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

Nagata Acoustics News 05-03 (No.207)
Issued : March 25, 2005

A Two-Day, Multidisciplinary "Basic Training" Seminar for Stagecraft Professionals

by Motoo Komoda

On January 24 and 25, 2005, I attended a Multidisciplinary "Basic Training" Seminar for Stagecraft Professionals hosted by the Japan Council of Performers' Organizations ("Geidankyo") in association with other organizations. The seminar participants included a broad spectrum of individuals engaged in the hands-on aspects of stagecraft, plus student observers and observers from other performing arts-related professions. The location of the training seminar was the New National Theater's Playhouse, in the Hatsudai section of Tokyo.

The staging of a large-scale performance work requires the cooperation of many professionals in addition to the creator of the work being performed. Producers, set designers and builders, directors, stage artists, lighting specialists, sound directors and stage managers are some of the many technicians, specialists and artists who must also contribute their skills and creativity for the performance to be a success.

<< The Training Seminar's Goal, Theme and Format >>

An objective of this training seminar was to bring together individuals from a diverse range of specialties and provide them with an opportunity to learn with and from one another. The seminar marked the first time that Geidankyo tried a pan-professional, multidisciplinary approach in targeting the participants of a training event.

Under the overall event theme of "Creativity," frontline professionals from each of the represented specialties shared the steps or processes they use when creating the performance's stage environment. As the specialists watched and listened to each other, they considered the commonalities they discovered as professionals working together towards a greater whole, and the specialists also gained insight into their own creative processes.

More than 300 persons attended the training seminar, with the professional participants accounting for as many as half of the total number of participants.

<< Introductory Overview of the Venue's Stage Equipment >>

The training seminar began with an introductory overview of the Playhouse's sound, lighting and stage equipment and functionalities by the Stagecraft Department of the theater. Regarding the theater's acoustics and sound system, the Stagecraft Department began by explaining the drama-performance focus of the Playhouse's architectural acoustical design. Then the theater's sound specialist combined an assortment of sample demonstrations with explanations of the functionalities of the ceiling and sidewall loudspeakers and each of the theater's other pieces of sound system equipment. In a demonstration of the theater's sound effects capabilities, the sound system was used to generate the uncannily realistic sound of a helicopter flying immediately overhead.

The overview of the Playhouse's stage lighting equipment presentation also combined explanations with demonstrations of the theater's state-of-the-art lighting capabilities. In particular, the Playhouse is Japan's first theater to install a domestically manufactured lighting control console that can generate cross-fades and can use cue lights sequentially to produce chase lighting. The theater's lighting functionalities also include the ability to throw profile spotlights and produce special lighting effects using zoom, "cutter" lighting and focusing.

In addition to demonstrations of the sound system and lighting equipment, the participants were treated to examples of the theater's full-range of moving parts, including a sliding stage, a trap door with a rising platform, a stage floor turntable and overhead batons that can be raised and lowered. The demonstrations of the theater's equipment made it very easy to understand the explanations provided for each piece of equipment introduced by the theater's staff.

<< Creative Artists' Panel Discussion >>

Panel discussion
During the panel discussion portion of the seminar, ten of Japan's most creative and active stage and performing arts professionals spoke about their work. The panel's speakers represented the following stagecraft professions: theater direction, stage set design, lighting, sound production, and stage management. Within each of these professions, the specific work and expertise varied from artist to artist, as did their work backgrounds and the career experiences that led them to their current work.

In particular, for the profession of stage manager or stage director, the scope and style of what is included in this title's job responsibilities varies from country to country and from theater to theater. In some cases, this professional's responsibilities may include technical stage operations, production or stage set construction, managing the entrances/exits and other flow of people on stage, drama direction or any combination of two or more of these roles.

What most impressed me about the comments of the panelists was their shared desire that people in the stagecraft professions be more than simply technically competent operators of their equipment. They said that they wanted the stagecraft personnel to be passionate and proactive about working together as a team with their counterparts from other stagecraft professions. In order to achieve this teamwork, the panelists agreed that the stagecraft professionals need to be able to communicate with each other and that to build this capability it is important for individual professionals to daily work at honing their sensibility for performing arts creativity.

<< The Creative Work Process of Designing and Building Stage Sets >>

To demonstrate the process of designing and building the stage aspects of a performance, the seminar prepared excerpts from three performance programs, including a play, a dance work and an operatic selection. (I discuss each of the programs separately below.) Each of the performances was a short piece, but the stagecraft artists who participated in the stage preparations and design for each of the performances are all Japan's top talent, known for their creativity and vision. Each performance also had a first-rate, professional director involved during the stage preparations.

In addition to being able to watch the stagecraft professionals prepare the stage for each of the three performances, the seminar participants could simultaneously listen via earphones to real-time, running conversation between the stage director and stagecraft professionals as well as commentaries by other stagecraft artists explaining the activities taking place on stage. These commentaries made this portion of the seminar very interesting.

The sets for each performance needed to be built in short periods of time. As we watched the stagecraft professionals do their work and move about the stage, it was easy to understand how challenging their work is and the high level of skill required. In particular, as difficulties were encountered and changes were needed to the original design plans, these professionals rapidly devised improvised solutions for each problem. The speed and creativity with which they adapted to each situation showed that they are truly professionals in their respective fields.

<< An Excerpt from Playwright Kaoru Morimoto's Play: "Rose" >>

Playwright Morimoto originally wrote this play (entitled "Bara" in Japanese) to be performed as a radio drama, and it represents an example of an orthodox spoken drama. The performance's scene changes required abrupt transitions to different time frames and places, and it seems that the point of this performance was to demonstrate how a single, simple and unchanging stage set can be enhanced to achieve such scene transitions. The stage curtains, lighting and sound effects effectively created the right stage environment for each scene performed.

<< Minoru Suzuki's Contemporary Ballet: "Continuum" >>

The stage for this performance had no set or scenery at all, instead using the stage curtains and lighting changes in a rather minimalist manner. The performance involved four dancers whose movements flowed beautifully, creating a sense of fantasy. For the actual seminar performance of this ballet, the accompanying music was a recording of a Mahler symphony. However, during the stage set-up preparations, the music we heard was a totally different genre's music. The performance's director had thoughtfully switched the music during the stage set-up presentation in order to later inject an element of surprise and novelty into the actual performance.

<< An Excerpt from "Three Penny Opera" >>

Preparation for setting
This performance excerpted seven scenes from the famous "Three Penny Opera," written by Bertolt Brecht and with music composed by Kurt Weill. Four singers performed to the accompaniment of a three-piece band that included a keyboard, drums and a saxophone. As each scene opened, the stage curtains rose higher and higher, until the last scene, when the curtains were undone from the baton holding them and fell to the stage floor. With each change in the height of the curtains' opening, the angle of the stage floor likewise changed to a progressively steeper angle. It is quite a difficult feat to align the timing of the changes to the angle tilt of the stage floor with the finish and start of the singers' vocal performances and the band's music, while also taking into consideration where the singers may be standing.

<< Enjoying the Actual Performances >>

The final event of the seminar provided the opportunity to view the three works as actual performances. Unlike the repetitive rehearsals of each stage transition and the many revisions that we watched during the set preparations, the performances, while short in duration, gave the seminar audience the chance to truly enjoy these works of performing art. Of course, unlike the partial performances we saw during the stage set-ups, the actual performances could not be stopped and redone during the performance. I could sense the heightened focus and tension of the directors and stagecraft personnel as they performed under true "live performance" conditions.

<< The Seminar's Q & A Corner and an Overall Evaluation >>

In the spirit of the seminar's goal of increasing communication, the seminar agenda also included Q & A sessions interspersed between the presentations, panel discussions and performances. Participants asked specific and targeted questions, and many of the answers gave me information that will benefit me in my acoustical consulting work.

If this kind of multidisciplinary discussion can be expanded to include the architectural designers of theater spaces, I think that the communication among all the stakeholders will further improve. I hope that seminars like this multidisciplinary "Basic Training" seminar will continue to be offered in the future.

Geidankyo (the "Japan Council of Performers' Organizations") has a website at http://www.geidankyo.or.jp/07eng/index.html. The organization has offices at Tokyo Opera City Tower, 11th Floor, 3-20-2 Nishishinjuku, Shinjuku-ku, Tokyo 163-1466, Japan. The phone number is +81-3-5353-6600.

Photographs: courtesy of Mr. Yoichi Tanuma.

Thoughts on the Acoustical Design of Home Theaters - Part III

by Makoto Ino

In the first two articles of this three-part series, I provided an overview of our acoustical design approach for Mr. K's home theater, and I discussed the selection and placement of the AV equipment installed in the room. In this third and final article, I will trace the development of my understanding of the role of standing waves in the acoustical design of small spaces, then I will conclude with a detailed discussion of the room acoustics of Mr. K's home theater and the interior materials we used to implement the acoustical design.

<< Standing Waves and the Role of Loudspeaker Placement >>

Previously, I mentioned standing waves' possible negative impact on a room's acoustics, a concern that increases if a room's dimensions become squarer than rectangular. Now, let's turn to the relationship between standing waves and loudspeaker placement.

In 2001, I benefited from an opportunity to perform some trial-and-error loudspeaker placement experiments in the audio listening room of Shogakukan, a major Japanese publishing firm headquartered in Tokyo. Nagata Acoustics had designed the Shogakukan audio listening room, and the editor of the publisher's audiophile magazine, "Sound Pal," invited me to work with the magazine's editorial staff on some audio equipment comparisons and loudspeaker placement options in connection with a feature article on these topics.

I worked with the "Sound Pal" staff, using the standard trial-and-error technique of listening to a music CD while incrementally shifting the placement of the loudspeakers to find the locations that would produce the clearest sound with the best frequency balance and least distortion. During this exercise, I was struck by the realization that the changes in acoustical quality obtained by shifting the loudspeakers' placement was caused less by the specific characteristics of the different loudspeakers than by the acoustical characteristics of the room in which we performed the placement experiments.

The Shogakukan audio listening room where we did these experiments promotes sound diffusion via the accordion-like folds of its walls and ceiling surfaces. The appropriate levels of sound absorption are achieved through a combination of glass-wool-backed perforated panels installed in a dispersed manner on the room's interior surfaces and floor-to-ceiling curtains that can be drawn across any portion of the room's four walls. Overall, the room can be classified as close to an acoustically dead space, making it a good environment in which to listen and compare different brands and models of audio equipment.

Based on the results of the experiments with the "Sound Pal" editors, my concern was as follows. The audio listening room's acoustics were specifically designed as a nearly acoustically dead space so that listeners could compare and evaluate the sound of audio equipment without being influenced by the room's acoustics. Why, then, did changing the placement of the loudspeakers in the room affect the sound quality of the loudspeakers heard by the human ear? I decided to further confirm that the location in the room of the loudspeakers affected the sound quality. I used a simple, portable, battery-operated CD/MiniDisc player. I listened to the portable player as it played a CD, and then I repeated the listening experiment at various locations in the room. I could clearly distinguish between locations where the sound quality was good and where it was less favorable. I performed this test with other people in the room and all of the participants agreed on the good sound-quality locations for the loudspeaker of the portable player, regardless of where each person stood in the room or in relation to the loudspeaker.

Since the location of the listener did not affect the outcome, it dawned on me that the room's standing waves must be the determining factor of the variation in the loudspeaker's sound quality. The area where the loudspeaker sounded best was comparatively limited, forming what can perhaps best be described as the acoustical "sweet spot." Since the acoustical sweet spot remains the same regardless of the loudspeaker unit, a room's acoustical sweet spot can be found using a lightweight, portable piece of equipment in place of the heavier loudspeakers that might be intended for installation in the space. Through this experience, I learned both the important role of standing waves in relation to loudspeaker sound quality and a handy method for determining loudspeaker placement in a room.

<< Accounting for Standing Waves in a Small Room Acoustical Design >>

From my experience in the Shogakukan audio listening room, I learned that for the acoustical design of small rooms, sufficient sound diffusion cannot be achieved solely by creating 30, 60 or even 90 cm.-wide (1, 2 or 3 ft-wide) accordion folds and/or protruding design elements along the wall surfaces. Based on this finding, I relied primarily on the room proportions discussed previously, in Part 2 of this article series, to account for the role of standing waves in the sound quality of Mr. K's home theater. Additionally, as I mentioned in my first article, I decided to lean the two sidewalls of the home theater outward and I gave the entire ceiling one, continuous, convex-curved shape. One goal of the angled sidewalls is enhanced sound diffusion of low frequency sounds. In addition, the angled walls minimize the possibility of flutter echoes, enabling me to both reduce the needed sound absorbing structures in the room and (consequently) increase the room's reverberation. In selecting this approach, I took into account Mr. K's musical preferences of opera and jazz vocals and aimed to achieve clear sound reproduction and a lively reverberation characteristic appropriate to these music genres.

<< Building Materials Used in the Interior of Mr. K's Home Theater >>

Fig.1 Reverberation Time
For the interior finishes of Mr. K's home theater, we used the materials and thicknesses shown in the accompanying Interior Materials list. The primary material we used was gypsum board. For the front and sidewalls of the room, we used a combined thickness of 33.5 mm. (1.32 in.), which is the same standard thickness now used in auditorium interiors. For the ceiling, we used a slightly thinner, 28.5 mm. (1.12 in.)-thick combination of gypsum boards in order to build the curve to our acoustical design specifications. For the lower portion of the home theater's rear wall, we installed wooden ribbed paneling of varied width and depth from a few millimeters to 10 mm. (0.4 in.) over gypsum board, for a total thickness of 37 mm. (1.5 in.). The ribs of the wood paneling have random spacing (pitch). Nearly half of the upper portion of the rear wall has perforated gypsum board paneling backed by mineral wool, forming a dispersed pattern of sound absorbing surfaces. On two sides of the curved ceiling there are 1 m. (39 in.)-wide louvers (one opening to a skylight and one designed to be a symmetrical accompaniment to the skylight). The backs of the louver blades are flat and we covered these flat surfaces with gypsum board overlaid with mineral board acoustical panels to prevent flutter echoes.

<< Reverberation Time of Mr. K's Home Theater >>

The reverberation time of Mr. K's home theater is shown by the solid line along the top of the graph in Fig. 1. The results displayed in the graph represent calculated values of the room in an empty state, before the addition of furniture and AV equipment. At 500 Hz, the room's reverberation time is slightly longer than one second, and the high frequencies also reach about 0.9 seconds, reverberation times on a par with the average contemporary small hall. The room's average sound absorption coefficient is in the range of 0.1 - 0.12, regardless of the sound frequency. This sound absorption coefficient is quite low, and I am glad that I obtained this calculation after the completion of the room's interior construction. Had I been able to verify the low sound absorption during construction and prior to confirming the other sound characteristics of the room, I would likely have opted to add sound absorbing surfaces to the room. If I would had added more sound absorbing surfaces, I might have taken some risk out of my design, but the result would have been a less dynamic, more ordinary-quality room similar to the audio listening rooms of previous decades.

<< Mr. K's Home Theater Compared to Other Residential Spaces >>

For comparison purposes, Fig. 1 also shows the recommended reverberation time of the proposed IEC-29B standard, which is based on the acoustics of typical rooms in American and European residences. Below the proposed IEC-29B standard, I show the reverberation range of a traditional Japanese six-tatami-mats room (estimate provided by Dr. Nagata).

The reverberation time of a traditional Japanese tatami-mat room, with its papered sliding doors and woven-mat flooring, measures just 0.2 or 0.3 seconds, a low reverberation time that offers a hint at the sound environment of the traditional Japanese home of bygone times. Regardless of how each of us might evaluate the benefits or downsides of living in an acoustically lively environment, it seems safe to conclude that long reverberation times in a home setting may still be considered something of a novelty by some Japanese.

<< A Summary of the Listening Experience in Mr. K's Home Theater >>

After the addition of furniture and installation of the AV equipment in Mr. K's home theater, we listened to classical music and some old jazz vocals with between one and five people in the room. There was absolutely no impression of the reverberation time being too long. Mr. K also plans to play DVDs of operas with 5.1 channel surround sound, and the home theater's reverberation time will help create the same kind of immediacy and presence experienced in an opera house.

As an experiment, I tried listening to some rock music and other loud-volume popular music in Mr. K's home theater. As I increased the sound volume, the sound diffusion and longer reverberation time created an enveloping sound experience at the expense of some lost clarity. Nevertheless, this home theater amply satisfies the client's request to be able to enjoy both the sound of a rich reverberation time and hear the subtle nuances of operatic vocals and other classical music and jazz in a relaxing and user-friendly environment. I also confirmed that Mr. K's home theater excellently handles a wide dynamic range of vocal performances without any glitches or collapse.

<< Series Afterword >>

This article ends my series on Mr. K's home theater. In these three articles, I have tried to focus both on the acoustical room design of a small space, and on the organic, integrated relationship between the room's acoustics and the sound system equipment. In addition, as I pursued this project and these retrospective articles, I have repeatedly felt the need for the acoustical consulting profession to develop a more robust methodology for the acoustical room design of home theaters. There were multiple experimental aspects to the acoustical design approach implemented in this project, and I am grateful both to Mr. K and to the project architect, Mr. Kenichi Nakamura, for their deep understanding and support during every phase of the project.

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Nagata Acoustics News 05-03 (No.207)
Issued : March 25, 2005

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