The Study On Sound Reflection In Spherical Conformation

While the architect uses spherical conformation to create colorful architectural appearance and indoor space, challenge to acoustics designer of the hall. It is a difficulty in the design of architectural acoustics all the time that spherical conformation creates sound focusing. In April of 1999, my tutor met the question that spherical conformation created sound focusing when he reconstructed the acoustics design of multi-function hall of Wulingye in Yibin. Through analysing, he found that on the condition of incidence of the parallel sound wave different reflection regions make effects on energy focus per area in, at the same time he also made a sequence according ti the influencing degree of sound focusing on the different region. In the dissertation, I introduce this analyse in brief, and name it "energy-area method". On the basis of this method, this dissertation makes further analysis on the sound reflection in spherical conformation. This dissertation also makes accurate conclusion of the sound focusing region, and the increment of sound pressure level in this region.The purpose of this thesis lies in: ascertain the sound focusing region in spherical conformation accurately, the increment of sound pressure level in this region approximately, make a basic principle and method to avoid creating the sound focus for architect and designer of indoor ornament. Therefore it solves reasonably the conflict of spherical conformation between architectural appearance and acoustics design.Have done the following work in the dissertation:①I summarize briefly various kinds of previous methods to avoid the sound focusing in spherical conformation; ②Base on the concave mirror reflection law and energy-area method, I analyse the sound focus in spherical conformation in parallel sound wave incidence, seek the equation of the wrap-up line that is formed by the reflection sound ray, and make ascertain of the sound focusing region accurately.③I achieve approximately the increment of sound level in sound focusing region relative to sound incidence(⊿Lpc), and make ascertain the sound pressure level in focusing region accurately.④Through draw the curve of wrap-up line equation with MATLAB program of computer software. I prove the dependability of the equation in theory; ⑤I design the experiment by myself, use 16 speakers to simulate parallel sound wave, use hemisphere of sky in the laboratory to simulate spherical conformation. In the hemisphere of sky, I measure the mixed sound pressure level. And I also measure the direct sound pressure level on the top of building. Then I can get reflection sound pressure level in hemisphere of sky; ⑥Utilizing reflection sound pressure level to draw the distribution map of sky hemisphere section in different frequency, thus I prove that there is positive connection between the sound focusing area in the spherical conformation and the wrap-up line of the reflection sound ray; ⑦Test ⊿Lpc with some datas of examining points in the floor distance with the high of 2.5 meter and 2.7 meter above the ground; ⑧Through the acoustics design with the top cote of the tennis court in revenue of Chongqing it prove the application of the wrap-up line that is created by reflection sound ray of the spherical conformation.At last the paper achieves some methods and directions about the further study of the sound reflection spherical conformation, and it also puts forward other shape conformation in theory and experiment for the future.