Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 07-03 (No.231)

Issued :March 25, 2007

[ Japanese Version ]

Komazawa University Music Practice Facility Completes

by Nobuhiko Hattori

In Japan, the mention of Komazawa University conjures up images of intercollegiate sports such as the Hakone Ekiden marathon relay race, soccer and baseball. Last summer, during the famous annual Koshien high school baseball tournament, Japan became all the rage with talk of the thrilling effort Komazawa University's sister high school displayed in its game against Waseda Jitsugyo High School, a team favored because of its star pitcher, "the handkerchief prince" (so nicknamed because of his habit of wiping his brow with a handkerchief).

Komazawa University's main campus is located in Tokyo's Setagaya Ward, adjacent to Komazawa Olympic Park, where the 1964 Olympics held cycling events. Neighborhoods of private homes ring both the park and the campus. The boulevard that runs along the front of the campus serves as a thoroughfare for both students coming to and from classes, as the gateway to the park for running enthusiasts, children, dog walkers and others who use the park, as well as simply a pleasant place to take a stroll by residents of all ages.

Into the midst of these residential surroundings, the university devised a plan to renovate the main building on the Komazawa University campus so that part of it would serve students and student groups as a music practice venue. The project's planning phase began in 2005 and, in January 2007, the project completed.

<< The Project's Key Objective, Constraint and Challenge >>

After class hours, the coming and going of students diminishes and the residential neighborhoods near the university become rather quiet. In consideration of the nearby residents, the university had imposed strict rules on music practice by student clubs and groups limiting the hours when classrooms could be used for practice and whether or not windows could be opened during music practice.

To provide a venue where student musicians can practice and produce loud volume sound without worry, the school administrators proposed that the basement of main building being used as storage space be converted into practice rooms. However, the building above this basement houses offices and classrooms that would need to be isolated from the sound produced in the basement. Preventing the transmission of sound from the basement to the upper floors became the main challenge and consideration for Nagata Acoustics on this project.

<< Overview of the Renovation Plan >>

The renovated facility occupies about 1,400 sq. m. (15,070 sq. ft) of the Komazawa campus' main building basement and has both practice rooms and musical instrument storage space. The 13 practice rooms of varying sizes, ranging from 21 sq. m. (226 sq. ft) to 73 sq. m. (786 sq ft), line both sides of one long, straight, narrow hallway. Some of the smaller practice rooms are specifically designated as practice space for soloists and individuals practicing their parts of an ensemble performance.

To enliven the facility's simple, rectangular space, the interior design's color scheme uses bright red, blue or green paint for the practice room doors and large painted circles on the floors, making it easy to forget that the rooms are in a basement. For those who remember the cluttered, dingy warehouse look of the basement before the renovation, the before-and-after comparison of the upbeat makeover creates an even stronger impression.

The project's architectural design firm was Engineering Service Inc., and Kumagai Gumi was responsible for the renovation construction. Nagata Acoustics designed the acoustics, focusing primarily on the sound isolation plan, provided consulting services during the construction phase, and performed acoustical measuring of the renovated space.

Music practice facility floor plan

Inside a practice room

<< Sound Isolation Planning Part 1 - Pre-renovation Evaluations >>

In the first stage of planning this project, we investigated the existing sound isolation properties of the basement's structure. We also measured and evaluated the performance sound volume of the student groups who would practice in the facility, including pop music clubs and the school's powerfully voiced cheerleaders, a staple of the school's intercollegiate team sports competitions. The purpose of these evaluations was twofold. First, the evaluations obtained device-measured data on the physical sound isolation properties of the building and the sound levels of the students' music. Second, by listening to the pre-renovation sound with the client, the architect and the construction contractor, we gained their recognition and understanding of the necessity and importance of sound isolation performance for the success of the project.

The results of our pre-renovation testing revealed sound isolation performance between the basement and above-ground floors of Dr - 55. (The "D" rating is a Japanese standard for measuring sound isolation performance.) As for the sound level of the student performances (that is, the equivalent continuous sound pressure level), they reached over 100 dB across a wide band of frequencies from 63 Hz to 1 kHz. Bass guitar, drums and the voices of the cheerleaders could all be heard in the building's above-ground floors. In particular, the sound from the cheerleaders' large drum was transmitted into the building structure, creating vibration that the client and those who were involved in the project could feel beneath their feet. This first-hand experience impressed on them the importance of including anti-vibration design strategies in the renovation construction.

<< Sound Isolation Planning Part 2 - The Implemented Anti-vibration and Sound Isolation Strategies >>

Structure for Anti-Vibration and
Sound Isolation

Result of sound
transmission measurement
after the renovation

On this project, we were required to constrain the scope of the renovation work to within the existing basement structure, so we aimed to implement the highest possible anti-vibration and sound isolation specifications while respecting this limitation. The subcontractor YACMO was responsible for implementing our design, on-site, during the construction phase of the project.

As shown in the accompanying section drawing, in order to prevent the transmission of sound from the practice rooms to the existing building structure, we specified anti-vibration material (rubber damper) as a substrata layer under all the practice rooms floors and we stipulated that interior walls and ceiling be supported by the practice room floors. We designed a box structure for the practice rooms, making them structurally and acoustically separate from the existing building structure and we used the surrounding, existing ceiling, walls and some previously added drywall as a sound isolating structure.

We also made allowance for practice room doors being left ajar during music practice sessions and for instruments being played in the corridor by applying anti-vibration and sound isolation designs to the hallway space as well. For the floor of the corridor, we adopted "Multi Adjustable Floating Floor method" (a construction method of anti-vibration structure, which reduces construction period) and we suspended the corridor ceiling from the existing ceiling using anti-vibration support hangers. We also used these hangers to prevent the transmission of sound from the practice rooms and corridor to existing ceiling structure through the basement's large ductwork.

Based on the measurements we obtained after the completion of the renovation construction, the sound isolation performance between an office on the building's first (ground) floor and the practice room directly beneath it rates a value of Dr - 75 to 80, the rating between the office and practice rooms located at a distance is Dr - 85 or more and the sound isolation performance between the first floor office and the music practice facility corridor is Dr - 60 to 70. The sound isolation between practice rooms is mostly Dr - 85 or greater.

<< Post-completion Measurements and Operational Use of the Facility >>

After the project's construction completed, and before the facility was opened for general use this spring, we repeated the performances by pop music clubs and by the university's cheerleaders under the watchful eyes and ears of the client and other project stakeholders. When the cheerleaders pounded out a strong rendition of the school's song, sung with the force of generations of tradition, we discovered that the sound isolation performance mitigated the transmission of sound to the extent that the large drum could be heard just faintly in the office directly above the practice room. (Some background noise conditions contributed to the ability to faintly hear the drum in the office.) Based on these results, the need for students to worry about playing too loud during music practice is now a concern of the past, and Komazawa University's students may practice music to whatever decibel levels their muses may lead them.

The physical installation of anti-vibration and sound isolation measures is truly behind-the-scenes work. When project construction completes, the anti-vibration and sound isolation structures and materials are not visible to the people who use the facility and, conversely, the construction crew that builds the anti-vibration and sound isolation performance capability into a structure rarely see the expressions on the faces of a facility's users when they notice the quietness in a room. On this project, we created the chance for the client, the builder and other stakeholders to hear the musicians who will use the practice rooms perform both before and after the renovations. Because the client and other stakeholders heard the sound isolation and anti-vibration performance of the space both before and after the renovations, they were able to directly validate the expanded opportunities for the facility's use that resulted from the adoption of our sound isolation and anti-vibration design, and they shared the ownership for making the right decisions and building the renovation per the acoustical design specifications.

I hope this new music practice space will be used to the fullest. May it serve as the springboard for many talented young musicians to further their musical aspirations.

Iwaki Diamond Project Graduation Event "Live Yazzo!2"

by Masaya Uchida

On a crystal clear January 28, 2007, the Iwaki Diamond Project Graduation Event "Live Yazzo!2" energized participants and the audience for the second year in a row at Iwaki City's Taira Shimin Hall. The Iwaki Diamond Project is a performing arts training program sponsored by the city as part of its preparations for next spring's opening of the new Iwaki Performing Arts Cultural Exchange Center, ALIOS, which is currently in the construction phase of development.

On stage during "Live Yazzo!2"
(photo courtesy of The Diamond
Project Organizing Committee)

The Iwaki Diamond Project lets local residents experience a more active role in performances than they have when they enjoy performances sitting in the audience. The program's four courses teach participants to plan and manage performances, develop technical stagecraft capabilities and take the stage as performance artists; and the project concludes with a live graduation performance in which the participants put into practice what they have learned. By sponsoring these courses, the city aims to stimulate the appetite of local residents for taking an active role in the performing arts so that those who are talented and interested will become a pool of future resources to nurture Iwaki's performing arts. The city put the word "diamond" in the project's name to express the hope of finding valuable talent hidden within its own borders.

Repeating last year's successful approach, the project's four courses included: event planning and management; stage lighting; stage directing and stage design; and artistic expression. The focus of this year's artistic expression course was hip hop dance. While young women in their twenties represented the largest demographic attending these courses, the courses attracted people from their teens to age 71 and an astounding total of 200 people participated overall. During five months of instruction, the participants studied their chosen disciplines with instructors who are currently active in the industry as well as known for their outstanding work in their fields. The results of these months of study, learning and practice culminated in the live graduation performance.

On the day of the graduation event, a long line of the participants' eager friends and relatives crowded the area in front of Taira Shimin Hall. The strong turnout testified to the successful grassroots efforts and publicizing of the event by the event planning and management course participants. Their joy at seeing the large audience was palpable. The Iwaki City employees with a connection to the project, Shimin Hall or ALIOS also showed up in full force to attend the graduation event.

After guest performer opened the show, the main graduation event began. As the curtain rose, the audience saw an empty stage. Then, out came the graduates who had studied stagecraft. They mopped the stage floor, placed the scenery and other stage props-all of which were made by the students-on stage and the stage lighting course graduates set color filters in their holders. The stagecraft and other normally "backstage" roles thus took the spotlight as part of the graduation event. When all the stage preparations were in place, the artistic expression course graduates came on stage. The dancing began with soloists, then more and more of the graduates joined the performance, demonstrating their skill at stomp, break dance and hip hop. Every dance number was full of exuberance as both dancers and audience clearly enjoyed every minute of these performances, while some members of the audience shouted "oos" and "aahs," encouraging performers' especially extreme moves.

A more formal graduation ceremony followed the "Live Yazzo!2" performance. I was particularly impressed by a comment made by the valedictorian, who spoke with confidence and vigor, saying that before taking the course each day passed uneventfully without any particular focus. By participating in the Iwaki Diamond Project course, every day of life was now different.

Another salutary result of the project was the bonds of friendship the participants formed across generational lines. In addition, this project's stated goal to nurture and train local talent to become the city's future performing arts professionals and the project's hands-on approach of having students plan, produce and perform a live performance won recognition from the Japan Association for the Promotion of Creative Events (JACE). The project won JACE's Japan Event Grand Prize in the production category. This accolade from an industry-wide organization surely brought great joy to the Iwaki Diamond Project students, the project organizers, course instructors and everyone involved.

The Taira Shimin Hall building has been used for four decades, and while the Iwaki Diamond Project students gave their energetic Live Yazzo!2 graduation performance, the structure's age and visible wear and tear were of no concern and did not put so much as a dent in the gala atmosphere of both audience and performers. At this event, I reaffirmed my conviction that the people who gather at a concert hall or theater have the power to determine the vitality of the venue. I do not know what future plans the city may have for the Iwaki Diamond Project, but I do hope that, when the new Performing Arts Center opens, Iwaki City will continue to foster and sponsor the human and creative aspects of the performing arts as well as the bricks-and-mortar of the new facility. Like a two-person team running a three-legged race, the people who plan, direct, work backstage and perform, and the building in which they perform, will be most successful when they make progress, in lockstep, together.

Sapporo Shimin Hall's Closure and the Sapporo Symphony's Sayonara Concert

by Dr. Minoru Nagata, Founder of Nagata Acoustics

Sapporo Symphony Orchestra's
Sayonara Concert
(photo by Mr. Masahide Sato,
courtesy of the Sapporo Symphony Orchestra)

On the evening of January 19, 2007, in anticipation of the upcoming closure of Sapporo Shimin Hall (in March), the Sapporo Symphony Orchestra performed a Sayonara Concert to commemorate the hall. I had already heard reports about the hall's closure, but news of the Sayonara Concert reached me at the last minute. I immediately made the necessary arrangements and flew to Sapporo.

<< The Sayonara Concert >>

Before the start of this last concert in the hall, the hall and plaza outside were abuzz with patrons and when Music Director Tadaaki Otaka raised his baton to begin the concert, every seat in the house was filled. The program included the "Marriage of Figaro" Overture, Symphony No. 5 "Fate," and Symphony No. 9 "From the New World." For the encore, the orchestra played "Air on the G String." Keeping the strong emotions of the occasion from running amuck, the musicians gave a dignified performance during this swan song of Sapporo Shimin Hall. When the encore "Air on a G String" ended and a palpable silence followed, I sensed that Maestro Otaka profoundly felt the enormity of the moment. Among the audience, not a few heads were bowed reverently with tears in their eyes.

Following the concert, Sapporo Mayor Fumio Ueda ascended the stage and addressed the gathering with moving words. He spoke of Sapporo Shimin Hall as the birthplace of the Sapporo Symphony Orchestra. The orchestra was nurtured in this hall and then came into its own as a first class orchestra in its current home, Sapporo Concert Hall Kitara. The mayor likened the symphony orchestra's Sayonara Concert performance an act of filial piety, as the orchestra honored the "parent" that gave it life and sustenance.

<< Historical Highlights of the Hall and the Sapporo Symphony Orchestra >>

Sapporo Shimin Hall opened in 1958 at the east end of Sapporo's Odori Park Boulevard. Located next to the television tower, a Sapporo landmark, the hall contained 1,592 seats in a single-floor configuration, and was designed to accommodate both classical music concerts and many other performance and event genres. The hall's sidewalls have a mechanism for adjusting the hall's reverberation time, a feature that made this hall an innovative cultural facility at the time it was built.

As for the Sapporo Symphony Orchestra, its start came after the opening of Sapporo Shimin Hall. The orchestra was founded in 1961 as the Sapporo Citizen Symphony and held its first subscription concert in September of the same year, conducted by Maestro Masao Araya. According to the recollections of Mr. Yoshio Taketsu, then a horn player in the orchestra and, later, the orchestra's managing director, the orchestra first toured cities in the Tohoku northeastern region of Japan's Honshu Island, leaving Sapporo Shimin Hall as the last performance stop of its first season. When the orchestra's musicians heard the acoustics in the relatively new Sapporo Shimin Hall, their amazement and delight was as if they had "the scales removed from their eyes."

Shortly before I left on my trip to the Sayonara Concert, a journalist at one of Japan's daily newspapers called me to learn my opinion regarding the high esteem still accorded Sapporo Shimin Hall. As might have been expected, he focused his questions on the variable reverberation-time mechanism that was such a novel feature of the hall when it opened. At one time in the hall's history, the mechanism failed to function, setting off a debate among hall designers, builders and administrators about the merits and dangers of implementing variable reverberation-time mechanisms. For the Sayonara Concert rehearsals, the hall's reverberation panels were turned to their sound-absorbing side, demonstrating to the last the benefit of having a mechanism to effect subtle adjustments to a hall's reverberation time. Be that as it may, the true secret of this hall's admirable acoustics lies elsewhere. As I listened to the Sayonara Concert, I contemplated what made the acoustics of Sapporo Shimin Hall noteworthy.

<< Sapporo Shimin Hall's Acoustics >>

Surely, Sapporo Shimin Hall's acoustics do not share the brilliance found in recent halls such as Kitara Hall and Suntory Hall. The proscenium stage opening rises only to a low height and the hall's space typifies multipurpose halls of its era. However, the acoustics have a quality of moderation that might be visualized as molten sound of a certain viscosity around a resilient core, such that the sound comes flying out to the audience from the stage like a bound bundle of sound unleashed.

In my estimation, the secret to producing Sapporo Shimin Hall's acoustics, as with Tokyo Bunka Kaikan's acoustics, can be found in the sound diffusion pattern created by the onstage sound reflection panels and in the ceiling sound reflection panels that protrude beyond the stage over the front rows of audience seating. This structural design is difficult to achieve in most multipurpose halls.

Why does Sapporo Shimin Hall have such a textbook-perfect acoustical stage design? I think that the reason is that this hall was built before Japanese audiences began to demand authentic opera and theater acoustics for multipurpose halls. As specific performance genres lobby for their needs in competition with the acoustical needs of other performing arts genres, satisfying specific needs has chipped away at the kind of acoustical characteristics that defined Sapporo Shimin Hall.

Sapporo Shimin Hall fell victim to structural building problems and its closure became necessary a half century after it opened. Yet it seems that there are not many halls so beloved by their local communities. On the bright side, this hall gave birth and nurture to the Sapporo Symphony Orchestra, an institution that, without a doubt, will carry the tradition of great music to the next generation. I have the sense that this orchestra is already making great strides forward, bringing joy to the people and city of Sapporo.

Nagata Acoustics Inc.
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Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
Tel: +81-3-5800-2671, Fax: +81-3-5800-2672

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Telephone: (310) 231-7818
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E-mail: info@nagata.co.jp

[ Japanese Version ]