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

Nagata Acoustics News 01-2 (No.158)
Issued : February 25, 2001

"Patio Chiryu," the New Cultural Center in Chiryu City, Aichi Prefecture

by Masaya Uchida

On July 25, 2000, a new cultural center named Patio Chiryu, opened in Chiryu City, Aichi Prefecture. Chiryu City is about a 20-minute express train ride south of Nagoya on the Meitetsu train line. During the Japan's Tokugawa era (1600--1867), Chiryu was a popular way station on the Tokaido Road where Japanese lords with their entourages and other travelers would spend the night at an inn while making pilgrimages to and from Edo (today's Tokyo). During that period of the Chiryu's history, this stop along the Tokaido Road was known by the slightly different name Chirifu, written with Chinese characters that look nothing like the way Chiryu is written today.

<< Chiryu's Famous Bunraku and Karakuri Performance Genres >>

Chiryu's historical heritage thrives today as local artists continue to pursue Japanese traditional puppet performing arts (Bunraku) and mechanical-dolls performing arts (Karakuri). Chiryu Festival, held every two years, is famous for Bunraku and Karakuri performing and its five festival floats, one for each of the town within the city. The festival floats parade through the city streets to Chiryu Shrine, and then Bunraku and Karakuri artists perform on the floats with their puppets and dolls. Several regions of Japan continue to perform and preserve Bunraku and Karakuri, but the Chiryu Festival is the only place where these arts are performed not on a stage of a theater but on festival floats. Chiryu's Bunraku and Karakuri arts are recognized by the Japanese government, which has accorded them the highly-respected status of Intangible Cultural Treasure.

<< Overview of the Patio Chiryu Project >>

The Patio Chiryu Cultural Center project commemorates the 30th anniversary of Chiryu's incorporation as a city. Patio Chiryu's two halls are named after flowers especially associated with Chiryu City. Kakitsubata Hall is the center's large hall, with a seat count of 1,004 seats, and is named after the rabbit-ear iris. Hanashobu Hall is the facility's small hall, with a seat count of 293 seats, and its name means blue-flag iris. In addition to the two halls, Patio Chiryu has a variety of other rooms and facilities, including four rehearsal rooms, a Japanese-style tatami-mat practice room, a crafts studio and other workshop space, a gallery and a restaurant. Nihon Sekkei's Nagoya Branch served as project architect and was also responsible for project management. Nagata Acoustics supported them as the acoustical engineering consultant to the project, with our participation starting during the architectural design phase and continuing throughout all phases of construction and completion.

<< An Architectural Layout Well-deserving of the name "Patio" >>

Patio Chiryu's rooms are grouped around four garden patios, each designed to one of four themes: light; fountain; water; and, greenery. The cultural center's name fits the center's design perfectly and was selected from among suggestions submitted by the general public. In addition to representing the architectural layout of the center, the Patio Chiryu name itself also highlight an important goal of the city residents, that the center be a location where city residents can gather casually and cultural activity will bloom.

<< Kakitsubata Large Hall >>

Kakitsubata Hall is a multi-purpose hall equipped with deployable sliding reflection panels and a coverable orchestra pit, making it an appropriate venue for a wide range of performances and events, such as classical music concerts, opera, plays, conferences and ceremonies. The hall and audience seating arrangement are circular, and the hall has one balcony. For classical music performances, the orchestra pit is covered and this area becomes the front portion of the hall's stage. While some seating is lost in this configuration, the musicians' on-stage set-up is not constrained by the stage proscenium opening and, as a result, the ceiling directly above the musicians is substantially higher than it would be further to the rear of the stage. In addition, the placement of the musicians toward the front of the stage creates a sense of oneness between performers and audience.
Kakitsubata Hall

<< Achieving Fine Acoustics with a Circular Seating Configuration >>

Circular plan is generally avoided in halls that aim for excellent acoustics because of the sound focusing and other acoustical problems likely to occur with this configuration. For Kakitsubata Hall, we prevented the problems that usually come with circular shape by designing wall treatments that make the hall look round to the eye, while the hall's frame is actually constructed to dimensions that make the hall's sides form a more irregular shape. Inside the hall's frame, acoustically permeable ribbing achieves the visual impression of a round hall. We make the angles of the ribbing's front surfaces to alternate their direction and ensure that none of them face towards the center of the hall. By implementing this "slight of hand strategy," we successfully eliminated the need to worry about the particular acoustical problems that occur in true circular halls. In its concert hall configuration, Kakitsubata Hall's reverberation time (at 500 Hz) is 1.8 seconds with the hall empty and 1.5 seconds with the hall full. When the stage curtain is in use, the hall's reverberation time is 1.4 seconds with the hall empty and 1.2 seconds with the hall full.

<< Smaller Hanashobu Hall Suits Both Traditional and Modern Needs >>

Hanashobu Hall is also a multipurpose hall, and in addition to converting to traditional Japanese theater specifications for Bunraku and Karakuri performances, this hall can be equally well used for symposia, conferences and banquets. Hanashobu Hall has removable audience seating, and the floor of the hall's audience seating is partitioned into sections that can be independently raised and lowered to obtain numerous different hall configurations. For example, a portion of the floor can be raised to a height level with the permanent stage to create a seating area for a Bunraku narrator or a thrust stage. Unlike some electronically-controlled floors, the mechanism for changing the height of sections of the Hanashobu Hall's floor uses manually-controlled, motor-driven screws. This system requires somewhat more effort than would electronic controls, but it will be effective majors for the client's budget limitations.

<< Hanashobu Hall's Angled Sliding Reflection Panels >>

The side walls of Hanashobu Hall's stage double as reflection panels that can be deployed for piano recitals and similar musical performances. In order to prevent the reflection panels from causing flutter echoes on stage, each panel is designed to deploy separately so that it can be correctly angled in relation to the audience seating area. Hanashobu Hall's reverberation time (at 500 Hz and with the hall empty) is 1.7 seconds when the hall's floor is flat without seating, 1.4 seconds with the sliding reflection wall deployed and approximately 1 second when the hall uses its stage curtain.
Hanashobu Hall Sliding Reflection Panels
<< Sound Isolation Strategies in a Busy Facility >>

In a cultural center such as Patio Chiryu that has a large variety of functionalities integrated into one space, it is often a challenge to anticipate and plan the sound isolation for each room. Patio Chiryu benefits from the core garden patio in each of the center's four wings. The garden patios create a bright and airy atmosphere throughout the center, and serve as sound isolation for the rooms that surround each patio in a horizontal floor plan. We augmented the sound isolation achieved from the layout of the patios by using expansion joints between the rehearsal rooms and each of the two halls, and we incorporated anti-vibration and sound isolation promoting structural elements into the structural design of medium and small rehearsal rooms. The evaluations we calculated upon the substantial completion of the project confirmed that all of the halls and rehearsal rooms are sufficiently isolated from one another to enable simultaneous use of any or all of Patio Chiryu's facilities.

<< Patio Chiryu's Operational Organization >>

Chiryu City has established the Chiryu Arts and Creativity Council to operate and maintain the new cultural center and former NHK Broadcasting executive producer Seikou Iyoda has been installed as General Manager and Artistic Director. Prior to the center's completion, the city also organized a corps of volunteers, named "Patio Wave," who support the hall by participating in one of five work sections: front office; public relations; event planning and production; stagecraft; and, stage engineering. These efforts indicate the center's strong municipal backing and the community's enthusiasm for Patio Chiryu. Volunteer contributions to the cultural center's newsletter also show active community involvement in the hall. The city's residents clearly feel that Patio Chiryu belongs to them and they actively want to visit and use it. I hope that Patio Chiryu itself will become a blooming cultural core for the entire population of Chiryu.

For more information on Patio Chiryu Cultural Center, contact the Chiryu Arts and Creativity Council at +81-0566-83-8100, or view the center's (mostly Japanese) website at www.city.chiryu.aichi.jp/patio.html.

Understanding Sound Insulation Doors - Specifications and Applications

by Toshiko Fukuchi

In general, the term "sound insulation door" refers to any heavyweight, airtight door. Halls such as concert halls, banquet halls, etc. sometimes have doors constructed of aluminum or wood, but most hall doors are made of steel. Typically, these doors are not sound resistant doors, but rather are made of steel sheeting in the range of 1.6 mm (0.06 in) thickness, have a hollow center, and are each up to around 40 mm (1.6 in) thick.

By contrast, the otherwise hollow centers of sound insulation doors are filled with either glass wool or rock wool and have rubberized gaskets or other material around their frame and, for double doors, along their center edges where the doors meet each other. The glass wool or other filling provides two salutary sound isolation benefits. It increases the door's weight, which we know improves sound isolation performance due to the physical law of the conservation of mass. Secondly, the hollow-center construction prevents the passage of resonance from low register sound waves. In addition, the rubberized gaskets around sound insulation doors and their frames reduce the space between door-leaf edges, making the doors more airtight and ensuring their effectiveness in blocking mid-range and high register sound.

<< More Doors Per Hall Than One Would Think >>

A medium size hall with a seat count of 1,000 seats typically requires in excess of 100 sound insulation doors. Sound insulation doors are used at the entrance to machine rooms to keep the noise therein from being heard in the hall and they are used for the rehearsal rooms' doors to prevent the loud sounds of practicing musicians and others from being heard in other parts of the hall. Likewise, they are used for the entrances and exits to the hall's stage and seating area, where the quietness inside the room must be maintained and extraneous noise kept out.

<< The Mixed Blessing of Added Weight >>

Because sound insulation doors tend to be heavier than regular doors, and also more airtight, they are often also difficult to open and close. I have heard reports of children becoming trapped in-between the two sets of sound insulation doors that separate a concert hall's foyer and the audience seating area. Such unfortunate incidents are no laughing matter for a child and her or his parents, nor for the hall where this occurs. In choosing sound insulation doors, we may need to compromise some degree of ease of use in order to obtain the most desirable sound isolation performance characteristics. Nevertheless, we must also remember that the most fundamental criterion of any door is that it can be opened and closed. The most desirable sound insulation door is both easy to open and shut and has excellent sound isolation characteristics as well. As we aim towards an era of barrier-free spaces, isn't this the kind of sound insulation door that we will want and expect? Below I explore further several sound insulation door topics of recent interest.

<< Correct Hanging of Doors and Sound Isolation Performance >>

As I described at the outset, the relationship between a sound insulation door and its sound isolation performance is correlated to two factors: the sound isolation characteristics pertaining to the door's materials and construction; and whether there are any gaps around the door, these gaps being either between the door and the doorframe or between the abutting edges of two door leaves. It is fair to say that the sound isolation properties of the door itself determine a door's performance with regard to low register sound, while it is the dimensional tolerance of the fit between the gasket and the sound insulation door that determines the door's ability to block mid-range and high register sound. Since the body of the door is a factory-manufactured item, its sound isolation performance on site generally matches the performance ratings in the manufacturer's catalog. However, because the precision of the on-site door-hanging workmanship determines the adjustment of the seal around a door, mid- and high-range sound isolation performance of a sound insulation door may not always attain the ratings listed in the door manufacturer's catalog.

Regardless of whether the door used is sound resistant or not, the most common construction procedure after hanging a door is only to check and adjust the closer mechanism. At numerous job sites, when the construction of a facility is substantially complete and Nagata Acoustics begins the on-site acoustical testing, we find that no adjustments have been attempted on the sound insulation doors. If the rubber door drop botomm of a sound insulation door is properly adjusted, so that it meets the floor without gaps and without buckling, this configuration very effectively improves the airtightness against the flat metal inset on the floor underneath the door's bottom edge. (Tokyoman's Zero Series sound insulation doors are an example of this door construction.) Unfortunately, the percentage of construction sites where this adjustment work is done as a matter of course seems to be extremely low. In my recent experience, this work is never done until I make note of it as part of the post-construction acoustical testing. This oversight occurs even on jobs at which we do advance briefings with the construction engineer in charge on the importance of the door drop botomm's precise fit. It is disappointing to find this valuable gem of functionality so frequently ignored.

<< Ease of Use and Door Sound Isolation Performance >>

At a hall's loading dock and around the stage area, where stage sets and large instruments are carried in and out, doors without thresholds are the most preferred from the perspective of ease of use. In the past, doors with thresholds were used in these locations anyway when the priority was achieving effective sound isolation. However, now that the desired level of sound isolation can be achieved with threshold-less doors such as the one described in the paragraph above (which has a flat metal floor inset and an effective adjustable rubber door drop botomm), sound insulation door selection can take into account a door's location and specific needs for usability.

<< Selecting Sensible Door Hardware for Sound Insulation Doors >>

In achieving the best sound isolation performance, even the choice of the metal latch that closes against the doorframe gasket can make a difference. The preferred part to use is a extension bolt lock. Extension bolt lock ensure adequate airtightness. However, excellent airtightness can make opening and closing doors difficult, leading to unintended consequences. For example, after hall planners spend valuable construction dollars to have a rehearsal room built with vibration isolating structurer that provides a high level of sound isolation, practicing musicians and ensembles may prop open the rehearsal room's sound insulation door throughout the rehearsal because they find the door hard to open and close each time they need to leave the room. I would like to see the availability of lever-type handles that are both easy to use and offer excellent sound isolation performance properties.

<< Easy-to-open, Lightweight Sound Insulation Doors >>

The Japanese door manufacturer Shallentec makes a sound insulation door with a "honeycomb sandwich" construction. This advantage of this product is its light weight and minimum flex compared with sound insulation doors filled with rock wool. In addition, Sharentech uses a rolling latch system that eliminates the need to manually lock its doors. The bottom edges of Sharentech doors are fitted with replaceable and adjustable double rubber door sweeps, and their well-designed thresholds minimize air gaps.

<< Automatic Sound Insulation Doors >>

With the contemporary trend toward unfettered access for all users (known as the "barrier free era" in Japan), we can safely predict increasing installation of automatic sound insulation doors. All of the four Japanese door manufacturers listed at the end of this article offer sliding doors and hinged doors in automatic models. The advantages of automatic doors are that they are easy to open and close, can be made very heavy and can be designed to minimize air gaps, all of which make for excellent sound isolation performance. The automatic sound insulation doors manufactured by the four companies mentioned here each have a sound transmission loss of 35dB in 500Hz or higher. This means that the sound isolation levels achieved with a solid wall can be approximated with a single-layer, automatic sound insulation door.

<< Auditorium Entrance Doors >>

The doors installed at hall entrances have flat thresholds and no astragals. This kind of door usually has air gaps where the door leaves meet as well as between the door and doorframe, further reducing the door's sound isolation performance. Typically, mohair or rubber gaskets are added to the door edges to abate the air gaps. Nagata Acoustics recommends rubber gaskets with sound absorbing specifications. We also recommend using perforated steel backed with glass wool around the doorframe and airtight rubber gaskets to abate the passage of sound through double doors. When sound absorption strategies are not implemented on the doorframe, the sound pressure lebel difference between the sound pressure lebel at the sound source and where the sound is received (in the audience) is often flat for frequencies above 500 Hz and decreases for sounds in the 1,000~2,000 Hz frequency range. However, when sound absorption strategies are implemented around the doorframe, the variance improves. This is an effective approach for improving mid- and high-range sound isolation performance.

In the above paragraphs, I touched on numerous acoustical aspects of sound insulation doors. Since each facility typically requires a large number of sound insulation doors, it may be difficult to focus on the precise details of hanging and adjusting each and every one of them. Nevertheless, I would like for contractors and others involved in this kind of construction work to keep in mind that the installation of sound insulation doors includes not only hanging the door but also the adjustments that are necessary to ensure optimal sound isolation performance.

Some Japanese Sound Insulation Door Manufacturers:
Shallentec Co Ltd.Tel: +81-3-3273-2822
Nippon Sheet Glass Environment Amenity Co. Ltd.Tel: +81-3-5443-0201
Fuso Electric Industrial Co. LtdTel: +81-3-3474-1200
TokyomanTel: +81-3-3496-2991

References used for this article:
"Sound Insulation Doors and Shutteres." in Architectural acoustics and noise control, No. 110. "Trends in Housing Performance Codes: Isolation Around Doors."

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Nagata Acoustics News 01-2(No.158)
Issued : February 25, 2001

Nagata Acoustics Inc.
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