This master thesis examines the effects on the acoustical properties of a concert hall caused by an artificial reverberation system (ARS) and the possibility of simulating these properties. By examining the case of the Stockholm Concert Hall, which recently installed such a system, a greater understanding of the ARS will be gained and additional improvements of simulating such systems will be explored. This study comprises two parts: (1) objective data obtained through acoustical measurements are evaluated both internally and to other halls and (2) by computer simulation of the concert hall and its electronic reverberation system evaluate the acoustics of the hall. The study shows that the effect of the ARS on the acoustical properties of Stockholm Concert Hall is not excessive but noticeable. An 0.3 second increase in reverberation time is a desirable outcome but comes at the cost of clarity, which sees a reduction of 0.7 decibels. Moreover, it is possible to simulate a concert hall, having an ARS installed, with fairly realistic results. However, in order to compile the simulated impulse response, a script had to be created -combining the transfer functions related to each component of the reverberation chain from source to receiver, including all the microphones and loudspeakers of the ARS. / Det här examensarbetet undersöker påverkan på de akustiska egenskaperna hos en konsertlokal orsakad av ett artificiellt efterklangssystem. Likaså undersöks möjligheterna för att simulera dessa akustiska egenskaper. Genom att undersöka Stockholms konserthus, som nyligen installerade ett efterklangssystem, kommer en bättre förståelse för artificiella efterklangssystem skapas och ytterligare förbättringar för simulering kommer att möjliggöras. Den här studien genomförs i två delar: (1) objektiv data, inhämtad från akustiska mätningar, utvärderas både internt och mot andra konsertlokaler samt (2) genom datorsimulering av konsertlokalen och det elektroniska efterklangssystemet utvärderas de akustiska egenskaperna. Studien visar att inverkan på de akustiska egenskaperna hos Stockholms konserthus orsakade av det artificiella efterklangssystemet inte är överdrivna men noterbara. En önskad ökning av efterklangstiden med 0.3 sekunder uppnås men detta på bekostnad av att ljudets klarhet minskar med 0.7 decibel. Vidare är det möjligt att simulera ljudutbredningen i en konsertlokal som har ett efterklangssystem installerat med ett tämligen realistiskt resultat. För att uppnå detta simuleringsresultat skapas ett skript vilket väger samman alla överföringsfunktioner mellan ljudkällan och mottagaren, inklusive de mellan efterklangssystemets mikrofoner och högtalare.

Comprehensive studies are needed to better understand the original acoustical features of historical baths in order to uncover the historical technologies that enabled the acoustical performance for which they are renowned and to ensure they retain this performance with time. In this study, acoustic performances of Seng&uuml / l Hamami and Kadi Hamami, two 15th century historical baths belonging to the Ottoman period, were examined to discover their original acoustical features and to assess their present situation by taking into consideration the recent incompatible repair work. The analyses were done by using 3D computer modeling and acoustical simulation methods supported by laboratory analyses. The results were evaluated in terms of sound absorption characteristics of historical lime-based plasters, the original acoustical features of historical Turkish baths and acoustical failures related to recent repairs. The study showed that these baths had originally well-designed acoustical features provide for a proper environment for musical performances. This success was attributed to the conscious use of historical materials having high sound absorption characteristics. It was seen that these original acoustical features had been destroyed by wrong repairs using cement-based plasters. These plasters demonstrated incompatible acoustical properties, such as less porosity and lower sound absorption coefficients. This study also helped to define acoustical specifications for such historical baths to be maintained in restoration work.

Performance of the buildings has always been a concern for the architects. With the enhancements in the technology, it is possible to measure, analyze and evaluate the performance of an architectural design before it is built via simulation tools developed. With the evaluation of the analysis performance of the concerned space can be upgraded if simulation tools are employed throughout the design process. However, even though the simulation tools are developed for the acoustical simulation and performance analysis, it is not always simple to integrate the simulation tools to whole design process because of both specific knowledge required for the usage of the tools and the nature of the acoustical simulation tools. Within the scope of the thesis, a simulation tool, which does not require advanced knowledge on acoustics and which provides rapid feedbacks about the performance of the design for the enhancement of the performance is developed using method of image sources.

Acoustic design of shopping malls which have become very popular in recent years, has gained importance and it has been considered as an integral part of the design &ndash / construction and life cycle treatment of such complex &ndash / functional buildings. In this study, acoustic qualities of shopping malls are to be inquired by focusing on circulation areas and atrium spaces where noise is one of major disturbances. In this context, first taxonomy of shopping malls regarding their geometrical forms is to be proposed together with plan layouts, construction materials and spatial organizations. Then some of these malls in representing major characteristics of the each class in the taxonomy are to be acoustically analyzed and compared with standards by aiming to provide some guiding principles for acoustical design of such spaces.