Acoustic Knowledge
        When the acoustic wave encounters wall surfaces(including the ceiling and floor surfaces), the incident wave will be partially absorbed by the wall surfaces, if not rigid type, as the wall surfaces have certain sound absorption capability. The artio of the energy absorbed by the wall surfaces and the incident energy is called the sound absorption coefficient of the wall surfaces. In a diffusion sound field, there is equal chance of sound transmission in all the directions; thus there is equal chance of incident sound in all the directions for all the sound absorption surfaces. Therefore, the sound absorption coefficient shall be the average of all the angles of incidence. If the sound absorption coefficient subject to a sound absorption surface is assumed as “si”, the average indoor sound absorption efficient “a” will be obtained as the total area of sound absorption by averaging the sound absorption coefficients of all the indoor sound absorption surfaces.
Building Acoustics and Electroacoustics
        In hall projects, people are used to decorating the halls following very simple sound absorption concepts as there are merely obscure knowledge on how to achieve good sound effects in their mind. As a result, the expected sound effects pitifully cannot be realized, despite a large amount of investment. Actually, acoustic design for halls along with corresponding treatment measures has long been a highly specialized discipline that cannot be learnt without efforts. People are always misled by the idea that the so-called acoustic design just connects the equipment to give out sound: actually, however, specialized skills and rich engineering experience are required for all of the following purposes: to ensure reliability, practicality, maintainability, coordinated product mix and ingenious system design, to achieve uniformity between the cultural and regional background of the equipment and the business targets, to realize proper sound field distribution, control of electroacoustic technical indicators reliable construction arrangement and noise control, as well as interaction between building acoustics and hall decoration; etc. According to relevant national standards, building acoustic and electroacoustic design must be made for the hall with electroacoustic equipment.