Title means "Quietness", "Comfortable Sound" and "Excellent Acoustics"

Nagata Acoustics News 04-05 (No.197)
Issued : May 25, 2004

Toho College of Music's New Glanz Saal Concert Hall

by Akira Ono and Makoto Ino

Exterior of Glanz Saal
In March 2004, Mimurodo Gakuen Toho College of Music celebrated the completion of its new Glanz Saal Concert Hall at its Kawagoe campus, located in a Saitama Prefecture suburb of Tokyo. The concert hall's construction commemorates the 65th anniversary of the founding of College.

The building of this new hall also comes at a time when new construction on Japan's music college and conservatory campuses has been flourishing. This flurry of construction aims both to reverse a trend of music colleges' decreasing popularity and to enable individual schools to differentiate themselves and thereby ensure their survival in Japan where decades of lower birth rates is now impacting the fate of institutions of higher education.

<< Overview of Glanz Saal Concert Hall >>

Nosu Architects designed the Glanz Saal building and interior, and Taisei Corporation served as the project's general contractor. The hall, which has one balcony, seats 620. It has an end-stage configuration and is designed specifically as a concert hall. The walls and ceiling of the stage are both fixed and there are no stage wings or a fly tower and therefore no structural elements from which to suspend a stage curtain. However, in order to enable rehearsals for opera productions and other performances that use an orchestra pit, the first three rows of the audience seating can be lowered using an electrical riser mechanism to create an orchestra pit.

<< A Design that Evolved as the Hall's Purpose Evolved >>

Interior of Glanz Saal
At the start of Glanz Saal's planning phase, the college's requirements were simply to build a large rehearsal space for orchestral performances. However, after some discussion, the project scope evolved to include audience seating. The addition of audience seating in turn led to the project's scope being further re-defined to become the building of a concert hall. The hall's design reflects the evolution of the project's definition. The hall's stage occupies a relatively large floor space area, and when the orchestra pit flooring is raised to stage height, creating a thrust stage, the stage floor space equals nearly one-half of the area of the hall's entire first floor. Toho College of Music required that an orchestra with quadruple winds be able to be seated on the hall stage, and the stage does meet this requirement by having space for 100 performers and their instruments. But from the perspective of the overall dimensions of the performance hall, the spatial volume is comparatively small.

<< Acoustical Characteristics of Glanz Saal Concert Hall >>

Because Glanz Saal is part of a college's facilities, it will be used for commencement exercises and other ceremonial events and gatherings. It will be used more frequently as a rehearsal venue than as the location of concert performances. To control the hall's reverberation time when it is used for ceremonies and rehearsals, we installed electrically operated, retractable curtains along the rear stage wall and the upper portions of the stage's side walls, as well as along the wall behind the audience seating area.

The hall's reverberation time (at 500 Hz, with the hall unoccupied) measures 1.6 seconds with the wall curtains fully retracted, and 1.2 seconds when the curtains are fully deployed. The range of possible reverberation times is therefore 0.4 seconds. In March, at the hall's inaugural celebration, the College deployed the curtains for the ceremonial first-half of the evening's program, then retracted the curtains after the intermission for a solo piano performance by one of the school's professors, concert pianist Mr. Kazuoki Fujii, followed by a string ensemble performance by professional violinist Ms. Atsuko Temma and some Toho College of Music students. After their performances, both Mr. Fujii and Ms. Temma gave the hall high marks from the performer's perspective. In addition to having satisfying acoustics, the electrically operated curtain mechanism contributed to a smooth transition between the two parts of the inaugural program, demonstrating effective use of this functionality.

<< Glanz Saal's Line Array Speakers >>

In keeping with Toho College of Music's intention that Glanz Saal will be used entirely for student -related activities (meaning a mix of use for ceremonies and for students' orientation, music practice, rehearsals and performances), the college focused its sound system requirements on just two capabilities: (1) clarity of amplified speech and (2) the ability to record performances. To accomplish these objectives without diminishing Glanz Saal's concert hall atmosphere, we chose slender, column-shaped line array speakers and embedded them in the corners formed by the sections of the hall's interior wall design. Each speaker opening is a mere 20 cm. (8 in.).

At the audience seating areas near the line array speaker units, the amplified sound has a somewhat unnatural vertical sound quality, but this disadvantage is outweighed by the speakers' ability to provide clearly amplified sound to each and every seat of the audience. Because the sound quality and sound volume distribution of these speakers are almost entirely determined by their physical positioning (angle), it was also important to keep in mind that the sound produced by these speakers cannot be readily adjusted simply by adjusting the electrical controls. At Glanz Saal, we installed a complicated design that used different speakers on the first floor than on the balcony and this complexity made our sound system tuning work more of a challenge than it would otherwise have been.

<< Glanz Saal's Live Recording Equipment >>

A three-point microphone suspension system is the most essential component of a hall's professional recording equipment set-up. The electrically operated mechanism for raising and lowering a three-point microphone suspension system costs several million yen (40-50,000 USD or Euro). We obtained the client's approval for this purchase separately from the project's budget and installed the mechanism in Glanz Saal. We selected high-end commercial quality microphones for these critical recording components and an economized on the mixing console by installing an inexpensive model that uses a 24-bit/96 KHz sampling format. Through this combination of components, we focused on achieving quality recording of music performed in the hall.

<< The Dilemma of Glanz Saal's Lighting Consultant >>

Toho College of Music retained Mr. Toshiaki "Juko" Sato as the project's stage lighting consultant, and Mr. Sato stressed to the client what he could and could not accomplish. Because Glanz Saal is a school facility, the lighting equipment needed to be convenient and relatively easy to operate, but the college also wanted high performance equipment with advanced functionalities. To some extent, Mr. Sato could select equipment with the potential to meet both sets of requirements, but the ability to make effective use of the equipment's high performance specifications and advanced functionalities requires professional stage-lighting expertise.

The role of the stage-lighting professional in creating an artistically satisfying lighting environment for a theater or hall stage continues to be undervalued. The lighting professional does not simply operate the stage lighting equipment in a pre-determined, mechanically rote manner. Rather, he or she must be artistically creative and draw on both creative vision and experience to improvise and create the stage's lighting to fit the specific circumstances of each performer and performance. Japan's recently enacted Culture and Arts Promotion Law inspired much discussion and debate, representing diverse perspectives, about the kind of talent and qualifications that the stage lighting profession and other back-stage professions require. For lighting equipment as for other theater arts, no matter how magnificent the quality of the equipment, in the end the equipment is only a tool and the tool requires an accomplished human being to realize and display what the tool can do.

When Toho College of Music's students practice and perform in their new Glanz Saal, the challenge of creating good stage lighting will be just one of the many first-hand learning experiences that will help them become discerning performers and concert hall audiences.

The Mimurodo Gakuen Toho College of Music website can be found at http://www.toho-music.ac.jp/.

The New Kashima Town Lifelong Learning Center's "Sakura Hall"

by Chiaki Ishiwata

Exterior of Sakura Hall
On April 1, 2004, a new lifelong learning facility opened in Kashima Town, Soma-gun, Fukushima Prefecture. The center's main facilities are a 500-seat hall, a library and an Information Technology Training Room. Kashima Town is a town of 13,000 people located along the Joban Train Line in the northern part of the Hamadori region of Fukushima Prefecture. In our April 2004 "News & Opinions" (No. 196), we wrote about a new community center in Kashima Town's neighboring town of Haramachi.

This article focuses on Kashima Town's Lifelong Learning Center. The center was built as the new wing of an existing facility, the Kashima Town Farming Community Improvement Center. The original facility and the new addition stand at the top of a small hill that is just about 5 minutes by car from the JR Railroad's Kashima Station.

<< Project Overview >>

Sakura Hall has an end-stage configuration and is designed primarily for use as a concert hall. The Lifelong Learning Center project's architect, chosen from submissions to an open competition, was the local architectural firm of Yamaguchi Architects, Inc. based in Fukushima Prefecture's Koriyama City. Nagata Acoustics performed the acoustical design, related construction administration and post-construction evaluations.

<< Designing Sakura Hall's High Ceiling >>

Nagata Acoustics joined the project after the floor plan for Sakura Hall had already been decided, but before any major decisions had been made concerning the room configuration of the hall. At this stage of the design process, I used computer simulations to determine the hall's optimal shape, within the predetermined footprint, for the client's specified objective of a hall designed primarily for the performance of classical music.

Early sound reflections, which are the sound waves reflected back to a listener during the first 100 milliseconds after a direct sound arrives to the listener, play a critical role in determining the impression that a hall's acoustics make on the listener. Often, when a small-scale hall is being designed, the ceiling height is kept low in balance with the floor plan dimensions of the room. When a hall has a low ceiling, the laws of physics cause the early reflections to reach the audience very quickly. In this kind of situation, the early reflections of faster-traveling sound tend to predominate, and the result is that it is difficult to produce acoustics with a spacious feeling and more likely that the sound will be unpleasantly noisy.

A low ceiling also necessarily limits a hall's spatial room volume, and the small spatial volume in turn forces the room's reverberation time to be short. But constructing a hall with a high ceiling increases overall building costs and, therefore, is surely not an easy solution when there are budget constraints. For the Sakura Hall project, which had a total budget under 700 million yen (US$6 million; 5 million Euro), the portion of the budget spent to implement a high ceiling was probably the single most lavish expense of the entire project, enabling us to achieve an average ceiling height of 11 m. (36 ft) (from stage floor to hall ceiling) and a total spatial volume of 6,600 cu. m. (233 thousand sq. ft), or about 13 cu. m. (459 cu. ft) of air space per audience seat.

<< The Sakura Hall Interior >>

Sakura Hall's interior makes abundant use of wood and natural color tones, creating a calm and relaxed atmosphere. To promote sound diffusion, we specified that the walls be designed with surface variations and we also installed thin ribbing at the lower wall surfaces near the audience seating. In addition, we installed some absorbing surface areas in sections of the walls and ceiling, both to enable controlled sound absorption and to further promote sound diffusion.

While the hall's primary objective is to be a venue for classical music performances, our room acoustical design took into consideration the fact that Sakura Hall is Kashima Town's only hall and will, therefore, surely be used for lectures and other events as well as for classical music concerts. We accommodated the need to adjust the reverberation time for non-music programs by designing the lower portions of the stage's side walls to rotate open and closed, thereby changing the hall's reverberation time. With the side wall panels entirely closed, the hall's reverberation time measures 1.4 seconds (at 500 Hz, in a fully occupied hall), and with the side wall panels rotated to their open position, the reverberation time can be shortened by 0.2 seconds.

Because Sakura Hall will be used for non-concert events as well as for the performance of classical music, we intentionally restrained the reverberation time from being very long. Nevertheless, when music is played in the hall, the hall and its acoustics give the impression of a longer reverberation and a richer sound than one would expect from the measured reverberation.
View from the audience area @ Interior of Sakura Hall
<< Sakura Hall on TV and the Hall's Future >>

In the first month since Sakura Hall's opening, the hall has already been used as the on-location venue for an NHK (Japan Broadcasting Corporation)TV network program attended by a live audience. The hall's 500-seat audience capacity is quite convenient size. I look forward to hearing about the classical music programming such as piano recitals and performances by school choruses, that the people of Kashima Town will now have the chance to enjoy in this hall built to serve their own local community.

Plan of Kashima Town Lifelong Learning Center

Two Professional Association Meetings in Japan: ICA 2004 and RADS 2004

by Dr. Keiji Oguchi

In April 2004, the 18th International Congress on Acoustics (ICA) and the International Symposium on Room Acoustics: Design and Science 2004 (RADS 2004) both took place, one after the other, in the Kansai region of Japan. The ICA gathering meets every three years in one of the world's major cities, and this year's Congress was held in Kyoto, from April 4 -9, at the Kyoto International Conference Hall. The Congress' return to Japan comes after a 36-year gap since 1968 when the sixth Congress met in Tokyo.

<< Nagata Acoustics' Representation at ICA 2004 >>

Three Nagata Acoustics' engineers attended ICA 2004 and presented papers. Ms. Toshiko Fukuchi, who currently chairs the Architectural Institute of Japan's Research Committee on School Buildings, presented the paper "Guidelines on Acoustic Treatments for School Buildings Proposed by the Architectural Institute of Japan."

Mr. Yasuhisa Toyota presented the paper "Acoustical Design of Walt Disney Concert Hall" about the new home of the Los Angeles Philharmonic in downtown Los Angeles, California. Nagata Acoustics served as the acoustical consulting firm on the Disney project and Mr. Toyota was the project's Chief Acoustician.

In addition, I presented the paper "Perforated Panel - Porous Material Broad-band Absorption System with Screen Strips." The paper discusses some of my doctoral research into the acoustical absorption properties of panels with varying perforation patterns.

<< Attendance at ICA 2004 >>

ICA reported that 1,200 people registered for its 18th Congress in Kyoto, and the Congress program included 13 sessions, the largest number of sessions that ICA has ever held at one meeting. However, for some reason, perhaps the large size of the Congress venue, or because the meeting coincided with the height of the cherry blossom season in full bloom outside, attendance at the proceedings seemed rather sparse.

<< RADS 2004 >>

ICA 2004 ended on a Friday, and was followed the very next Sunday by the start of the International Symposium on Room Acoustics: Design and Science 2004 (RADS 2004), a Satellite Symposium of ICA 2004. For this symposium, we changed venues to the Awaji Yumebutai International Conference Center. Japanese architect Tadao Ando designed this resort-style conference center complex, which is located on a small, picturesque island off the coast of Japan's main Honshu Island.

The format of the RADS 2004 Symposium consisted of oral presentations of invited papers and poster presentations of contributed papers. In addition, I organized a live panel discussion entitled "Recent Developments in Room Acoustical Design Practice," moderated by Rob Metkemeijer of the Netherlands.

<< Session on Recent Developments in Room Acoustical Design Practice >>

In the live panel discussion, acousticians from three U.S., one English and two Japanese acoustical consulting firms, all active in concert hall and opera house acoustics, participated in a lively exchange of knowledge and ideas. The session began with each acoustician presenting an overview of his recent projects and topics of current interest, followed by an open Q&A period. Nagata Acoustics' Yasuhisa Toyota spoke about the difference between shoebox and vineyard configuration concert halls, stimulating discussion on this topic among the panel's other acousticians. Through the opinions and comments expressed by each acoustician and the overviews of their halls, this session gave both participants and the audience insight into the unique and distinguishing characteristics of each acoustical consultant's work.

The invitational papers presented at RADS 2004 included the following topics:

• Computational room acoustics

• Virtual reality, auralisation & sound field control

• Using ISO 3382 measures to assess and interpret conditions in concert halls; and,

• Subjective aspects of room acoustics.

The poster session displayed a total of 63 contributions on a wide range of room acoustical design topics. The three acousticians from Nagata Acoustics who attended the symposium, as well as Nagata Acoustics' Mr. Akira Ono submitted nine poster contributions to the symposium. The topics we discussed in our papers were aspects of some of our recent projects. The symposium organizers collected the papers and presentations into a CD-ROM and the Acoustical Society of Japan also plans to publish the proceedings in a special edition of its English-language journal.

<< New Direction Needed in Room Acoustical Design Research >>

Both the ICA 2004 and RADS 2004 left me with the impression that research on room acoustical design is currently adrift in a stagnant period. In my opinion, this assessment applies equally to research being conducted in Japan and internationally.

Research papers now focus on highly specialized and detailed topics such as one factor of spatial impressions, "listener's envelopment" and how the sound be scattered on boundaries. While these research papers aim to address topics that we should substantially impact our professional work in practical ways, the information we glean from the papers is murky and not something we can use to the immediate benefit of our clients. I would have preferred to hear and read more papers with hint that has concrete and practical applications.

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Nagata Acoustics News 04-05 (No.197)
Issued : May 25, 2004

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