Raumakustik - Interaktion visueller und auditiver Wahrnehmungen

Abou-Elleal, Esam Ragab Esmail; Führer, Wilfried (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2003)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2003

Abstract

The subjective impression of space on people is determined by different elements. Important roles are played by architectural elements such as shape, size, colours, lighting and etc. In addition the acoustics can supplement this determination especially at use some types of the spaces, in which speech or music is of interest (e.g. classrooms, lecture rooms, cinema halls, theatre, concert halls, churches and etc.). The aim of the work is to conduct an investigation on improvement of the acoustic properties of rooms in early phases of architectural designs, and as the consequent step to evaluate by experimental investigations the acoustic quality of the spaces, the visual and acoustic agreement and the total impression. Since this work concerns the visual and acoustic impression of the spaces, the foundations of room acoustics are described in order to discuss the propagation of waves in closed spaces and by the effect of the design of the architectural elements. Finally an introduction into psychoacoustics is given, which represents a connection between subjective feelings (human perception) and objectively measurable quantities. To obtain a prediction of the acoustic conditions, computer simulations are used. The acoustic characteristics of some architectural design studies which were created for a mobile swimming theatre by students at the faculty of architecture of Aachen University are improved by different techniques. These techniques are connected with the architectural design, the acoustic properties of the used materials or electro-acoustic installations. To evaluate the degree of the acoustical quality for several speech signals with a theatre performance, to judge the 'match' of the visual impression (closed, semi-closed or opened theatre) with the acoustical impression at the same time, and also to evaluate the overall impression (desired feeling) for all situations, the selected design has been examined by an experiment in an anechoic room. The results based on the answers of the test persons to the questionnaire, are statistically evaluated. A good acoustic quality for a theatre performance (for speech) corresponds to the values of the reverberation time between 0,4 and 1.0 second for middle frequencies. Furthermore a good visual and acoustic agreement is obtained in the closed theatre. In contrast the opened theatre is judged with a large uncertainty. The reason is that most test subjects have more experience with closed than with opened theatres, particularly with speech theatres. Finally for the overall impression the simulated signal representing the closed theatre is preferred with all visual situations, although it does not match visually with the opened theatre. In contrast, the 'dry' acoustic signal was rejected by the test subjects and only partly accepted in combination with the open space.