Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 09-09 (No.261)

Issued : September 25, 2009

[ Japanese Version ]

Sound Environments in Primary School Buildings: The Sakurayama Primary School, Takasaki City Project

by Toshiko Fukuchi

Takasaki City's Sakurayama Primary School opened to its first semester this past spring. The school serves more than 500 students in the north part of the city that was formerly the Gunma-machi unincorporated township called Gunma-machi.

In recent years, this part of Takasaki City experienced significant development of its road infrastructure, added a large shopping center and became a popular location for the development of residential housing. As the area became a bedroom community for the city, the population of primary school-age children also grew. To alleviate the increasing strain on the existing primary schools due to the rapidly increasing size of their student populations, the city built the new Sakurayama Primary School. Waseda University Professor Nobuaki Furuya and his architectural firm, Studio NASCA, created the architectural design for the new school.

<< Architectural Institute of Japan Acoustical Standards for School Buildings >>

The Architectural Institute of Japan published the "Academic Standards and Design Guidelines for Sound Environment in School Buildings" (AIJES-S001-2008) in March, 2008. As I was the chief examiner for the Guidelines, I shared information from the Architectural Institute's guidelines with Ms. Sachiko Yagi, one of Studio NASCA's directors, including the importance of proper sound isolation and sound reverberation characteristics in school environments. Studying about the importance of acoustics in a school environment, apparently she decided to request Nagata Acoustics' participation on the Sakurayama Primary School project.

<< Highlights of the Sakurayama Primary School Architectural Design >>

Mt. Haruna seen in the distance beyond Sakurayama Primary School (Photo by Satoshi Asakawa
Mt. Haruna seen in the distance
beyond Sakurayama Primary School
(Photo by Satoshi Asakawa)

Multipurpose space at Sakurayama Primary School (At right: a classroom)A suspended ceiling grid above classrooms and the multipurpose space supports a layer of glass wool (wrapped in glass cloth) below the ceiling's slab, creating a sound-absorbing surface.The wall section at left (opposite the classroom shown at right) is made of openwork wood backed by sound-absorbing polyester wool (wrapped in glass cloth).
Multipurpose space at Sakurayama
Primary School (At right: a classroom)
(Photo by Satoshi Asakawa)

A suspended ceiling grid above
classrooms and the multipurpose
space supports a layer of glass wool
(wrapped in glass cloth)
below the ceiling's slab, creating
a sound-absorbing surface.

The wall section at left (opposite
the classroom shown at right) is
made of openwork wood backed by
sound-absorbing polyester wool
(wrapped in glass cloth).

Sakurayama Primary School is located south of Mt. Haruna on land that is part of the mountain's foothills and has a gradual slope. The footprint of the school's two-story building has an architectural design that folds back and forth along the site, extending for a total of 150 m. (492 ft). The second floor houses all of the classrooms for grades one through six, leaving the first floor reserved for specialty classrooms and other uses. The second floor is built in a level plane, while the first floor is built in conformity with the site's sloped ground, so that the first-floor rooms at the south end of the property have higher ceilings than the first-floor rooms at the north end. High ceilings create a more desirable environment for music classrooms, so Prof. Furuya and Studio NASCA designated the classrooms at the south end of the building for this purpose.

The school's interior floor plan uses the currently popular "open plan" arrangement. Compared with typical school floor plans of the past, spaces that formerly would have been corridors outside of four-walled classrooms have been widened for multipurpose use, and there are no walls between the multipurpose spaces and the classrooms.

<< Achieving an Excellent Sound Environment in an Open Plan School >>

The previously mentioned "Academic Standards and Design Guidelines for Sound Environment in School Buildings" publication reports that the three most frequent complaints about school sound environments are: ineffective sound isolation between classrooms in open plan schools; insufficient sound reverberation in music classrooms; and, excessive sound reverberation in gymnasiums. The publication provides precautions to consider during a school's architectural design phase in order to avoid each of the three problems. Concerning classroom sound isolation in open plan school layouts, the publication mentions, in general, the importance of good sound absorption in the multipurpose space. More specifically, the publication emphasized the necessity of having a sound-absorbing ceiling and the effectiveness of sound absorption materials along the wall sections of the multipurpose space that are opposite classrooms.

The acoustical design of Sakurayama Primary School precisely follows the recommendations of the published guidelines. For our ceiling design, below the concrete slab we installed a suspended ceiling grid system that supports a layer of glass wool wrapped in glass cloth. Also, along the wall sections of the multipurpose space across from classrooms and that face the dividers between classrooms, we installed sound absorbing surfaces made of openwork wood backed by sound-absorbing polyester wool wrapped in glass cloth.

On May 9, 2009, Sakurayama Primary School held a well-attended open house. Despite the large number of people in the building, there was no annoying sense of chatter, the voice of the persons providing explanations could be heard easily and clearly and, overall, the acoustics alleviated any unpleasantness from the sounds generated by the many people in the building. I was especially happy when one architect attending the event approached me and said that, while he previously had not given much thought to the topic of sound absorption, he now realized that sound absorption measures can be extremely effective.

<< Workshops Help Prepare the Community for an Open Plan School >>

Prof. Furuya and his Studio NASCA hold detailed community workshops during all of their projects. For this project, the workshops focused on the difference between Sakurayama Primary School's "open plan" interior and the interiors of other, nearby primary schools, all of which have traditional floor plans with corridors along one side of their buildings and rows of four-walled classrooms facing onto the corridors. Using computer simulations of the "open plan" design, Prof. Furuya and his team brainstormed with the community to find effective ways to derive the full benefits of the new school building.

The issues that arise with open plan school layouts can also be mitigated by the way that the school uses the classrooms and the multipurpose space. The community workshops that explored effective ways to use the open plan school will surely help prevent the school from using its new building in ways that might result in later complaints.

<< School Environments that are both Pleasant and Promote Learning >>

Children spend a large portion of every day in school. Therefore, it is essential that schools should have a pleasant and invigorating atmosphere, but they also must have environments conducive to the kind of focus and concentration needed for the fundamental purpose of schools, which is learning and study.

These ends can only be achieved by including consideration of the acoustical environment. Recently, more Japanese schools are being built that have appealing architectural designs and thoughtful implementation of effective acoustical environments. Sakurayama Primary School is one excellent example of this trend. I hope that schools such as this one will serve as models for other similar efforts and stimulate further improvements in the acoustical environment of primary school buildings.

16th Aichi Performing Arts Technical Professionals Seminar

by Dr. Minoru Nagata, Founder of Nagata Acoustics

For the two days of July 14 and 15, performing arts technical and management professionals, came together at Aichi Prefectural Arts Theater to attend and participate in a seminar jointly sponsored by the Aichi Arts Foundation and the Stage Management Union of Aichi Prefecture. The theme of this 16th annual gathering was "Theaters at a Turning Point, Part 4: Technical Stage Expertise in an Era of Major Transformations." The seminar's lecture topics and speakers can be seen on the accompanying seminar program.

The lectures presented at the seminar can be divided into two broad categories. One category included talks about government cultural policies, the system for evaluating and measuring the performance of stage management organizations, proposals for theater safety and recent trends in cultural institutions. This category presented various perspectives related to the operational aspects of halls and theaters.

The other category of events on the seminar program intentionally highlighted the disparate acoustical characteristics of the Aichi Prefectural Arts Theater's opera house and concert hall. The program included both a performance by a chamber music ensemble and a two-actor play, providing the seminar attendees with first hand experiences of both reverberant concert hall acoustics and the way the spoken script lines of the human voice sound in the same setting.

<< An Invitation and My Event Topic: Sound Amplification in Concert Halls >>

I received an invitation to participate in this seminar from stage lighting consultant, Mr. Juko Sato, who serves as a committee member to help plan and implement the seminars. Mr. Sato asked me to speak both about the basics of architectural acoustic design and about how amplified sound is heard in concert halls, which is a topic garnering increased attention in recent days. Now that concert halls have been built in many Japanese communities, and with the marked increase in multipurpose halls that are being built primarily for use as concert halls, I agreed that the time was ripe to address the seminar gathering on the topic of amplified sound in concert halls.

For this event, I enlisted the collaboration of two people, Mr. Katsuji Naniwa, a principal of M&N Sound Projects Inc. and former Nagata Acoustics sound system consultant, and his assistant, Ms. Asako Chiba. Together we arranged to demonstrate, in real time, actual measuring of the reverberation times of the venue's two halls and to set up several types of loudspeakers so that the seminar attendees could directly experience the differences in how various loudspeaker setups sound. We aimed to use these direct experiential means to deepen the seminar attendees understanding of hall acoustics.

<< Talks on Japan's Theater Laws and Regulations Started the Seminar >>

The first two talks of the seminar's first day presented: (1) a report from the Agency for Cultural Affairs Policy Subcommittee; and, (2) recommendations for legislation related to theaters. This was my first opportunity to learn about these possible Japanese legislative initiatives and I appreciated the opportunity to hear these lectures because I am interested in how the architectural professions will respond to the proposals.

The third presenter on the agenda discussed the operational administration of theaters in Japan and, in particular, the system known as "Shitei-kanrisha-seido" that came into effect nine years ago and allows publicly funded halls to contract out their operational and administrative work to private companies. This lecture focused on the economic realities behind the aims that led to the current system and the current system's deficiencies. This seminar lecture suggested that there will soon be changes in the laws and regulations governing theater operations in Japan.

Table-1 Seminar Program
Table-1 Seminar Program

<< Planned "Keynote" Speaker Prof. Kyonosuke Kotani's Untimely Passing >>

The seminar organizers had invited Nihon University Prof. Emeritus Kyonosuke Kotani to deliver the seminar agenda's fifth topic, a lecture surveying the transitions and technological progress of Japan's theaters since the end of World War II. For this address, which could be considered the seminar's keynote presentation, Prof. Kotani put the full force of his profound knowledge and veteran theater consulting experience to prepare a talk of invaluable technical and historical detail. Unfortunately, Prof. Kotani's failing health prevented his appearance and, at the "eleventh hour," theater consultant Mr. Toshiya Kusaka took the lectern instead of Prof. Kotani. Mr. Kusaka gave a talk that focused on current trends in Japan that distinguish today's situation for theaters and halls from the situations of previous decades.

In his presentation, Mr. Kusaka provided data comparing the number of halls built in Japan during the past economic boom to the number of halls being constructed in today's recession economy. His data showed a precipitous drop in hall construction and he noted that if present-day trends continue, the number of halls being built could drop to zero, a shocking possibility.

Prof. Kotani truly wanted to be part of this seminar, regardless of his being wheelchair-bound, and the seminar organizers hoped for his arrival until the last possible moment. Regrettably, Prof. Kotani passed away the following July 28, at Tokyo's Red Cross Medical Center where he had been hospitalized. I extend my prayers and condolences at this loss of one of Japan's titans of theater consulting.

<< Our Architectural Acoustics Lecture and Demonstrations >>

Chamber music performance (the concert hall)
Chamber music performance (the concert hall)

A two-actor play (the opera house)
A two-actor play (the opera house)

Arrangement of sound systems loudspeakers on the stage
Arrangement of sound systems
loudspeakers on the stage

On the seminar's first day, I delivered a lecture on the "Essence of Architectural Acoustics". On the seminar's second day, the program's emphasis shifted to topics of immediate practical and technical benefit to the attendees, and M&N Sound Projects' Mr. Naniwa and Ms. Chiba began this day in the Aichi Prefectural Arts Theater's opera house with a demonstration of how acoustical consultants measure a hall's sound reverberation time. We developed this demonstration to increase the attendees' understanding of how sound reverberation and sound reverberation times affect both audience sensory perceptions and the physical properties of a hall.

During the demonstration, the seminar audience experienced with their ears and bodies the sound decay of test sound emissions. The audience also watched on a large projector screen as we viewed and explained the decay wave patterns of sound reverberation times and how we read the sound reverberation time from the displayed information.

For the next event on the seminar's agenda, we had chamber music and a two-actor play performed in the opera house (the venue's larger hall) and the concert hall to do a live, experiential comparison of the venues' acoustics. When I listened to the acoustical differences between classical music performed in these two venues and the difference in the way spoken lines from a script sound in the two venues, even I was surprised by how obvious and striking the differences were. In the opera house, the demonstration included listening to the chamber ensemble with several different sound-reflecting surfaces, such as a folding Japanese screen, placed on the stage behind the ensemble. Nevertheless, for the acoustical quality of chamber music performances, we confirmed the limited degree of improvement possible in this venue. Similarly, in the concert hall, we confirmed the limitations on the ability of an audience to hear the actors speaking their script lines on the stage.

The demonstrations in the opera house and concert hall convincingly make the case for the necessity and usefulness of amplification systems. However, because the seminar organizers recognized that there is widespread dissatisfaction with the speech amplification functionality in many halls, the seminar agenda followed the demonstrations with participation by me and Mr. Naniwa in a symposium-style discussion about concert hall sound system issues.

<< Symposium-style Discussion on Concert Hall Sound System Issues >>

I opened the discussion about concert hall sound systems by raising a number of non-technical issues. One problem is that, in general, concert hall owners and architects do not include speech amplification as a priority in their concert hall projects. Another problem stems from the way that people speaking from a stage hold the microphones.

After my comments, M&N Sound Projects' Mr. Naniwa explained that a sound system's loudspeaker selection and loudspeaker placement significantly influence the way an audience hears amplified speech in a concert hall. Mr. Naniwa had arranged for 4 loudspeakers by Japanese and other manufacturers to be brought to the hall for this discussion and he used these units and the loudspeakers installed in the Aichi Prefectural Arts Theater's concert hall to conduct sample demonstrations of amplified speech for the seminar audience's comparison. During this session, members of the audience moved to several different seating locations to hear the amplified speech in various hall locations and avidly participated in this opportunity to experience and compare the loudspeaker systems and the effects of loudspeaker placement adjustments.

<< Juko Sato's Talk on Reducing Lighting Fixture Noise in Concert Halls >>

The last topic of the two-day seminar discussed the common concert hall problem of noise from lighting fixtures. Lighting consultant Mr. Juko Sato presented strategies and measures that halls can adopt to reduce this kind of noise.

<< In Praise of the Aichi Performing Arts Technical Professionals Seminar >>

During the 1970s and 1980s, when Japan's hall construction boom was at its height, the Association of Public Theaters and Halls in Japan held annual seminars like the Aichi Performing Arts Technical Professionals Seminar in numerous regions around the country. Now that the organization responsible for those seminars has disbanded, gatherings that comprehensively address the needs of stage technical professionals have mostly disappeared and have been replaced by lectures and seminars focused on narrowly defined topics of appeal to specific theater or hall interests. In this environment, I was amazed to learn that a seminar such as the Aichi Seminar survives, not in Japan's largest Tokyo or Osaka cities, but rather in Nagoya.

The Aichi Performing Arts Technical Professionals Seminar is all the more noteworthy for its longevity of 16 years of meetings, especially given the economic downturn that has had a chilling effect on the Japanese theater industry. Attending the seminar, I felt that it was like a beacon of light guiding the way for the industry.

The two-day seminar included a broad range of lectures and events. The implementation planning for the seminar and the leadership demonstrated by both Mr. Sachiaki Mano, Chairman of the Stage Management Union of Aichi Prefecture and key staffer Mr. Juko Sato resulted in two satisfying days for both participants and attendees. Also, the Aichi Prefectural Arts Theater crew provided timely and professional support and I wish to thank them for their quick thinking and expeditious work.

Stockhausen's "Gruppen" Performed at Suntory Hall

by Akira Ono

In our July, 2009 newsletter, I wrote about the upcoming NHK Symphony Orchestra performances of Stockhausen's "Gruppen" at Suntory Hall. As planned, the concerts took place on August 31, 2009. (Please see the July article for the orchestra's placement in the hall for these performances.)

Previous to the Suntory Hall performances, the first performance of "Gruppen" in Japan took place 35 years ago, in February, 1974. The venue was NHK Hall, which had just recently opened in Tokyo's Shibuya Ward. Maestros Tadaaki Otaka, Hiroyuki Iwaki and Kazuhiko Komatsu led the NHK Symphony Orchestra in this inaugural performance at a regular subscription concert. The placement of the orchestra musicians for this performance can be seen in the accompanying photograph. All three orchestras were located on NHK's fixed stage at the front of the auditorium.

<< Stockhausen's Detailed Instructions for "Gruppen" Performances >>

The February, 1974
The February, 1974 "Gruppen"
performance at Shibuya's NHK Hall
(Photo provided by NHK Symphony Orchestra)

In addition to the musical composition itself, the "Gruppen" score contains detailed instructions about the performance venue, the placement of the instruments, how to rehearse the composition, and even how many rehearsals to hold. One question for producers of concerts that feature this composition is how faithfully to follow Stockhausen's copious instructions. For example, when Maestro Sir Simon Rattle and the City of Birmingham Symphony Orchestra performed "Gruppen," we can see on the YouTube recording that the string and percussion sections were located at the right side of the conductor and the wind instruments at his left side, reversing the standard left-right orientations of these instruments, perhaps in order to help the sounds of the string instruments reach the audience.

The layout for the Suntory Hall performance follows Stockhausen's stipulations closely. The audience seating surrounded the orchestra and, overall, the placement of the instruments adhered closely to Stockhausen's instructions. According to the score, four percussionists should be included in each of the three orchestras. On this point, the Suntory Hall production took the liberty of a slight divergence and employed five percussionists in each orchestra to play the many percussion instruments included in the score.

<< Describing the "Gruppen" Experience >>

On the day of the "Gruppen" performance, some 300 to 400 ticket holders lined up early in the day so they would increase their chances of sitting in the seats they desired. The concert program began with Ligeti's "Clocks and Clouds." Following this piece, musicologist Mr. Shinichiro Okabe appeared on stage with the "Gruppen" conductor, Maestro Susanna Maelkki and the sound director Mr. Yoichi Sugiyama, while the orchestra configurations were being set up for "Gruppen," they discussed the composition and explained it for the benefit of the audience.

Ms. Maelkki described her impression of "Gruppen" as that of listening to sound swirling around one and rising upward towards a climax. I sat in the first floor audience seating for the performance that followed and can attest that this description truly fit my experience.

Simon Rattle compared the structure of "Gruppen" to the mobiles of Alexander Calder, a contemporary of Stockhausen. Mobiles have fixed elements connected to other fixed elements. When one of the elements moves, the movement triggers the other elements to also move. At Suntory Hall, the audience who sat in seats that enabled a full view of all three orchestras reported that other than noticing the eye contact among the three conductors, each of the orchestras performed seemingly independently of the other orchestras. Nevertheless, while music would well up separately from each of the orchestras, there were also times when the music of one orchestra seemed to blend with the music of one of the other orchestras so that they built on one another the way a mobile moves to form and reform, sometimes seeming to be separate elements and sometimes combining into a whole.

At Suntory Hall, the clear directionality of the "Gruppen" composition and the music's combining and melding of sounds showed off the hall's acoustics. It was clear to me that the performance of "Gruppen" at Suntory Hall was inevitability brought to fruition, because the hall's acoustics suited the work so very well.

<< Future Listening to "Gruppen" May Be on a Headset >>

NHK Broadcasting says it has no plans to broadcast the recording made of the "Gruppen" performance at Suntory Hall. The NHK Science and Technology Research Laboratory recorded the concert in a 96-channel format. Eventually, the recording will be reproducible in the 22.2-channel Super Hi-Vision format being developed by the research lab. According to the research lab's website, the lab is also developing headphones for the consumer market that will be able to faithfully reproduce the "Gruppen" concert experience. I look forward to the day when a set of headphones can give me the sense of immediacy and presence today enjoyed only when sitting in a concert hall.

Nagata Acoustics Inc.

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[ Japanese Version ]