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Abstract

The thesis is concerned with the modelling of sound fields in large enclosed spaces. Although the subject is necessarily complex, today’s computer systems provide a unique opportunity to develop numerical models for the analysis of acoustic behaviour in such spaces.

Based on the findings of a survey on the modelling of sound fields a computer model is implemented. The model is capable of predicting accurately the acoustic environment of bounded spatial systems of any particular geometry including rooms with curved surfaces. Note that in buildings with curved surfaces there are often serious problems with speech intelligibility and the appreciation of music. The proposed model given the name CADAE (Computer-Aided Design of Acoustical Environments) is developed based on the geometncal acoustics approach and computer programs are written in C++ an object-oriented language and MATLAB, a fourth generation mathematical language. The preprocessing, that is the data input is carried out in the model’s description language, which could be assisted by a computer-aided design package such as Autodesk’s AutoCAD.

The CADAE model is applied successfully to a variety of acoustical environments including rectangular rooms, fitted rooms, long enclosures, rooms with tilted walls, coupled rooms, spaces with curved walls and a very complex case, namely London St. Paul’s Cathedral. The model is validated for various acoustical parameters including Sound Pressure Level, Speech Intelligibility and Reverberation. Further, the significance of using curved surfaces is appreciated by direct comparison to the flat surface approximation. As shown using the exact curved surface model improves the accuracy by up to 90% especially around the focal region.

The computer model presented in this thesis will assist noise control engineers, architects, sound contractors, acousticians etc., to meet the acoustic requirements when designing an enclosure, help in choosing the most appropriate materials, location for the sound source(s), receiver(s) and generally aid m diminishing any acoustical problems. Further, the work presented contributes to the ongoing research of virtual reality and telepresence by approaching the virtual auditory environment.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering > Mechanical Engineering & Aeronautics School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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