Concert hall design hku source
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CCST9014 Individual Report 3035092870 Chan Ka Hei Concert Hall Design and Loudspeaker System Introduction This report serves to introduce to the read some acoustic considerations in concert hall design and the construction of a loudspeaker system. Concert hall and loudspeakers are the primary infrastructure that enables music to be delivered to the mass public. Therefore, they deserve special attention in order for people to attain maximum enjoyment of music. In this report, concert hall design will be discussed in two aspects: shape and materials. Very often t hese two considerations are entangled, as both t he material choice and shape affects the reverberation of sound waves significantly. Furthermore, loudspeaker systems are crucial to amplify sound in large theatres to deliver equal sound to each audience. Synthesizers and its maneuver will be discussed as to explain how fr equencies are selectively magnified to achieve best acoustic effect. In addition, positions of loudspeakers will also be briefly explained. I hope this text would cover basic elements in concert hall design, and be a tribute for the great architects who built great concert halls for our enjoyment. Shape of concert hall The shape of a concert hall determines the propagation and reflection of sound. It is desired that every audience can receive similar quality of sounds. The sound should be acoustically modified such that it delivers a ‘fullness’ feeling as well as great expressions. To achieve the above aims, architects developed a few concert hall shapes. They are shoebox shape, fan shape and vineyard shape. Also, the shape of the sound reflectors, (i.e. walls and ceiling) are treated with protruding patterns for acoustic reasons, which we shall discuss in greater details in the follow section. Shoebox shape (figure 1) is an old fashion design, yet it is very functional. The concert in this shape is long, narrow and tall, with two parallel sidewalls. The audiences are seated in arrays in front of the performers, who usually are orchestras. Parallel sidewalls in this design are the key acoustic component to its characteristic. Sound propagates and reflects in a way that the audiences receive lateral reflection of sound. Lateral reflection (figure 2) refers to that sound reaches at two ears at different time, as the path to one ear is shorter than the path t o the other. Instead of sound reaching at both ears at the same time from a point source, lateral reflection creates a psychophysical phenomenon that people has a sense of envelopment. This can enhance the nuances we perceive in the music, and increase music dynamics. This design also ensures an even distribution of sound to every seat. With the introduction of anti-parallelism treatment, such as balconies and protruding patterns, standing waves and echoes are effectively eliminated to reduce acoustic flaws. Other designs of concert hall may focus on different aspects. For example, in a fan shape concert hall, the audiences are arranged in arrays of arcs. This can achieve a high capacity of audience, however, since lateral reflection is absent in this design, reverberation time is greatly reduced, and the acoustic quality is compromised. Possibly this kind of concert hall will create echoes as sound reflected from the rear wall may be significantly delayed due to long travelling distance. To slightly alleviate the problem, some architects may adopt the vineyard hall design. This is similar to the fan shape, yet audiences surround the performers, in which an intimate physical relationship between the performer and audience as well as a better sightline is achieved. In addition, large
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CCST9014 Individual Report3035092870 Chan Ka Hei
Concert Hall Design and Loudspeaker System
IntroductionThis report serves to introduce to the read some acoustic considerations in concert halldesign and the construction of a loudspeaker system. Concert hall and loudspeakersare the primary infrastructure that enables music to be delivered to the mass public.Therefore, they deserve special attention in order for people to attain maximumenjoyment of music. In this report, concert hall design will be discussed in two aspects:shape and materials. Very often these two considerations are entangled, as both thematerial choice and shape affects the reverberation of sound waves significantly.Furthermore, loudspeaker systems are crucial to amplify sound in large theatres todeliver equal sound to each audience. Synthesizers and its maneuver will be discussedas to explain how frequencies are selectively magnified to achieve best acoustic effect.
In addition, positions of loudspeakers will also be briefly explained. I hope this textwould cover basic elements in concert hall design, and be a tribute for the greatarchitects who built great concert halls for our enjoyment.
Shape of concert hallThe shape of a concert hall determines the propagation and reflection of sound.
It is desired that every audience can receive similar quality of sounds. The sound shouldbe acoustically modified such that it delivers a ‘fullness’ feeling as well as greatexpressions. To achieve the above aims, architects developed a few concert hallshapes. They are shoebox shape, fan shape and vineyard shape. Also, the shape of thesound reflectors, (i.e. walls and ceiling) are treated with protruding patterns for acousticreasons, which we shall discuss in greater details in the follow section.
Shoebox shape (figure 1) is an old fashion design, yet it is very functional. Theconcert in this shape is long, narrow and tall, with two parallel sidewalls. The audiencesare seated in arrays in front of the performers, who usually are orchestras. Parallelsidewalls in this design are the key acoustic component to its characteristic. Soundpropagates and reflects in a way that the audiences receive lateral reflection of sound.Lateral reflection (figure 2) refers to that sound reaches at two ears at different time, asthe path to one ear is shorter than the path to the other. Instead of sound reaching atboth ears at the same time from a point source, lateral reflection creates apsychophysical phenomenon that people has a sense of envelopment. This can
enhance the nuances we perceive in the music, and increase music dynamics. Thisdesign also ensures an even distribution of sound to every seat. With the introduction ofanti-parallelism treatment, such as balconies and protruding patterns, standing wavesand echoes are effectively eliminated to reduce acoustic flaws.
Other designs of concert hall may focus on different aspects. For example, in afan shape concert hall, the audiences are arranged in arrays of arcs. This can achieve ahigh capacity of audience, however, since lateral reflection is absent in this design,reverberation time is greatly reduced, and the acoustic quality is compromised. Possiblythis kind of concert hall will create echoes as sound reflected from the rear wall may besignificantly delayed due to long travelling distance. To slightly alleviate the problem,some architects may adopt the vineyard hall design. This is similar to the fan shape, yet
audiences surround the performers, in which an intimate physical relationship betweenthe performer and audience as well as a better sightline is achieved. In addition, large
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partial walls are introduced to create lateral reflection in some area. Although theacoustic experience is slightly enhanced by the vineyard hall design compared to thefan shape hall, equally good quality of sound is still not guaranteed.
The ceiling of a concert hall always serves as a sound reflector, and they servesfor importance purposes such as to distribute sound equally to all seats, build sense of
envelopment and increase reverberation time. Some very notable design elements arepresent in order to achieve maximum acoustic experience. First, it is the shape orceiling. A concave shape (figure 3) of ceiling would focus the sound emitted from thestage, so architects always avoid it. Instead, fragmented reflection (figure 4) is oftenintroduced to create scattered diffusion to a variation of directions, which would providea uniform sound field. Since there may be a long distance between the audience andthe performer, so the reflection from the ceiling itself may not be sufficient. A suspendedreflector (figure 5) will be then installed in the hall to reduce the sound travellingdistance to increase the amplitude of sound reaching the back of the hall.
figure 1 Stadthalle Wuppertal (a shoebox shaped concert hall)
figure 2 lateral reflection figure 4 fragmented reflection
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The seats and carpets are soft in nature, and inevitablythey absorb a great amount of sound. To alleviate theproblem, empty-seat sound absorption are designed tomatch with the one of seated-seat, this create a morenatural and invariant reverberation.
figure 6 Noise Criterion
Loudspeaker system
Apart from those architectural factors that mainlyaffect the acoustic effect of a concert hall, there aresometimes, when sound amplification must be done inelectronic way. Therefore, a loudspeaker system is also agreat concern in concert hall design. There are three
parts of the system: sound detection, signal processing, and sound propagation. For the
detection, there are usually different microphones to handle. However, there might be aproblem of collecting sounds from the loudspeaker itself, which will create unwantedechoes. To completely solve this problem, an equalizer is used in the signal processingstage. Basically the equalizer can break down the sound wave into different simpleparts of different frequency range. And then each frequency range is amplified ordiminished to suit the purpose. For example, if the performer is a singer, then theequalizer can boost the human voice while diminishes other noise. The last part of aloudspeaker system is the amplification of sounds. A number of speakers is positionedin a way that the sound is diffused naturally to the audience, and often this is alreadyconsidered in the concert hall design. For an example, if a stereo effect is desired, atleast two speakers will be positioned in the sidewalls while a speaker will sit at thecentral.
Referencehttp://www.acoustics.salford.ac.uk/acoustics_info/concert_hall_acoustics/?content=shape University of Salford Manchester, 5
th Dec 2014
http://www.engineeringtoolbox.com/nc-noise-criterion-d_725.html The EngineeringToolbox, 5th Dec 2014David McCandlesshttp://www.jeacoustics.com/library/pdf/ConSpec_Apr90_Concert_Halls.pdf 14th Nov2014
Yuezhe Zhao, Shuoxian Wu, Acoustical Design for Concert Hall in the Science and ArtCentre of Xiamen University, State Key Laboratory of Subtropical Building Sciences,South China University of Technology, 14
th Nov 2014
Pätynen, Jukka, et al. "Concert halls with strong lateral reflections enhance musicaldynamics." Proceedings of the National Academy of Sciences 111.12 (2014): 4409-4414.
