Quietness, Comfortable Sound and Excellent Acoustics NAGATA ACOUSTICS

News 14-05 (No.317)

Issued : May 25, 2014

[ Japanese Version ]

Tiny Concert Hall Now Ready to Open in Seoul, South Korea

By Toshiko Fukuchi

Building Exterior
Building Exterior

In Seoul, the South Korean capital city, a new, 175-seat concert hall completed this spring and is ready to open. The hall is located near Hyehwa Subway Station, which is just a 10-minute ride on the Number 4 Line from Myeongdong Station, one of Seoul's most well-known shopping and business districts in the heart of the city.

<< The Concert Hall's Trendy Neighborhood >>

The area around Hyehwa Station is a popular destination for cultural and performing arts activities as well as shopping. On a site that used to have buildings for Seoul University's Humanities and Sciences Departments a park now serves as exhibition space for many sculptures and other outdoor works of art. In addition, the neighborhood has more than 100 theatres. Readers familiar with Tokyo's Shimokitazawa neighborhood might sense a similarity in atmosphere on Hyehwa streets. Hyehwa Station faces onto a broad street named College Avenue with brand-name stores and designer shops that attract crowds of primarily young professionals. The new concert hall is a short, 5-minute walk from the shops and theatres near Hyehwa Station. Also not far from the concert hall, in a different direction, is a residential neighborhood with historic homes and protective walls like those used for castles and walled cities.

<< The Concert Hall Project's Sponsoring Organization and Nagata Acoustics' Participation >>

The new concert hall was conceived and sponsored by JEI Corporation, a Korean supplementary education company. The concert hall project architect was Tadao Ando Architect & Associates. JEI Corporation's chairman is a fan of Mr. Ando's architectural designs and the chairman directly asked Mr. Ando and his firm to design the two new buildings JEI Corporation planned to build near Hyehwa Station. The concert hall is on the basement level of one of the two new buildings designed by Mr. Ando's firm and built on land directly across the street from JEI Corporation's headquarters.

Nagata Acoustics joined the project at the request of JEI Corporation. Our scope of responsibilities included acoustical room design of the hall, sound isolation design and equipment noise mitigation design, and overall acoustical consulting services from the design phase through completion of the project.

<< Maximizing Ceiling Height in the Acoustical Room Design >>


JEI Corporation first contacted Nagata Acoustics in the autumn of 2010. At that time, the design drawings for the building were already nearly complete. For the building that houses the concert hall, the drawings covered the 4 floors above ground, the hall on the first basement level and a garage below the concert hall. When Nagata Acoustics joined the project, the drawings allowed for a total ceiling height of 13 m (43 ft) on the basement level, but the interior height of the hall stage measured only 7.5 m (25 ft).

We explained to the project team the critical importance of obtaining the maximum possible ceiling height in the concert hall and we dedicated significant time to study and model the expected behavior of early sound reflections in the space while considering options for improving the hall's ceiling height and the shape of the room. As I will discuss again below, the project site is near the Number 4 Line subway tracks, so we knew that we would need to adopt anti-vibration and sound isolation measures in the acoustical design. This requirement would also take up some of the hall location's available space, making it difficult for us to achieve a desirable ceiling height for the hall.

Nevertheless, by slightly increasing the depth of the basement level and designing the stage lighting fixtures to hang from exposed battens, and by implementing other design details, we were able to increase the ceiling height above the stage. The height dimension above the stage now measures 9.5 m (31 ft).

<< Interior Acoustical Room Design of the Hall >>

Given Mr. Ando's proclivity for using exposed concrete, it is no surprise that the two new JEI Corporation buildings use this material for their exterior surfaces. Other buildings in the vicinity also use exposed concrete as their primary exterior building materials. In this environment, the new JEI buildings appear particularly striking and beautiful.

The walls and ceiling of the concert hall have wood finishes, with ribbing detail of random height, width and periodicity. Nagata Acoustics worked closely with Ando Architects & Associates, and with the construction team, to define and implement the ribbing on the walls and ceiling. We also worked closely with these teams on a number of the other aspects of the hall's acoustical room design, such as the angle of incline of the audience seating area's floor and the depth of the stage.

<< Sound Isolation Design >>

JEI Corporation has not yet finalized how the above-ground rooms of the new buildings will be used. To ensure that the upper floors can be used for any desired purpose, we specified anti-vibration and noise isolating structural designs for these rooms so that activities in them will not be affected by performances in the basement concert hall.

We also implemented anti-vibration and sound isolating structural designs to mitigate the transfer of noise and vibration into the hall. Specifically, we used anti-vibration and sound isolation designs:

  • Between the ceiling of the hall and the floor of the street level to prevent the sounds of people walking on the street-level floor from transferring into the hall,
  • Between the hall and the lower level garage that has a mechanical parking system, and
  • Between the hall and the Line 4 subway train tracks located just 55 m (180 ft) from the building site, to mitigate solid-borne noise transfer from passing trains.

In addition, Nagata Acoustics provided advice and recommendations to reduce noise from HVAC equipment in the building's machine room that is situated near the concert hall and noise transfer through ducts and the building's fire sprinkler system. Through the combination of structural design and other sound isolation measures we successfully achieved our "very quiet" quietness criterion goal of better than NC-20.

<< Post Completion Validation of the Concert Hall's Acoustics >>

After the completion of construction, the client invited a violinist to play in the hall so that we might validate the characteristics of the hall's acoustics. In this small, 175-seat hall, the rich and full sound exceeded even my most optimistic expectations and the sound also had excellent clarity. We had achieved the objectives we set for the hall when we joined the project team.

Audience Seating Area
Audience Seating Area

The violinist who performed in the hall for our validation said that before coming to the hall she was told that it is a small space, but when she played in the hall she felt as if she was playing in a large concert hall. She said she wants to continue to play in the hall and experience the same sense of a large hall in the intimacy of a small space. In fact, even after the performance for validation ended, she continued to walk and play her violin while standing at a variety of different places on the stage.

The schedule for formally opening the hall for public concerts still needs to be finalized. Also, ongoing programming and operations of the hall need to be organized. I've been told that youth-oriented programming will surely be part of the concert hall's regular schedule. I look forward to this delightful new concert hall making its mark on the Seoul classical music scene.

JEI Corporation's website is http://us.jeilearning.com/ and the Korean website is http://edu.jei.com.

JATET Publishes V.2 (2014) of Electrical Equipment Guide for Theatre Spaces

By Makoto Ino

Exterior of Tonhalle
Cover Page of the New Guide

In March, 2014, the Electrical Equipment Society of Japan's Theatre and Entertainment Technology Association (JATET) and Institute of Electrical Installation Engineers of Japan published the second version of its Electrical Equipment Guide for Theatre Spaces. This is the first revision since the Guide's original publication 15 years ago, in 1999. The Guide primarily covers the design and installation standards and specifications for stage machinery, stage lighting and stage sound system electrical equipment, especially production communication system and video projection systems. The Guide also covers the electrical power supply equipment and apparatus needed to run the electrical equipment used during events at theatres and concert halls.

I participated in the Guide's revision as the lead representative for the JATET Acoustics Committee. I wrote the updates to Chapter 4, which focuses on sound system equipment design and installation. Given the many years that have elapsed since the Guide's first publication, my edits became mostly a rewrite of the entire chapter.

<< Use of the Guide for Official Purposes >>

Even though the Guide is published by a private-sector industry association, because the Guide's standards and specifications received the approval of the Japan Electrotechnical Standards and Codes Committee(JESC), the Guide complements the governmental "Electrical Equipment Technical Standards Ordinance" and "Electrical Equipment Technical Standards Interpretations" issued by METI (Japan Ministry of Economy, Trade and Industry) to fulfill the aims and objectives of Japan's Electric Utility Industry Law. Therefore, the Guide's standards and specifications can be referenced and quoted to validate that a design or installation complies with the government standards.

For Japan's publicly funded buildings, regional and other governmental administrations have relied on adherence to the Ministry of Land, Infrastructure, Transport and Tourism Secretariat's "Public Works Standards and Specifications Manual", published by the Japan Public Buildings Association. Most public halls, including those in more rural locales, rely on these specifications to achieve consistent quality standards.

However, because the Japan Public Buildings Association manual does not include regulations for stage equipment, in the past, each public project's bid package needed to include detailed specifications for the project's construction standards for desired stage equipment performance goals, equipment selection and installation methods. These detailed stage equipment specifications added voluminous amounts of documentation to each public hall project's bid packages and was a key justification for writing and publishing a Guide that would be considered the standard for all projects. With the publication of the Guide, projects became able to reference its specifications and individual project documentation became limited to specifications for any items that need to differ in design or implementation from the Guide's standards.

The new Guide retains the original version's standards and specifications where they continue to be applicable. From that starting point, the new version addresses recent stagecraft enhancements and the many innovations made possible by technical and product advances. The new version also takes into account related recent legislation and revisions to other industry standards and adapts the information in the Guide to suit the environments in which stage electrical equipment is typically designed and installed today.

When electrically powered stage equipment and apparatus are operated, the fundamental concerns are, first, that operating the equipment not cause physical harm and, second, that the equipment not generate undesirable noise on stage or in other parts of the hall. The original version of the Guide considered safe operation of the electrical equipment to be the highest priority and this prioritization remains the same in Version 2. Each section of the guide includes an overview, performance data and requirements for proper use, technological explanations and design and installation criteria, as well as precautions and applicable warnings. The guide additionally provides standards and specifications for non-electrical stage equipment that is used with the electrical equipment and when installing electrical equipment, such as connectors, surge protectors and grounding equipment. Also, the Guide explains strategies to address other high frequency noises, and safety measures related to these items. To complete the Guide's comprehensive coverage of stage electrical equipment for theatres and halls, the Guide includes an inspection checklist for proper maintenance of stage electrical equipment functionality.

Japan's Theatre and Entertainment Technology Association (JATET) will hold forums in Tokyo and Osaka in July, 2014 to explain the changes in Version 2 of the Guide. For more information visit the Japanese website below:

Acoustical Society of Japan (ASJ) 2014 Spring Conference Special Session Topics

By Fumiaki Sakamaki

The Acoustical Society of Japan (ASJ) held its 3-day, 2014 Spring Conference from March 10 through 12 at the Nihon University College of Science and Technology Ochanomizu campus. The wide-ranging diversity of lectures and poster sessions at the conference amply displayed the many academic sub-disciplines within the field of acoustics. For example, among the more than 600 lectures and poster sessions were topics such as architectural acoustics, noise and vibration, sound systems, phonetics, ultra-high frequency sound and the human auditory system.

In the limited duration of 3 days and with many lectures occurring simultaneously, it was of course impossible to attend all the sessions I wanted to hear. In this brief report I will share some comments on two sessions I attended that were designated as Special Sessions of the event.

<< ASJ Prediction Model 2013 for Road Traffic Noise >>

On the second day of the conference I attended the Special Session lecture on the "ASJ Prediction Model 2013 for Road Traffic Noise" (ASJ-RTN-Model 2013), presented by University of Tokyo Institute of Industrial Science Associate Professor Shinichi Sakamoto and the Road Traffic Noise Research Committee. The ASJ published the 2013 version of the model in April, 2014.

This prediction model is widely used in Japan for environmental assessments of road traffic noise. The ASJ published the first prediction model in 1975 and has published an updated version about every 5 years since then. During the 5 years between the immediately prior version's publication in 2008 and the publication of the 2013 version this year, the researchers measured the sound power level of today's automobiles when they are being operated and studied the difference between today's levels and the levels used for the prediction model in 2008.

The 2013 version takes into account the expected increase in hybrid and electric cars in future years and how this will affect automobile sound power levels. Also, the new version presents the most current information on what improvements can be expected from the 2-layer pavement drainage systems that it is hoped will be implemented in Japan as a strategy to reduce road traffic noise (among other benefits). In addition, the 2013 version adds a calculation method for road traffic noise at interchanges equipped with electronic toll collection systems (ETCS).

<< Outdoor Emergency and Disaster Mass Notification System >>

On the conference's third day, the Special Session delved into the state of outdoor emergency mass notification systems and the ideas and hurdles to improve this method of communication in times of natural disasters. According to the speaker, Tohoku University Professor Yoiti Suzuki, a survey conducted at the request of the Japanese cabinet revealed that during the 2011 Tohoku Earthquake, 52% of survey respondents said that when the disaster struck, they first learned about the tsunami warning from an outdoor wireless emergency broadcast. However, of that 52%, only half said that they heard the contents of the broadcast clearly, while 20% said that they could hear something being broadcast, but could not understand the content of the communication.

Currently, Japan does not have installation and performance standards or guidelines for outdoor public address systems. The design and installations of these systems typically only consider the directionality of the loudspeakers and power output capacity.

In light of the current situation, the Acoustical Society of Japan set up a technical research committee to investigate what recommendations and standards should be put in place for outdoor emergency and disaster mass notification systems in Japan. The committee's goal is to formulate standards for achievable and appropriate performance evaluations of these systems.

Mr. Kiyohiro Kurisu of the electronics manufacturer TOA Corporation spoke about how his company's engineers do acoustical performance measuring and auditory evaluations of outdoor mass notification systems on-site at client locations during system installations. He also described the difficulties and constraints involved. For example, in the out-of-doors, it is difficult to reproduce the sound signal used to measure such physical performance measurements as the level of pink noise. Also, when TOA Corporation employees conduct the tests, instead of the sounds used for a real emergency, they test with a calm-sounding set of tones so that local residents will not mistake the test for an emergency alert. In addition, conducting a test of one of these systems-when there isn't an emergency situation-requires the understanding and cooperation of the residents of the entire area covered by the system. This requires consideration for the communities involved and advance planning.

Outdoor sound amplification is prone to long path echoes caused by reflection from a distant buildings. Also, announcements transmitted and broadcast outdoors can be affected by ambient noises and by weather conditions. The many possible variables make this a complex topic from the acoustical science perspective. In preparing for the use of mass notification systems in case of a future disaster, even small, incremental improvements in the quality and performance of outdoor amplification will surely be beneficial.

Nagata Acoustics Inc.

(Tokyo Office)
Hongo Segawa Bldg. 3F, 2-35-10 Hongo
Bunkyo-ku, Tokyo 113-0033, Japan
Tel: +81-3-5800-2671, Fax: +81-3-5800-2672

(LA Office)
2130 Sawtelle Blvd., Suite 308
Los Angeles, CA 90025, U.S.A.
Tel: +1-310-231-7878, Fax: +1-310-231-7816

(Paris Office)
75, avenue Parmentier
75011 Paris, France
Tel: +33 (0)1 40 21 44 25, Fax: +33 (0)1 40 21 24 00

E-mail: info@nagata.co.jp

[ Japanese Version ]