on the Zoshigaya campus and was timed to commemorate the college's 100th anniversary. Kume Sekkei designed the building, Yasui Architects & Engineers were responsible for the design engineering management and Toda Construction served as the general contractor.

<< Overview of the "Closed-while-Open" Facility >>

The new structure includes the Centennial Hall, one large and one medium-size classroom that can double as small, chamber concert spaces, classrooms, studios and suites of practice rooms on the basement level and the uppermost fourth floor.

In Kume Sekkei's submission to the competition for this project, Kume's architect, Mr. Noguchi proposed a "closed-while-open" concept, a seeming oxymoron, yet a phrase that aptly describes the distinctive theme of the building's design. Set in tranquil residential surroundings, the building houses a concert hall and numerous classrooms and practice rooms where musicians must be able to practice and play in sound-isolating environments, free of any concerns about their music bothering someone in another room —or outside— the building. In other words, the requirement was to "close in" (isolate) sound.

Typically, the requirement to "close in" sound results in rooms and spaces that look and feel confined. For Tokyo Ondai's Centennial Hall Building, the hall and classroom wings are connected by a core galleria with skylights that bring natural light into the building. The rooms surrounding this core use glass walls abundantly to create the visually open feeling that makes the building "closed-while-open."

The distinctiveness of the building's architecture resides in the creative juxtaposition of rooms and glass walls to achieve "closed-while-open" spaces. The galleria atrium rises through all five above-ground floors and each floor's rooms are arranged in three-dimensional space along the gently graded core stairway and corridors for a dynamic-looking layout. Glass panels enliven stairway and corridor walls with ever-changing views of the activity taking place in adjacent rooms. In addition, the fourth-floor suites of practice rooms are built on bridges across the galleria, so that while each practice room may have limited space, they each have a view into the galleria atrium, creating a feeling of openness in each room. The "open" aspects of the galleria design give the entire building an energetic atmosphere and create the very attractive sense that the creativity in one space stimulates the creativity in other rooms.

<< The Acoustical Design of Centennial Hall >>

Interior of Centennial Hall
Interior of Centennial Hall

Centennial Hall has a seat count of 806 and an orthodox shoebox configuration. The two side balconies protrude into the space above each side of the stage and the two levels of eaves on the stage's real wall connected to the balconies serve as sound reflective surfaces to provide both the stage and the audience seating with rich sound reflections. The surfaces of the hall's sidewalls with accordion-style pleating were designed to effectively create sound reflections to the main audience seating area. Using this design, one side of each "pleat" faces towards the stage and the other side faces toward the rear of the hall. For the sides of the "pleats" that face the stage, precast concrete panels were used to ensure robust sound reflections across the entire sound spectrum, including low frequency sounds. In the sides of the "pleats" facing to the rear of the hall, glass panels were fitted. When the hall is not being used for a performance, the glass panels allow natural light to flow into the hall, and electric light-blocking curtains that can be hung behind the glass panels were installed to darken the hall during performances.

On the ceiling above the main seating area of the hall we installed gently curved reflection panels, each set at a slightly different angle, in order to provide equally balanced sound reverberations to all seats in the audience. For the floor of the audience seating area we chose wooden flooring on wood framing to feel weighty sound, and for the stage floor, we used planks of laminated Japanese cypress. At the request of the school's piano professor, we embedded small markings on the stage floor that indicate the location of the stage floor's support framing, so that the piano can be placed on stage taking into consideration the location of the supports beneath the stage.

Our design of the reverberation characteristic of Centennial Hall required that the hall be able to adapt to a range of performance types, and to practice as well as performance situations. Included in the planned uses of the hall will be instruction of musical classes with a few audience presented, for which the reverberation time needs to be controlled. To enable the hall to be adjusted to meet the reverberation needs of different types of performances, deployable sound-absorbing curtains were installed between the side balconies.

For sound isolation, we relied primarily on the hall's location being separated from the other rooms of the structure by the galleria and its atrium. Some sections of fourth-floor practice rooms are located adjacent to the hall and for these rooms we used highly effective anti-vibration and sound isolating structural designs to achieve a high level of sound isolation performance between them and the hall.

<< The Large and Medium-sized Classrooms >>

The large and medium-sized classrooms are constructed parallel to the galleria stairway and have a stepped floor and stepped seating for 150 to 200 persons. Conceptually, these two spaces are intended to be able to double as both classrooms and mini-concert halls.

In small rooms, sound reflections tend to become concentrated in an early time frame, reaching the audience precipitously and dissipating quickly. In these two rooms, we increased the delay of the sound reflections to obtain rich acoustics despite the relatively small size of the rooms. We angled the sidewalls and the upper portions of the front and rear walls outwards and gave them sound-diffusing surfaces.

Our design for these rooms also focused on achieving high performance sound isolation levels between each of these rooms and nearby spaces. Specifically, we adopted vibration and sound-isolation structural designs that incorporate elasticized floating floors. Because glass is extensively used in both the internal walls of these rooms with floating sound-isolation-structures, and in the walls of the fixed sound-isolation building elements adjacent to them, we made sure to provide sufficient air space between the sound isolation layers. We also incorporated sound absorbing elements in the interior design of the air space. As a result of these sound-isolation strategies, we achieved measurements greater than D-80 as the sound isolation performance level between these rooms and adjacent spaces.

<< The Suites of Practice Rooms >>

A music college needs many rooms where students can practice their instruments individually. The Centennial Hall building has 24 practice rooms on the basement level and 33 practice rooms on the fourth floor. We placed the practice rooms for large-sound-volume instruments —such as percussion and brass wind instruments— in the basement, the location farthest away from Centennial Hall and from the classrooms, so that the chance of these instruments' practice sounds transferring to the halls could be most surely averted. We likewise reserved the fourth floor practice rooms for string and woodwind instrument practice, because the sounds these instruments produce are comparatively less loud.

For all of the practice rooms, we specified vibration and sound isolation structural designs with glass-wool floating sub-floors. We finished the practice room walls with sound reflective treatments and provided sound absorbing curtains that the room occupant can deploy and adjust to add or decrease a room's reverberation characteristic.

I wish to extend my heartfelt wishes that this new Centennial Hall Building will continue to be full of the vitality and creativity so apparent already in its architectural design and in the students who fill it today.

Tokyo Ondai's URL is http://www.tokyo-ondai.ac.jp/en/index.html.

AOSSA Building Opens in Fukui Pref.'s Teyose Redevelopment District

by Akira Ono

Exterior of AOSSA
Exterior of AOSSA

As part of the expansion of Japan's bullet train line system, preparations are underway for the construction of the line to the Hokuriku area that hugs the Japan Sea coastline. The Hokuriku bullet train line will complete in 2014. Prior to the construction of its tracks, stations along the route are being upgraded and rebuilt. One of these stations is the Japan Railroad's Fukui Station in Fukui City. The rebuilt station design connects the neighborhoods to the east and west of the station, so that the Teyose District, on the east side, no longer has the image of being the rear side of the station. Instead, this district is the focus of a redevelopment completed in April 2007. The new complex is named AOSSA, based on the Japanese word "aimasyou," which means "let's get together." The AOSSA spelling matches the word's pronunciation in the local Fukui dialect.

<< Overview of AOSSA >>

The first three floors of AOSSA provide rental space for shops and other commercial businesses; floors four through six house offices and facilities run by Fukui City, and the top two floors (floors seven and eight) have facilities funded by Fukui Prefecture. AOSSA's combination of tenants and landlords represents an example of the public and private sector working together to realize a redevelopment effort.

The city's floors feature a library and human services facilities in a section of the building called "The Regional Exchange Plaza." On the seventh floor, Fukui Prefecture put a Broadcasting College and rooms for various community activities. On the eighth floor, the prefecture built a new Prefectural Public Hall. The hall is designed as a multipurpose auditorium with portable seating and a proscenium stage. The new hall accommodates a maximum of 535 seats and is a replacement facility for the previously existing Fukui Public Hall, an outdated and worn structure that had a maximum capacity of 636 seats. With AOSSA's completion, the old hall's operations moved into the new facility on AOSSA's eighth floor.

The architectural firm of MHS Planners, Architects & Engineers designed AOSSA, and it was constructed by a joint venture of Kumagai Gumi Co. and Kajima Co. Nagata Acoustics served as the acoustical consultant for the room acoustical design of the Public Hall and also developed the sound and vibration isolation design for the entire AOSSA complex. The combination of commercial, city and prefectural occupants in the building required that our acoustical structural design pay careful attention to creating effective sound and vibration isolation, since the building contains many rooms and spaces dedicated to disparate uses.

<< The Prefectural Public Hall's Opening Concert >>

Interior of the Public Hall
Interior of the Public Hall

On Wednesday, June 27, AOSSA Hall's first hall-sponsored concert opened the hall with a program of short works for voice and piano. Tenor Nobuyuki Kato and soprano Emi Sakamoto, accompanied by pianist Takehiko Yamada, performed selections well chosen to appeal to a broad audience of all ages, from children to seniors. Mr. Yamada's piano playing sounded forthright and delightful, and the performers achieved an excellent balance between the opera singers' voices and the piano accompaniment. During a talk given from the stage, the speakers' amplified words could be heard clearly by the audience. The one unfortunate aspect of the event was the relatively low attendance of about 150 people, a disappointing turnout given that the occasion was the hall's inaugural concert. The entity entrusted with operating the hall would have done well to be more proactive about advertising and promoting the event.

<< The Hall's Popularity as a Rental Facility >>

A look at the hall's rental bookings reveals about a 90% utilization rate through the end of this year. While many of the specific programs have not been made announced, the planned rentals are known to include a healthy variety of both music concerts and speaking engagements. The hall's immediate popularity with diverse performance and event organizers offers a glimpse of the local community's eagerness to use the new venue.

Currently, however, the hall's operating entity plans just four hall-sponsored concerts a year, too meager a number in this writer's estimation. Public halls must surely serve communities' needs for venues where residents can perform and express their creativity, and where students young and old can demonstrate their musical and thespian skills on stage. In addition to these purposes, public halls should also play a significant role in proactively fostering patronage of the performing arts by sponsoring and promoting concerts that raise communities' appreciation of a variety of art genres and their support of the performing arts industry.

AOSSA's URL is http://www.aossa.jp/.

Sound Isolation Design - Supplement 1:
Noise Legislation and Regulations

by Fumiaki Sakamaki

When New York's new noise code took effect on July 1 of this year, the Japanese media reported the code's new provisions and New York's approach to the problem of noise. In addition to targeting expected noise sources, such as construction noise and car alarms, the new code also regulates the loudness of personal earphones and barking dogs. Fines range from US$50.00 (36.5 EUR) for plainly audible noise from personal headphones to $175.00 (128 EUR) imposed on pet owners for their pets' unreasonable continuous barking in excess of 10 minutes during the daytime and in excess of 5 minutes at night.

New York's new code is one example of legislated noise regulation. Japan's governmental bodies also address noise in national and municipal-level laws and codes. At the national level, in Japan's Basic Environmental Law, Paragraph 16, Subsection 1, the government established its regulatory role "related to air pollution, water pollution, soil contamination and noise," stating that it "shall respectively establish environmental quality standards, the maintenance of which is desirable for the protection of human health and conservation of the living environment."

<< Japan's Environmental Quality Standards for Noise >>

Japan's Environmental Quality Standards for noise specify permissible noise levels from the perspective of the general public that would hear the noise under specified situations and circumstances as administrative improvement goal on the enforcement of the anti-pollution measures.
The noise standards include:

  1. Environmental quality standards for noise in general geographic locations and in geographic locations proximate to roads and vehicular thoroughfares;
  2. Environmental quality standards for aircraft noise in geographic locations within certain distances of airports; and,
  3. Environmental quality standards for Shinkansen ("bullet train") Super-express Railway noise.

In addition to categorizing standards based on these three criteria, the Japanese government recognized that the required level of quietness varies by region and other factors. The governors of Japan's prefectures define and designate the noise levels for different types of their prefectures'areas. For each type of area, there are two environmental quality standards for noise, one applicable to the typical awake hours of most people (6:00 a.m. to 10:00 p.m.), and another standard for nighttime hours (10:00 p.m. to 6:00 a.m.). The standards' rule for evaluating an area's noise level is to use the equivalent continuous A-weighted sound pressure level basically throughout all the hours of each of the two segments of time. Using the evaluations as baselines, the government recommends sound pressure levels of noise conducive to pleasant living environments. However, the environmental quality standards represent purely the government's policy targets for improvements against environmental pollution; they are not regulations affecting specific noise sources.

<< Japan's Noise Regulation Law >>

Some Stipulations of Japan's Noise Regulation Law
Some Stipulations of Japan's Noise Regulation Law

In Japan, the Noise Regulation Law regulates noise generated by specific sound sources. The accompanying table lists the noise sources we encounter in daily life that are covered by Japan's Noise Regulation Law. For each of these kinds of noise, the law specifies the maximum permissible noise level. It is worth noting that certain cultural facilities are included in the category of "specified kinds of factories." The cultural facilities covered by this regulation have equipment that falls within the regulation's specified factory equipment definitions, specifically air compressors and blowers with a rated output of 7.5 kW or more.

<< Local Ordinances and Sound Isolation for Cultural Facilities >>

In addition to regulations enacted at the national level, some prefectures and cities enforce local regulations, to control the loudness of sound amplification equipment. In the course of Nagata Acoustics' consulting work, when a project's construction is completed, it is not unusual for us to test whether events held in the new facility can be heard outside. To perform the test, we generate sound inside the facility at the level anticipated from events to be held in the venue and, at the same time, we use instruments or the human ear to measure the sound level heard at the perimeters of the facility's site.

Without question, acoustical consulting work for cultural center projects includes designing sound isolation to prevent external sounds from penetrating into the facility. Depending on the project's location, sound produced inside the facility may cause problems for neighboring properties. Even where no specific local laws exist or when they do not apply to the project's circumstances, we consider it important for the acoustical consultant to grasp the project site's surrounding environment and assess the need to provide sound isolation that limits or prevents sound from being heard outside.

Ministry of Environment's URL is http://www.env.go.jp/en/laws/.

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

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Los Angeles, CA 90025, U.S.A.
Telephone: (310) 231-7818
Fax: (310) 231-7816

E-mail: info@nagata.co.jp

[ Japanese Version ]