In room acoustics, the directional information of sound arrivals at a listening location can be used to diagnose the origins of problematic reflections so offending surfaces or other features can be properly treated. It can also be used for other purposes, including the study of psychoacoustic indicators. Many methods have been developed in the past to derive directional information, but despite their benefits, each has had significant drawbacks that have necessitated further research into their properties and development of an improved method. This thesis presents a review of past methods, their benefits and shortcomings. It discusses many theoretical and practical issues pertaining to the Polar ETC method and methods using the cross-correlation function. It also presents a new short-time correlation-based method (STCM) for gathering directional information of sound arrivals in rooms. Computer programs were developed for the implementation of the theory. Numerical simulations and experimental measurements are shown and the results are compared to those obtained by the Polar Energy Time Curve (ETC) method. The STCM is shown to be an improvement over past methods in terms of its ability to distinguish between simultaneous arrivals, its accuracy, its computational efficiency and its equipment requirements. Limitations of the method are also discussed.

The properties of acoustic kinetic energy density and total energy density of sound fields in lightly damped enclosures have been explored thoroughly in the literature. Their increased spatial uniformity makes them more favorable measurement quantities for various applications than acoustic potential energy density (or squared pressure), which is most often used. In this dissertation, a new acoustic energy quantity, the generalized acoustic energy density (GED), will be introduced. It is defined by introducing weighting factors, α and 1 − α, in the formulation of total acoustic energy density. With the additional degree of freedom, the GED can conform to the traditional acoustic energy density quantities, or be optimized for different applications. The properties and applications of the GED are explored in this dissertation. For enclosed sound fields, it was found that GED with α = 1/4 is spatially more uniform than the acoustic potential energy density, acoustic kinetic energy density, and the total acoustic energy density, which makes it a more favorable measurement quantity than those traditional acoustic energy density quantities for many indoor measurement applications. For some other applications, such as active noise control in diffuse field, different values of α may be considered superior. The numerical verifications in this research are mainly based on a hybrid modal expansion developed for this work, which combines the free field Green's function and a modal expansion. The enclosed sound field is separated into the direct field and reverberant field, which have been treated together in traditional modal analysis. Studies on a point source in rectangular enclosures show that the hybrid modal expansion converges notably faster than the traditional modal expansions, especially in the region near the source, and introduces much smaller errors with a limited number of modes. The hybrid modal expansion can be easily applied to complex sound sources if the free field responses of the sources are known. Damped boundaries are also considered in this dissertation, and a set of modified modal functions is introduced, which is shown to be suitable for many damped boundary conditions.

Book Summary: Chermak and Musiek's two-volume, award-winning handbooks are back in newly revised editions. Extensively revised and expanded, Volume II provides expanded coverage of rehabilitative and professional issues, detailing intervention strategies for children and adults. Volume I provides comprehensive coverage of the auditory neuroscience and clinical science needed to accurately diagnose the range of developmental and acquired central auditory processing disorders in children, adults, and older adults. Building on the excellence achieved with the best-selling 1st editions which earned the 2007 Speech, Language, and Hearing Book of the Year Award the second editions include contributions from world-renowned authors detailing major advances in auditory neuroscience and cognitive science; diagnosis; best practice intervention strategies in clinical and school settings; as well as emerging and future directions in diagnosis and intervention.

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.

Bei der Überführung eines wissenschaftlichen Laborsystems zur automatischen Spracherkennung in eine reale Anwendung ergeben sich verschiedene praktische Problemstellungen, von denen eine der Verlust an Erkennungsleistung durch umgebende akustische Störungen ist. Im Gegensatz zu additiven Störungen wie Lüfterrauschen o. ä. hat die Wissenschaft bislang die Störung des Raumhalls bei der Spracherkennung nahezu ignoriert. Dabei besitzen, wie in der vorliegenden Dissertation deutlich gezeigt wird, bereits geringfügig hallende Räume einen stark störenden Einfluss auf die Leistungsfähigkeit von Spracherkennern. Mit dem Ziel, die Erkennungsleistung wieder in einen praktisch benutzbaren Bereich zu bringen, nimmt sich die Arbeit dieser Problemstellung an und schlägt Lösungen vor. Der Hintergrund der wissenschaftlichen Aktivitäten ist die Erstellung von funktionsfähigen Sprachbenutzerinterfaces für Gerätesteuerungen im Wohn- und Büroumfeld, wie z.~B. bei der Hausautomation. Aus diesem Grund werden praktische Randbedingungen wie die Restriktionen von embedded Computerplattformen in die Lösungsfindung einbezogen. Die Argumentation beginnt bei der Beschreibung der raumakustischen Umgebung und der Ausbreitung von Schallfeldern in Räumen. Es wird theoretisch gezeigt, dass die Störung eines Sprachsignals durch Hall von zwei Parametern abhängig ist: der Sprecher-Mikrofon-Distanz (SMD) und der Nachhallzeit T60. Um die Abhängigkeit der Erkennungsleistung vom Grad der Hallstörung zu ermitteln, wird eine Anzahl von Erkennungsexperimenten durchgeführt, die den Einfluss von T60 und SMD nachweisen. Weitere Experimente zeigen, dass die Spracherkennung kaum durch hochfrequente Hallanteile beeinträchtigt wird, wohl aber durch tieffrequente. In einer Literaturrecherche wird ein Überblick über den Stand der Technik zu Maßnahmen gegeben, die den störenden Einfluss des Halls unterdrücken bzw. kompensieren können. Jedoch wird auch gezeigt, dass, obwohl bei einigen Maßnahmen von Verbesserungen berichtet wird, keiner der gefundenen Ansätze den o. a. praktischen Einsatzbedingungen genügt. In dieser Arbeit wird die Methode Harmonicity-based Feature Analysis (HFA) vorgeschlagen. Sie basiert auf drei Ideen, die aus den Betrachtungen der vorangehenden Kapitel abgeleitet werden. Experimentelle Ergebnisse weisen die Verbesserung der Erkennungsleistung in halligen Umgebungen nach. Es werden sogar praktisch relevante Erkennungsraten erzielt, wenn die Methode mit verhalltem Training kombiniert wird. Die HFA wird gegen Ansätze aus der Literatur evaluiert, die ebenfalls praktischen Implementierungskriterien genügen. Auch Kombinationen der HFA und einigen dieser Ansätze werden getestet. Im letzten Kapitel werden die beiden Basistechnologien Stimm\-haft-Stimmlos-Entscheidung und Grundfrequenzdetektion umfangreich unter Hallbedingungen getestet, da sie Voraussetzung für die Funktionsfähigkeit der HFA sind. Als Ergebnis wird dargestellt, dass derzeit für beide Technologien kein Verfahren existiert, das unter Hallbedingungen robust arbeitet. Es kann allerdings gezeigt werden, dass die HFA trotz der Unsicherheiten der Verfahren arbeitet und signifikante Steigerungen der Erkennungsleistung erreicht. / Automatic speech recognition (ASR) systems used in real-world indoor scenarios suffer from performance degradation if noise and reverberation conditions differ from the training conditions of the recognizer. This thesis deals with the problem of room reverberation as a cause of distortion in ASR systems. The background of this research is the design of practical command and control applications, such as a voice controlled light switch in rooms or similar applications. Therefore, the design aims to incorporate several restricting working conditions for the recognizer and still achieve a high level of robustness. One of those design restrictions is the minimisation of computational complexity to allow the practical implementation on an embedded processor. One chapter comprehensively describes the room acoustic environment, including the behavior of the sound field in rooms. It addresses the speaker room microphone (SRM) system which is expressed in the time domain as the room impulse response (RIR). The convolution of the RIR with the clean speech signal yields the reverberant signal at the microphone. A thorough analysis proposes that the degree of the distortion caused by reverberation is dependent on two parameters, the reverberation time T60 and the speaker-to-microphone distance (SMD). To evaluate the dependency of the recognition rate on the degree of distortion, a number of experiments has been successfully conducted, confirming the above mentioned dependency of the two parameters, T60 and SMD. Further experiments have shown that ASR is barely affected by high-frequency reverberation, whereas low frequency reverberation has a detrimental effect on the recognition rate. A literature survey concludes that, although several approaches exist which claim significant improvements, none of them fulfils the above mentioned practical implementation criteria. Within this thesis, a new approach entitled 'harmonicity-based feature analysis' (HFA) is proposed. It is based on three ideas that are derived in former chapters. Experimental results prove that HFA is able to enhance the recognition rate in reverberant environments. Even practical applicable results are achieved when HFA is combined with reverberant training. The method is further evaluated against three other approaches from the literature. Also combinations of methods are tested. In a last chapter the two base technologies fundamental frequency (F0) estimation and voiced unvoiced decision (VUD) are evaluated in reverberant environments, since they are necessary to run HFA. This evaluation aims to find one optimal method for each of these technologies. The results show that all F0 estimation methods and also the VUD methods have a strong decreasing performance in reverberant environments. Nevertheless it is shown that HFA is able to deal with uncertainties of these base technologies as such that the recognition performance still improves.

Αυτή η εργασία ασχολείται και αναλύει τα χαρακτηριστικά του συστήματος Controlled Acoustical Bass System (C.A.B.S.), το οποίο είναι ένα σύστημα βελτίωσης της ακουστικής κλειστών χώρων σε χαμηλές συχνότητες, χρησιμοποιώντας πολλαπλά ηχεία και μια τεχνική διόρθωσης βασισμένη στην ανάλυση του ηχητικού πεδίου στο χρόνο. Πριν όμως προχωρήσουμε σε οποιαδήποτε ανάλυση, θα πρέπει πρώτα από όλα να ορίσουμε πιο ακριβώς είναι το πρόβλημα που δημιουργείται στις χαμηλές συχνότητες σε κλειστούς χώρους, καθώς και ποίες μέθοδοι χρησιμοποιούνται για να το αντιμετωπίσουν. / -

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The musician needs to properly perceive the sound in rooms where it operates, either in an environment designed to be performed or to studying and practice music. For this, it is necessary that these sites are acoustically appropriate, enabling the development and enhancement of musical sound perception. In this study six classrooms of the music school of UFSM were characterized by acoustic impulse response measurements and computer simulation, and considered the user s feedback through questionnaires. The questionnaires enabled to understand the preferences of students and music teachers regarding the acoustic quality of a total of twenty rooms for music practice and teaching. Three study rooms and three collective classrooms were the most cited out of those available for the course, which were evaluated by acoustic impulse response, resulting in achieving specified objectives of the main parameters to assess the acoustic quality of rooms by ISO 3382: 2009. The information provided by the musicians proved to be coherent with the measurement data, as the rooms considered dry had presented reverberation times around 0.4 s, and the rooms considered reverberants had reverberation times (RT) around 1.5 s. The six rooms were characterized as clear and well defined rooms, with values for Clarity ranging between 1.0 and 2.0 dB for live rooms and around 22 dB for dry rooms. The definition has remained above 43% for all rooms with Central Time below 50 ms for rooms of greater clarity and less reverberant, and above 90 ms for the live rooms. In general, most rooms were considered weak in relation to acoustic conditioning, and only two out of twenty rooms were considered adequate by most musicians, without receiving considerable negative criticism, being one a study room with a volume of 79.9 m³ and TR equal to 0.4 seconds, and the other a collective classroom with a volume of 327.85 m³ and TR equal to 1.6 s. The computer simulation was efficient for the prediction of the acoustic behavior of the rooms in study and the data obtained in the simulations were compared to the just noticeable difference (JND) for acoustic parameters investigated (T30, EDT, C80, D50 and Ts). A good correlation was observed between measured and simulated data, particularly for parameters related to noise energy in the frequency range from 63 to 8.000 Hz. / O músico necessita perceber adequadamente o som nos recintos onde atua, seja em ambientes destinados à performance, seja em ambientes destinados ao estudo e prática musical. Para que isto seja possível é necessário que estes locais estejam acusticamente adequados, permitindo o desenvolvimento e aprimoramento da percepção sonora musical. No presente trabalho seis salas de aula do curso de graduação em Música da UFSM foram caracterizadas através de medições acústicas da resposta impulso e de simulação computacional, além de considerar a opinião dos usuários mediante questionários. Os questionários aplicados permitiram compreender as preferências dos estudantes e professores de música no que se refere à qualidade acústica de um total de vinte salas para prática e ensino musical. Três salas de estudo e três salas de aula coletiva foram as mais citadas dentre as disponíveis para o curso, as quais foram avaliadas acusticamente através da resposta impulso, resultando na obtenção dos principais parâmetros objetivos especificados para a avaliação da qualidade acústica de salas pela norma ISO 3382: 2009. As informações fornecidas pelos músicos se mostraram coerentes com os dados das medições, de forma que e as salas consideradas secas apresentaram tempos de reverberação (TR) em torno de 0,4 s, e as salas consideradas reverberantes apresentaram tempos de reverberação em torno de 1,5 s. As seis salas se caracterizaram como salas claras e definidas, com valores para Clareza variando entre 1,0 e 2,0 dB para as salas vivas e em torno de 22 dB para as salas secas. A Definição se manteve acima de 43% para todas as salas, com Tempo Central abaixo de 50 ms para salas mais claras e menos reverberantes e acima de 90 ms para as salas mais vivas. Em geral, a maioria das salas apresenta deficiências em relação ao condicionamento acústico, sendo que somente duas das vinte salas foram consideradas adequadas pela maioria dos músicos, sem receber críticas negativas consideráveis, sendo uma sala de estudo com volume de 79,9 m³ e TR igual a 0,4 s, e uma sala de aula coletiva com volume de 327,85 m³ e TR igual a 1,6 s. A simulação computacional se mostrou eficiente para predição do comportamento acústico das salas em questão e os dados obtidos nas simulações foram comparados em relação à diferença no limite do observável (JND) para os parâmetros acústicos investigados (T30, EDT, C80, D50 e Ts). Uma boa correlação foi observada entre dados medidos e simulados, principalmente para os parâmetros relacionados à energia sonora na faixa de frequência de 63 a 8.000 Hz.

This report is guide along simulation of sound sources and orchestra. Basic physical characteristics necessary to the simulation of sound sources are described here. Description of the creation of directivity files in ODEON and theirs conversion from CATT-Acoustic to ODEON are described here too. Acquired directivity files were used for simulation of orchestra and for testing the directivity characteristics to room acoustics parameters.

Detta examensarbete behandlar rumsakustik som en viktig del i skapandet av en arkitektur för framförande av musik, samt upplevelsen av ljud. Projektet bygger på en idé att skapa nya möjligheter att skapa och framföra musik för musiker, vars arbete ofta begränsas av lokalbrist eller av olika föreningars intresseområden. Idén har utvecklats till en hybrid mellan ett nytt musikmuseum och ”Musikplatsen” - en plats för skapande och framförande av musik med liten publik. Musikplatsen blir en del av det nya musikmuseets program för att skapa nya samarbeten och ekonomisk hållbarhet. Projektet är placerat mellan Gröndal och Lövholmen och knyter samman områdenas olika strukturer. Därför spelar detta projekt även en stadsbyggnadsmässig roll som kulturinstitution i en möjlig framtida exploatering av Lövholmens industriområde. I museidelen finns fokus på god utställningsmiljö för olika typer av utställningar i enlighet med övergripande akustiska och arkitektoniska strategier. I projektet finns även en fördjupning inom området rumsakustik vilket har resulterat i särskilt fokus på akustik i designen av byggnadens största rum, - en konsertsalong med 700 platser för akustisk musik. Designprocessen har framskridit på ett kontrollerat sätt via matematiska beräkningar för att nå djupare förståelse inom rumsakustikens komplexitet. / This diploma project investigates room acoustics as a crucial part in developing an architecture for music performance and the experience of sound. The origin of the project comes from an idea to facilitate the constrained work situation of local musicians in the Stockholm region. The idea has been developed into a hybrid between a new music museum and a place for music creation and performance. The project is situated at Lövholmen/Gröndal connecting two totally different areas together along the existing main street. Thus the project also plays a part in a possible future urban development of the industrial area of Lövholmen. The museum parts have focus on interior environment in terms of exhibition spaces for different content, haptic and acoustic experience. Within this project there has been a deep research on room acoustics that has resulted in special focus while designing the largest space, a concert hall for an audience of 700. The design process has proceeded in a controlled way along with mathematical calculations to create a final design on a controlled basis to gain deeper understanding of fundamental parts in the field of room acoustics.

The purpose with this project is to give insight about the theory behind, and the usage of, membrane absorption. This was done in an effort to reduce a particular acoustical problem regarding a room mode which resonated strongly in my music studio and was causing trouble within the low frequencies. In this essay I go through the history, theory, making-of and results of said absorption technique, and explore the possibilities of it working as a relatively cheap and space efficient solution to problems regarding standing waves. The results were positive considering the low budget. The standing wave decay time was almost halved and the frequency response improved, which proves the capability of this type of absorption.