Shun Mook Trend(design philosophy)
Acoustic design of a concert hall has been called an art rather than a science. This indicates that it is almost impossible to reproduce the acoustics of Grossermusik Verreinsaal or Boston Symphony Hall by manipulating only a few objective design parameters.
Among lots of feasibilities, manybody interactions and nonlinear phenomena are the major causes of the difficulties of reproducibility of concert hall acoustics.
Sound would be dull if the acoustical phenomena were linear. While linearity beauties theory, nonlinearity gives excitement. Since we are living in the nonlinear world, acoustics gives us fascinations and difficulties at the same time.
After Dr. Sabin's pioneering work on the reverberation, lots of objective parameters have been proposed for both evaluation and design of a room acoustics. Early decay time, Apparent source width, index of loudness, sound diffusion index, initial time delay gap and bass ratio are known to be the major objective parameters and are generally accepted for independent design parameters for concert hall acoustics or a spaces where high quality acoustics are required.
Computer simulation techniques now have been achieved a certain sophistication and concert hall model have proved valuable as consultancy and design.
However, optimization through computer simulation does not guarantee the excellence of acoustics. Apart from the accuracy for the modeling for simulation, there are numerous approximations which cannot be ignored. Of all things, the objective design parameters are merely statistical ensemble averaged(phenomenological and macroscoptic) quantities.
We believe artistic treatment beyond the technology should be needed to make a higher level of concert hall acoustics. But it does not mean we disregard the importance of the technology for the objective performance of a concert hall.
Whenever the frequency of some external source closely matched a natural mode on which it acts, results in resonance. Each natural mode simply has its own resonance response, peaked at its own characteristic frequency.
The combination of natural woods of our MD which flatten the resonance peaks results in neutralization is really impressive. The inlaid structure of two different woods with specific grain orientation of MD which controls the direction of sound forwarding is another useful feature for room acoustics.
More than anything else, MD has a function of pseudo acoustic diffuser which is very useful to improve the diffusivty of a hall where conventional acoustic diffusers are limited due to installation problems.
MD directly integrates the function of nonlinear acoustic characteristics into any materials of walls, ceiling and floor, even the sound sources like speaker system.
The travelling wave originating from the sound source generates standing wave between the surrounding walls. These standing waves impede the uniformity of the frequency response in the room and influences decay of sound.
Since AR has carefully designed Helmholtz resonators whose resonant frequencies overlap enough, the sound of all frequencies is similarly enhanced so that the AR responds well any frequencies to the sound source.
AR consists of 3-5 different resonant cavities and opening holes, which flattens the room resonance up to 6 octave bands by the smooth resonance characteristics. Each chamber has its own resonant spectrum which is determined mainly by the cavity volume and the size of opening hole.
To get the maximum smoothness of AR's resonance, the body of AR is composed of a number of different woods which have their own spectral resonance characteristics. In addition, a number of MDs are installed on the front panel of each chamber which function as a booster of the incoming sound, result in enhancing the efficiency of AR.
In order not to lose diffusion efficiency for the case of large area diffusion by periodic array of simple diffusers, Natural diffuser is composed of unit diffusers with the specific sequences based on the modulation of existing simple diffusion pattern.
The same technique of wood combination as the AR's is applied to build the Natural diffuser, which gives musical reverberant sound as well as the neutralness.
Built-in tunable Helmholtz resonators for controls the resonant frequencies of the lower pitched sounds so that the distortion of the frequency response in the room decreases.
Shun Mook acoustics in chamber music hall(Susong Artpia)
General description and problem statements
-Susong Artpia is a medium sized single purpose hall especially for chamber music
-It is rectangular in shape which is the most likely geometry for good acoustics mainly due to the preferable lateral reflections.
-however, it has low ceiling height (20 feet) suitable for chamber and orchestral music. It is generally recommended that the ceiling height for orchestral music be greater than 35feet.
Shun Mook treatment
From a musician's point of view, little longer rerverberation time is more attractive, and would not be at all for a church. With a properly designed sound reinforcement system and careful planning to make the most effective use of early reflections, this much reverberation is not compatible with good intelligibility
In terms of acoustic function, Susong Artpia is divided into 3 zones, the first 1/3, the second 1/3 and the third 1/3 of this hall are mainly for reflection, reflection+diffusion and diffusrion+absorption respectively.
In order to maintain the proper bass response in the hall, heavy core materials of ceiling and the side wall of the reflection zone are used.
To extend the ceiling height acoustically, MDs and acoustic diffusers are installed on the ceiling.
To make the dense reflected sound and to eliminate flutter distortion, the combination of strip diffuser and AR unit is installed on the side wall.
The combination of the diffuser and AR units at the rear wall eliminates specular reflection and makes the back scattered energy is spread out uniformly spatially and temporally, results in rich, full reverberant sound.
Most of all the inside surfaces are covered with solid woods which can similarly enhance the incident sound so that the surfaces responds well at any frequency to the stimuli it receives from the entire hall.
Shun Mook Acoustics in multi-purpose hall (Hallelujah church)
General description and problem statements
- Hallelujah church is one of the biggest church in the world(over one million cubic feet in volume and over 4,000 seats)
-The church is huge oval in shape which symbolizes Noah's ark so that the echo is easily occurred by the concentration of reflected sound
-The acoustic response characteristics of Hallelujah church are not fully compatible with the needs of the orchestral and choral music, congregational singing and spoken word. Architectural modification cannot adequately address these needs while maintaining flexibility.
In addition, the large interior volume of the facility and deep under balcony preclude the sense of intimacy desired for a house of worship.
Consequently, an electro-acoustical enhancement system providing both early and late energy is required
Shun Mook treatment
The success of a certain hall does not depend on the reverberation time alone, but also on its shape, size, the materials of the enclosure.
However, it is critical that the mid-band reverberation time is less than 1.4 seconds and nearly flat bass ratio which provides comfortable design margin to achieve the desired range for the case of Hallelujah church(multi purpose hall).
diffuser and pseudo diffuser
Damaging naturalness which lots of musicians pointed out is a disadvantage of electro acoustical enhancement system.
The incident sounds onto the ARs, MDs and acoustic diffusers blend together smoothly so that the reflected sound strengthen the direct sound.
In order to reduce the concentration of reflected sound, trigonal prism shaped diffusers with phase grating diffusers and MDs are installed at the side wall.
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