Virtual acoustic prototyping (auralization) is the rendering of a virtual sound field that is created from the calculated acoustic response of a modeled structure. Auralization is useful in the design and subjective evaluation of buildings, automobiles, and aircraft. The virtual acoustic prototyping method in this thesis uses finite element modeling (FEM), the equivalent source method (ESM), and head-related transfer functions (HRTFs). A tradeoff exists between the accuracy of the auralization process and the number of equivalent sources (and thus computational power) that are required. The goal of this research is to validate (numerically and subjectively) a virtual acoustic prototyping method for use in structural design; this thesis illustrates the first attempt to apply the aforementioned methods to a structure that represents a typical building or automobile. The structure's acoustics were modeled using FEM, ESM, and HRTFs. A prototype of the modeled structure was built. A 36% correlation was achieved between the model and prototype. Slight variations in boundary conditions caused significant FEM error, but the data represented a typical structure. Psychoacoustic comparison testing was performed to determine the number of equivalent sources that must be used in an auralization to accurately recreate the sound field. The number was found to be dependent on the type of noise that is played to the test subject. A clear relationship between the numerical correlation of two sounds and the percentage of subjects who could hear a difference between those two sounds was established for impulsive, broadband, and engine noises. / Master of Science

Orientador: Jose Roberto de França Arruda / Dissertação ( mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T03:02:12Z (GMT). No. of bitstreams: 1 Kawano_RafaelRogora_M.pdf: 8279591 bytes, checksum: cc9b56dd0845c482ecd99e0ccfde6bd2 (MD5) Previous issue date: 2009 / Resumo: Neste trabalho foi explorado o mecanismo de geração de ruído de pneumáticos automotivos conhecido como ruído de martelamento, segundo a abordagem da Prototipagem Virtual Sonora. Foi implementado um modelo teórico disponível na literatura que considera apenas a pluralidade de passos de blocos na banda de rodagem. A partir dele, dois outros modelos foram desenvolvidos e implementados considerando, além da pluralidade de passos de blocos, os efeitos do contato pneu/pavimento (distribuição da pressão de contato), da multiplicidade de carreiras de blocos, da defasagem helicoidal entre as carreiras e da deflexão sob carga e a definição de um perfil do sinal de excitação dos blocos. A sensibilidade da resposta temporal e espectral aos parâmetros dos modelos foi avaliada. Modelos de caminhos estruturais foram implementados e se basearam em dados experimentais. Por fim, o programa desenvolvido sintetiza o ruído virtual gerado pelo contato pneu/pavimento para diferentes configurações do pneu previstas pela modelagem, podendo ser ouvido através de fones de ouvido e permitindo a realização de uma análise subjetiva. / Abstract: This study explored the automotive tire noise generation mechanism known as hammer noise, according to the Virtual Acoustic Prototyping approach. A theoretical model available in the literature that considers only the plurality of block pitches in the tread band was implemented. Based on this model, two improved models were developed and implemented considering, besides the plurality of block pitches, the effects of the tire / pavement contact (contact pressure distribution), the number of block ribs, the helical gap of the careers, the deflection of the tire under load and the definition of a profile of the resulting excitation signal. The sensitivity of the response in the time and frequency domains to the tire parameters was evaluated. Models of structural borne paths based on experimental data were implemented. Finally, the program developed synthesizes the virtual noise generated by the tire / pavement contact for different configurations of the tire, which can be listened in headphones, thus enabling a subjective analysis of hammer noise. / Mestrado / Mecanica dos Solidos / Mestre em Engenharia Mecânica