<p>Steady-state sound fields in enclosures, with specular and diffuse reflection boundaries, are modeled with a first-principle energy-intensity boundary element method using uncorrelated broadband directional sources. The specular reflection field is represented by a limited set of spherical harmonics that are orthogonal on the half-space. The amplitudes of these harmonics are determined by a Lagrange multiplier method to satisfy the energy conservation integral constraint. The computational problem is solved using an iterative relaxation method starting from the 3-D diffuse reflection solution. At each iteration, directivity harmonics are estimated by post-processing and the influence matrix is refined accordingly. For internal sources, simple first reflection images improve accuracy with virtually no penalty on computation time. Monotonic convergence occurs in relatively few relaxation steps. Extrapolating to an infinite number of boundary elements and iterations gives very accurate results. The method is very computationally efficient. Results are compared to exact benchmark solutions obtained from a frequency-by-frequency modal analysis, and a broadband image method, demonstrating high accuracy. The method of absorption scaling is verified for complicated 3-D cases, and showing that the spatial variation in rooms is largely determined by source position and the relative distribution of absorption, but not the overall absorption level.</p> / Dissertation

A well-made flute is always a compromise and the job of flute makers is to achieve a musically and aesthetically satisfying compromise; a task that involves much trial and-error. The practical aim of this thesis is to develop a mathematical model of the flute and a computer program that assists in the flute design process. Many musical qualities of a woodwind instrument may be calculated from the acoustic impedance spectrum of the instrument. A technique for fast and accurate measurement of this quantity is developed. The technique is based on the multiple-microphone technique, and uses resonance-free impedance loads to calibrate the system and spectral shaping to improve the precision at impedance extrema. The impedance spectra of the flute and clarinet are measured over a wide range of fingerings, yielding a comprehensive and accurate database. The impedance properties of single finger holes are measured using a related technique, and fitformulae are derived for the length corrections of closed finger holes for a typical range of hole sizes and lengths. The bore surface of wooden instruments can change over time with playing and this can affect the acoustic impedance, and therefore the playing quality. Such changes in acoustic impedance are explored using wooden test pipes. To account for the effect of a typical player on flute tuning, an empirical correction is determined from the measured tuning of both modern and classical flutes as played by several professional and semi-professional players. By combining the measured impedance database with the player effects and various results in the literature a mathematical model of the input impedance of flutes is developed and implemented in command-line programs written in the software language C. A user-friendly graphical interface is created using the flute impedance model for the purposes of flute acoustical design and analysis. The program calculates the tuning and other acoustical properties for any given geometry. The program is applied to a modern flute and a classical flute. The capabilities and limitations of the software are thereby illustrated and possible contributions of the program to contemporary flute design are explored.

abstract: Traditional consensus in duos with grand piano has been that issues of balance between piano and the other instrument can be corrected through lowering the lid on the piano, particularly when the other instrument has been thought of as less forceful. The perceived result of lowering the lid on the piano is to quiet the piano enough so as not to overwhelm the other instrument, though the physics of the piano and acoustics suggest that it is incorrect to expect this result. Due to the physics of the piano and natural laws such as the conservation of energy, as well as the intricacies of sound propagation, the author hypothesizes that lowering the lid on the piano does not have a significant effect on its sound output for the audience of a musical performance. Experimentation to determine empirically whether the lid has any significant effect on the piano's volume and tone for the audience seating area was undertaken, with equipment to objectively measure volume and tone quality produced by a mechanical set of arms that reproduces an F-major chord with consistent power. The chord was produced with a wooden frame that input consistent energy into the piano, with measurements taken from the audience seating area using a sound pressure level meter and recorded with a Zoom H4N digital recorder for analysis. The results suggested that lowering the lid has a small effect on sound pressure level, but not significant enough to overcome issues of overtone balance or individual pianists’ touch. / Dissertation/Thesis / Doctoral Dissertation Music 2017

Orientador: Stelamaris Rolla Bertoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-12T13:24:21Z (GMT). No. of bitstreams: 1 Rodrigues_CarlosEduardo_M.pdf: 10260499 bytes, checksum: ff857253ca6fab4a0f04bf083de17715 (MD5) Previous issue date: 2008 / Resumo: Estímulos sonoros semelhantes podem gerar diferentes percepções sonoras num ambiente. Os estímulos sonoros são avaliados de forma objetiva (medidas acústicas), mas a percepção do som que é bastante subjetiva requer outro tipo de avaliação. Espaços como ginásios de esportes podem proporcionar ao usuário diferentes sensações sonoras dependendo de sua atividade. Urbanisticamente, os ginásios de esportes são edificações muito importantes, destacando-se na maioria das vezes por sua volumetria e por sua estética arquitetônica, sendo uma obra de referência (símbolo urbano). Desde sua origem histórica, estas edificações têm a função de servir principalmente as atividades e eventos esportivos, mas no final do século XX, a concepção funcional dos ginásios foi ampliada. Os ginásios de esportes são utilizados também para assembléias escolares, palestras, exposições, formaturas, shows, eventos, feiras e apresentações musicais e teatrais, sendo considerados como espaços multifuncionais. Esses espaços são ambientes onde a propagação sonora gera inúmeros problemas de ruído. O objetivo desta pesquisa é caracterizar acusticamente alguns ginásios de esportes, quanto à tipologia, volumetria, capacidade de absorção e isolamento, de forma a contribuir com parâmetros a serem utilizados futuramente em projetos de edificação com qualidade acústica. Foram avaliados três ginásios esportivos multifuncionais com tipologias diferentes situados na cidade de Campinas. A caracterização acústica baseou-se nas medidas dos parâmetros tempo de reverberação (TR), tempo de decaimento inicial (EDT), clareza (C80), definição (D50), nível de critério (NC), índice de transmissão da fala (STI) e porcentagem de consoantes (%ALCons). Esses parâmetros acústicos são obtidos por meio da técnica de resposta impulsiva e calculados pelo programa computacional de avaliação acústica de salas, DIRAC da Bruel & Kjaer. Pelas dimensões do espaço, o próprio procedimento de medição é um fator determinante na avaliação. Os resultados da análise da avaliação acústica e a comparação com as informações do projeto arquitetônico permitiram estabelecer fatores favoráveis e desfavoráveis do projeto arquitetônico que influenciaram o desempenho acústico. Identificou-se também a viabilidade de adequação acústica dos espaços estudados. / Abstract: Similar sonorous stimulus may promote different sound perceptions in the environment. Sonorous stimulus may be objectively evaluated by acoustic measurements however, sound perceptions evaluation (subjectively) requires another specific methods. Spaces like sport gymnasiums can promote different sensations for the users depending on their activities. This type of building is very important in the cities, basically to this size and esthetic. Since the ends of 20th century, the function of these buildings has been extended. Nowadays, gymnasiums are used for different types of meetings, like speeches, expositions, fairs and others. Therefore, sport gymnasiums are multifunctional spaces with different levels of requirements concerning acoustic performance. On the other hand, the sound propagation in these buildings can generate many problems of noise, decreasing the acoustic performance. In this context, this work aims to evaluate some sport gymnasiums concerning to the typology, absorption capacity and isolation. These parameters can be used for better acoustic building design. Basically, the acoustic evaluation contemplates the following parameters: reverberation time (TR), early decay time (EDT), clarity (C80), definition (D50) and speech transmission index (STI). These acoustic parameters were obtained through the impulsive technique and calculated by a room acoustics evaluation software DIRAC from Bruel & Kjaer. The acoustic evaluation results and the architecture design information were used to establish good and bad conditions in terms of the acoustic performance. Finally, the viability of adequacy of the buildings evaluated concerning the acoustic performance was made. / Mestrado / Arquitetura e Construção / Mestre em Engenharia Civil

Orientador: João Antonio Pereira / Resumo: A indústria fonográfica com o advento dos equipamentos digitais de gravação sofreu grandes transformações nos últimos anos. A mudança mais marcante é a migração dos músicos que antes trabalhavam com grandes gravadoras e hoje trabalham de forma independente, com estúdios construídos ou adaptados em suas residências, os chamados home studios. Seja em um grande estúdio profissional de gravação, ou em um home studio, o estudo da acústica do local é imprescindível para se obter boa qualidade nas gravações. Uma das áreas aplicadas da acústica é a avaliação e desenvolvimento de ambientes utilizados para gravações de áudio. Essa área contempla diversas avaliações de grande valia, quando se trata da garantia da qualidade acústica das salas em um home studio. Reverberações, isolamento sonoro, entre outras variáveis de projeto definem parâmetros acústicos do ambiente. A obtenção destes parâmetros e adaptações do local para diferentes usos, entre outras características utilizadas para avaliação da qualidade sonora dos ambientes, podem ser dadas através do estudo e avaliação do modelo acústico do estúdio, visto que esses parâmetros estão diretamente relacionados com os materiais construtivos, dimensões e arquitetura do ambiente. Este trabalho teve como objetivo o estudo do efeito desses parâmetros na acústica dos ambientes e a criação de modelos numéricos representativos de predição acústica, a partir da análise e avaliação em dois estúdios diferentes. Assim, provendo embasamento teórico-... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The phonographic industry, with the advent of digital recording equipments, su ered great transformations in the last few years. The most remarcable change is the migration of musicians that used to work with great record labels before and nowadays work in an independent way, with studios constructed in their residences, the so called home studios. Whether in a large professional recording studio, or at an home studio, the study of local acoustics is imprescindible for obtaining good recording quality. One of the applied areas of acoustics is the valuation and development of enviroments used for audio recordings. This front of study includes many evaluations of great worth when it comes to guaranteeing the acoustic quality in a home studio. Reverberations, sound insulation, between other variables de ne the acoustic quality of the enviroment. The obtention of these parameters and adptations of the room for di erent kind of usage, along with other characteristics utilized for the valuation of acoustic quality of enviroments, may be given through study and valuation of an acoustic model of the studio, since these parameters are directly related to the building materials, dimensions and architecture of the environment. The objective of this work was to study the e ect of these parameters on the acoustics of the environments and the creation of representative numerical models of acoustic prediction, from the analysis and evaluation in two di erent studios, so that it is possible ... (Complete abstract click electronic access below) / Mestre

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Concave surfaces are often considered to be detrimental or precarious in room acoustics, especially because of the impact they have on the distribution of sound energy. However, it is often difficult to avoid such surfaces in buildings with specific architectural functions. A primary example of this involves mosques, which are sacred places of worship for Muslims. In keeping with the Islamic architectural style, most mosques incorporate a symbolic centralized domed ceiling as part of their room structures. These domes are open on the bottom and coupled to the acoustic spaces below. In many cases, the lower spaces may be idealized rectangular enclosures. Owing to the distinctness and ubiquity of this basic architectural form, a thorough, fundamental analysis of such environments would be useful to the architectural acoustics community. In this study, predictions from EASE (trademark) computer models were compared to the results derived from physical scale model measurements. The scale model measurement techniques involved evaluation of impulse responses in a 1:12 scale model of Darussholah mosque, in East Java, Indonesia. A miniature human voice source was created to carry out the impulse response measurements. It was carefully evaluated to ensure that it produced adequate frequency response and directivity comparable to an actual human voice. Acoustical parameters were derived from the impulse responses. Statistical analysis using ANOVA and t-tests were used to compare results from the measurements with variations of domed ceiling configurations and other aspects of the measurement setting. Conclusions were based on these comparisons and on auralization listening tests in order to ascertain the elements that produced the most significant impact on the mosque acoustics. The analysis helps establish criteria for good acoustics in mosques and other buildings with domed ceilings.

In order to facilitate the acquisition and accurate interpretation of intensity and energy density data in high-amplitude pressure fields, the expressions for intensity and energy density are examined to ascertain the impact of nonlinear processes on the standard expressions. Measurement techniques for estimating acoustic particle velocity are presented. The finite-difference method is developed in an alternate manner and presented along with bias and confidence estimates. Additionally, two new methods for estimating the local particle velocity are presented. These methods appears to eliminate the errors and bias associated with the finite-difference technique for certain cases.

The purpose of this study was to present a comprehensive analysis of the acoustical properties of the trumpet mouthpiece. The first section will be concerned with the individual parts of the mouthpiece and their interrelationship. The second portion of the study will be the physical analysis of three commonly used trumpet mouthpieces. For this study, five examples of each size have been selected. The third section will present a tonal analysis of the selected mouthpieces. These investigative procedures will attempt to recognize any relationships between the individual mouthpieces and the resulting tones.

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