Comprehensive Study On Church Acoustic Environment Theory

A church is a building used for public Christian worship. In traditional liturgy organ music is emphasized more than preaching. After the Reformation more speaking appears in liturgy and as a result both fullness of music and intelligibility of speech are required in a modern church. In recent years there has been much study and research undertaken on the problem in the West but little in China. How to insure both fullness and intelligibility with the consideration of acoustics, architecture and religion is the main content of this thesis. A church is a materialized form of Christianity and the major elements in liturgy are singing, preaching and praying. In this way acoustics, architecture and religion are interconnected in one system. Acoustic measures taken must be in harmony with architectural art and religious tenets. Based on this viewpoint the thesis started from the evolvement of liturgy and church styles to study the cause, characteristics and evolving rules of church acoustic environment; to find out the interactive mechanism of sound and form out of their commonness. Thus the psychological space pursued in Christianity is mapped out through the integration of acoustic space and architectural space. A traditional church is large in space and complex in construction. The long reverberation time insures fullness of music but leads to poor intelligibility of speech. The argument among Western acoustic specialists focuses on how to set the reverberation time in a modern church. Through a great deal of research on the history and reality of churches home and abroad, the acoustical behavior and psychology of worshipers, the author considers that a modern church still needs a long reverberation time which characterize the church acoustic environment.A long reverberation time is good for expressing emotions but not for preaching. The church acoustic history indicates that with the experience of acoustics in closed spaces the priests in the Middle Ages had to speak slowly under a sound-reflecting canopy to make their speech intelligible. Using modern acoustic theories, architectural materials and equipments acoustic specialists today can analyze sound field and improve the church acoustic environment according to the requirements on reverberation in liturgy. In this thesis the author carefully analyses these countermeasures and follows the development of research on the contradiction of reverberation requirements of music and speech, reflects and questions the measures generally applied in acoustic designing. Through an in-depth study on the key factor that influences sound energy decay early in the formation of sound field – the positions of each early reflection surface and their contribution on sound absorption, this thesis discusses the direct influence that different positions of reflecting surfaces have on speech intelligibility and music fullness. It reveals the contradiction and unity of reverberation time in speech and music, argues the feasibility and necessity of a broken-lined reverberation decay manner (e.g. faster at speed in early reverberation decay and slower in late reverberation decay) in church acoustic design. With theoretical improvement made in traditional reverberation study, this thesis puts forward a simple and synthetic method of church acoustic design, that is, to deal with the early sound field using theories of geometric acoustics to insure speech intelligibility and the late sound field statistical acoustics to insure music fullness. The expected reverberation time is called the effective reverberation time.The effective reverberation time theory is validated through the comparison and analysis on the test results of reverberation time and articulation after replacing the sound-absorbing materials. The author makes computer programs and puts this theory into practice by perfecting quality of sounds in traditional churches and through acoustic designing of modern churches. The testing of acoustic indicatrixes, computer simulation and feedbacks all validates its effecti...