The Basic Method Of Classroom's Acoustic Environment Analysis

As known, classroom is an important part of the school constructions. The quality of room acoustic environment affects not only the communication between the teacher and students directly, but also the quality of education. In recent years, more universities paid great attention on the classroom acoustic environment. Meanwhile, they also did some effective and satisfactory improvement for the not-so-effective classrooms by measuring, analyzing and updating. For the better acoustic conditions of Shandong University at Weihai, the author chooses a specific classroom as the experimental target, and writes the thesis on the basis of the measurement, then proposes some suggestions for improving.To improve the acoustic environment of a classroom, the first and most important thing is to analyze the current acoustic conditions, which includes learning the current acoustic conditions and it's defects as well. The second is to put forward an improvement program and run the computer simulations. The next is to compare the results and choose the program and implement the program for real finally. The focus of this thesis is the first step, which means to propose a more practical and economical method through studying various current acoustic analysis methods.When an acoustic source radiates sound in a closed chamber, the soundwaves will radiate to all directions. Some of the soundwaves will be absorbed when they meet the wall, the ceiling and the floor; while others will be reflected and absorbed when they meet the wall, the ceiling, and the floor again. This situation occurs repeatedly, thus forming a very complex room sound field. Starting from Sabine's work in 19th century, the room acoustics has developed very well in more than 100 years. Numerous acousticians have conducted researches on various aspects of hall acoustics in many methods. Although people nowadays have made much more progress on room acoustics than that in 19th century, there are still many aspects of room acoustics that remain unknown.Methods introduced in this thesis include:the proportion-reduced scale model method, the computer sound field simulation method, the fluctuation acoustic method, as well as the electroacoustical measurements. Among them, the computer sound field simulation method is based on the geometric acoustics theory, including ray-tracing method and virtual sound source method. The electroacoustical measurements include two aspects, the sound field measurements and the result analysis. While in sound field measurements, steady interrupted noise method and reverse integration impulse response are included. Through the study on these methods, and the analysis about their advantages and disadvantages, practical and economical update plan is proposed base on electroacoustical measurements of the chosen a classrooms. The time of reverberation is also calculated using Matlab.