Yamaha Hall, Part 2: Aiming for Ultimate Acoustics
New, Long-Lasting Acoustical Design
The next challenge the project teams faced was to build the hall so that it would remain state-of-the-art for decades to come. Most contemporary concert halls in Japan are either long-and-narrow shape, “shoebox”, type or else “arena” shape type, with the audience seats surrounding the stage. While the project team could have followed either of these approaches, they wanted to build a hall that would provide a unique and utterly distinctive acoustic experience. For this reason, they set their sights on an entirely new hall design—a design that features height over depth and that focuses on acoustics. The hall shape is ideal for acoustic instruments, and offered the possibility of achieving superlative acoustics unmatched by other halls.
Model Testing and Numerical Acoustic Simulations
Yamaha Hall, located on floors 7 to 9, is a small concert hall with a seating capacity of 333. Because it is small, the walls are fairly close together, creating two big acoustic design challenges: how to get rich reverberation in such limited space, and how to avoid the problem of excessive side wall reflection. The main solution the team arrived at was to increase the height to produce more space above the audience while the shape of the side wall was designed as diffusive. But there are no precedents for this type of design within Japan, and so it became necessary to adopt a trial-and-error approach.
First, the designers used model testing and ran numerical acoustic simulations to investigate side-wall patterns. The simulation approach seemed an ideal way to meet the challenge of coming up with a new hall design, as designers can use computers to test the acoustics of a wide variety of shapes. So the design team embarked on two months of daily trial-and-error testing.
Wave acoustics simulation is a method for predicting wave acoustics phenomena for changing sounds. As the video above shows, the designer can watch the computer screen to see how the waves generated from a sound source change and propagate.
Rich Reverberaion and Clear Sound in a Small Hall…
The design team's goal was to achieve a clarity of sound that is usually not attempted with small halls owing to the proximity of the side walls. Close walls tend to produce loud and rapid lateral reflection of the instrument sounds, resulting in a loss of note contour and clarity. The problem seemed difficult to resolve, since size constraints meant that the walls could not be further separated.
But then the design team investigated the flow of the reflections and set about designing side walls that could control this flow. After many cycles of trial-and-error, they came upon a diagonal-lattice wood-tile design that returned quite gentle reflection.
Design of Side-Wall Wood Tiles, and Acoustic Simulations
The team set up a variety of angled wall tiles. Angles were careful adjusted in accordance with 1/5 scale model experiments, and designed so that most of the sound waves hitting the walls would reflect toward the ceiling, with multiple reflections before returning to audience seats. This design caused reflected sounds to go the “long way around,” holding down the reflection energy levels. The team ultimately designed three tile types; “forward down” tiles, “back up” tiles, and a “peaked” combination of the two (shown in corresponding order below).
The team then had to decide how to best arrange the tiles on the walls. They used acoustic simulation to predict the sound characteristics of the hall under different tile arrangements, and then used an auralization system to hear how actual acoustics would sound in each case. They ran comparison tests of the various arrangements while listening to the sound, until constructing what they felt was the optimal pattern. So while the wood wall tiles are an essential aspect of the appearance and ambiance of the building, they also play an essential role in its acoustics.
The final design preserves the clarity of each instrument sound while providing a rich and balanced reverberation. The figure below shows the actual arrangement of the tiling. The three different tile types have been carefully arranged to produce ideal acoustics.
Rich Reverberation From Above
The ceiling of Yamaha Hall was placed as high as possible, and the side walls themselves are angled slightly upward. The design is such that waves reflect upward not only from the individual tiles but also from the walls themselves, howeer through the overhead space, and reflect down from the ceiling toward the seats in a very balanced manner, achieving the rich reverberation reminiscent of a church.
Application of A.R.E. (Acoustic Resonance Enhancement) Wood-Aging Technology
After designing the side walls, the last step was to design the floor for the stage. Stage design is extremely important, and the flooring material has a large effect on the sound of the performance. A wooden floor, in particular, can be thought of as an extension of the instruments being played.
Designers considered the idea of applying A.R.E. technology to wooden flooring. A.R.E. (Acoustic Resonance Enhancement), a Yamaha technology that artificially ages wood in a short period of time, was developed to treat wood for high-end guitars, violins, and other string instruments. The technique places wood under high-pressure steam, causing rapid aging—so that characteristic changes occur in days rather than years. While it is common knowledge that string instruments produce better sound as they age, Yamaha's A.R.E. technology has made it possible to get a mature sound even from young instruments. A.R.E. brings numerous benefits, including higher output volume, better clarity, and better listening for the performers themselves.
But while A.R.E. had achieved successful results with instruments, the design team did not yet know whether it would deliver the same benefits when used for stage flooring. So the team spread some concrete on our factory floor and built some small stages using different types of processing. They then asked musicians and others to come in and run comparative tests, evaluating the stages built with processed wood against those using traditional flooring (see photo below). Results revealed that the processed wood was surprisingly effective in improving the sound. A.R.E. not only resulted in clearer sounds but also delighted musicians who could now better hear their own output.
It has often been observed that the concert hall itself performs as an instrument. The use of flooring that draws on A.R.E. technology enhances the character of Yamaha Hall and contributes substantially to its sound.
And Finally, Hands-On Adjustment
With the design and construction completed, it is up to the technicians to make the final fine adjustments to the environment. They decide the height of the acoustic reflectors (“clouds” ), the position of the piano, the reverberation adjustment, and more. The people who have built our Yamaha Hall acoustics continue to diligently adjust the many parameters until their own ears are satisfied.
The Power of Yamaha Technology
Yamaha made unsparing efforts in designing the Yamaha Ginza Building, mobilizing our long and deep history of acoustic design together with the latest acoustic technologies and a team of dedicated professionals. Yamaha Hall, in particular, has been gaining attention for delivering a fabulous acoustic experience available nowhere else in Japan.
We overcame many difficulties in designing the hall, and we hope you will come to experience its superlative acoustics.