Laminate flooring manufacturers have received negative feedback from customers on the sound quality of laminate flooring installations. Customers express a preference for the sound of traditional hardwood floors over that of laminate flooring composites. Consumers notice a difference between the sounds created by a footfall between laminate flooring and hardwood flooring. They perceive the laminate flooring sound of a footfall to be annoying and associate it to the flooring being of a lower quality. No objective test procedure exists to validate the marketing claims of the performance of these products. The objective of the work in this thesis is to develop a test method that evaluates the human perception of the sound quality of footfall noise on laminate flooring composites.

Orientador: Stelamaris Rolla Bertoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil / Made available in DSpace on 2018-08-01T21:56:33Z (GMT). No. of bitstreams: 1 Neto_MariadeFatimaFerreira_M.pdf: 3390488 bytes, checksum: 675867527ebf6bb839c6a6e6317a33a3 (MD5) Previous issue date: 2002 / Resumo: o estudo de barreiras acústicas ao ar livre é o objeto de estudo deste trabalho. Esse estudo abrange duas perspectivas:o desempenho acústico das barreiras e a qualidade sonora. Sobre as duas perspectivas,foram realizadas avaliações que compreendem aspectos objetivos e subjetivos. Entende-se como aspectos objetivosos resultadosdas medidasfisicas,como a perda por inserção das barreiras, para a avaliação do desempenho acústico e, os resultados dos parâmetros psicoacústicos definidos por Zwicker, para a avaliação da qualidade sonora. Em relação aos aspectos subjetivos, foi constituído um júri, que opinou sobre a sensação percebida de um estímulo sonoro,recebido através da barreira.Os resultadosdas avaliaçõesde ambos os aspectos, foram comparados a fim de se obter a avaliação final do desempenho das barreiras.A obstrução visual da fonte sonora, por uma barreira acústica, pode causar redução de ruído, nem sempre verdadeira.Os resultados mostram que o desempenho real das barreiras nem sempre corresponde ao desempenho subjetivo porém,reforçam a idéia de que as barreiras acústicas atuam como um auxiliar para a redução de ruído ao ar livre. Há fortes indícios de que os parâmetros psico acústicos poderão ser usados como método de desempenho de barreiras (qualidadesonora) / Abstract: The outdoor acoustic barriers study is the object of this work. This study includes two perspectives: the acoustic barrier performance and the sound quality. These two perspectives were evaluated considering objective and subjective aspects. The physical results, such as the barrier insertion loss, was used to evaluate the objective acoustic performance.The results from the psychoacoustic parameters defined by Zwickerwere used to objectively evaluate the sound quality. Regarding the subjective aspects, a jury was fonned to judge the perceived sensation ftom sonorous stimulus received through the barrier. The experimentalresults of both aspects were comparedto get the final evaluationof the acoustic barriers performance.The sound source visual obstruction caused by an acoustic barrier, ean cause noise reduction which is not always true. The results show that the barrier real performance does not always correspond to the subjective perfomacee,but also reinforce the idea that the acoustic barriersis an auxiliar element to reduce outdoor noise. There are strong evidencesthat the psychoacoustic parameters can be used as a means of barrier performace evaluation (soundquality) / Mestrado / Edificações / Mestre em Engenharia Civil

Characteristics of heating, ventilation, air conditioning and refrigeration (HVAC&R) equipment sounds and people's responses to them were studied in order to develop models to predict annoyance from recordings of the sound. These models are intended to address shortcomings of currently used methods for HVAC&R product sound assessment. Coupled with sound prediction models, the annoyance models will be used to monitor and guide improvements to HVAC&R equipment sound quality throughout the product design process: from virtual early design, through to the prototyping and product refinement stages. Responses to residential and refrigerated truck product noise was studied; both produce broadband random noise and families of harmonics related to rotating and reciprocating components within the system. Tests were conducted to determine how people describe HVAC&R equipment sounds; how their descriptions relate to sound characteristics and overall assessments; and to develop models that relate predicted strengths of sound characteristics to the overall assessment. Annoyance models were developed for each types of product. Loudness and spectral balance metrics are included in models for both types of product. Inclusion of a tonalness metric improved models for residential units, and roughness and impulsiveness metrics improved models for refrigerated truck units. The models developed were used to predict responses in the other tests and there was good agreement between predicted and measured responses. An illustration of the use of the annoyance models, in conjunction with sound visualization and signal modification techniques, to guide improvements to product sound quality is given.

Two separate methods are presented to aid in the creation and evaluation of acoustic simulations. The first is a hybrid method that allows separate low and high-frequency acoustic responses to be combined into a single broadband response suitable for auralization. The process consists of four steps: 1) creating separate low-frequency and high-frequency responses of the system of interest, 2) interpolating between the two responses to get a single broadband magnitude response, 3) adding amplitude modulation to the high-frequency portion of the response, and 4) calculating approximate phase information. An experimental setup is used to validate the hybrid method. Listening tests are conducted to assess the realism of simulated auralizations compared to measurements. The listening tests confirm that the method is able to produce realistic auralizations, subject to a few limitations. The second method presented is a machine learning approach for predicting human perceptions of audio fidelity and sound quality. Several algorithms are compared and various audio features considered in developing the machine learning models. The developed models accurately predict human perceptions of audio fidelity and sound quality in three distinct applications: assessing the fidelity of compressed audio, evaluating the fidelity of simulated audio, and comparing the sound quality of loudspeakers. The high accuracies achieved confirm that machine learning models could potentially supplant listening tests, significantly decreasing the time required to assess audio quality or fidelity.

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Sound quality is an important measure depicting the quality of a machine as well as the comfort in its usage. However, it being a subjective measure, not only is it difficult to capture it ahead of time but also necessitates time and cost expensive jury testing. Thus, it is worthwhile to be able to effectively predict the results of the jury study from metrics that can be objectively measured. The aim of the thesis is twofold: first, to establish neural network models to predict subjective sound quality metrics from objective metrics and second, to interpret the model to understand the relative importance of each objective metric towards a specific subjective rating. Ultimately the thesis aims to pave the way for inclusion of sound quality metrics in the early design stages. From the study, it was evident that neural networks’ performance was at least equal to or better than linear or quadratic models. The connection weights method, the profile method, the perturbation method, the improved stepwise selection method and linear regression method were the interpretation algorithms found to work well in all simulated data-sets. They also gave comparable results on the real data-sets. Neural networks were shown to have the potential for giving low prediction errors while maintaining interpretability in sound quality applications. The data scarcity study gave an idea of the scale of performance enhancement that can be achieved with more data and can act as a useful input for deciding the number data points. / Ljudkvalitet är ett viktigt mått som skildrar en maskins kvalitet såväl som bekvämlighet i dess användning. Det är emellertid ett subjektivt mått, inte bara är det svårt att fånga detta i förväg men också att det kräver både tid och dyra jurytestningar. Det är därför värdefullt att kunna effektivt förutsäga de resultaten av jurystudien från mätvärden som kan mätas objektivt. Syftet med arbetet är tvåfaldigt: det första är att etablera neuronnätsmodeller till att förutsäga subjektiva ljudkvalitetsmätvärden från objektiva mätvärden. Det andra är att tolka modellen till att kunna förstå den relativa betydelsen av varje objektivt mätvärde mot en specifik subjektiv bedömning. I sista hand syftar arbetet till att bana vägen för inkludering av mätvärden för ljudkvalitet i de tidiga designfaserna. Utifrån studien var det uppenbart att neuronnäts prestanda var åtminstone lika med eller bättre än de linjära eller kvadratiska modellerna. Anslutningsviktsmetoden, profilmetoden, störningsmetoden, den förbättrade stegvisa urvalsmetoden samt den linjära regressionsmetoden var tolkningsalgoritmerna som visade sig att fungera väl på alla simulerad datauppsättningar. De gav också jämförbara resultat på de verkliga datauppsättningarna. Neuronnät visade sig att ha potential att ge låga prediktionsfel samtidigt som de bibehåller tolkningsbarhet i applikationer för ljudkvalitet. Studien av dataknapphet gav det en uppfattning om storleken på prestandaförbättring som kan uppnås med mer data och kan fungera som en användbar input vid bestämning av antalet datapunkter.

The increasing number of electric and hybrid vehicles in urban areas has shown to be beneficial in reducing both air and noise pollution. However, the lack of sound when driving at low speed has negatively affected the pedestrian safety since many rely on the vehicle sound for orientation. Regulatory bodies have therefore introduced minimum sound requirements for all silent vehicles, which has resulted in a key challenge for car manufacturers to develop external warning signature sounds. The objective of this project has been to study how these signals should sound in order to fit the image of electric and hybrid vehicles and minimize noise and annoyance. To complete the study, five sound concepts with different characteristics and rhythms were developed using the concept generation process. In order to gain subjective impressions of the sounds, three measurement methods were utilized. The first listening test was performed to eliminate the possibility that the sound samples would be perceived variously loud in the upcoming tests. The second listening test was performed to gain information on how suitable the signals are for electric and hybrid vehicles, and the third listening test was conducted to obtain information on how much annoyance the signals contributed with. A reference signal representing an internal combustion engine was included in the tests as well. The results of the measurement methods showed that the sound samples with long tone sequences were more preferred than those with short tone sequences, and that the artificial approach was more popular than the sound of an internal combustion engine vehicle. It was also established that additional tests need to be performed in order to confirm that these results are valid. It was suggested that field tests should be conducted and that new sound concepts should be developed based on the results of these tests.

La problématique de la qualité sonore à l'intérieur de l'habitacle est importante dans le domaine de l'automobile, particulièrement dans le cas des véhicules haut de gamme. La réduction du bruit des motorisations thermiques et l'émergence de solutions hybrides ou électriques ont transformé la perception du bruit par l'utilisateur. La contribution acoustique des équipements tels que le module de ventilation est devenue prépondérante et doit donc être étudiée dès la phase de conception. Afin de traiter la problématique acoustique et de fournir un outil de prototypage virtuel, ce travail a été mené dans le cadre du projet Cevas (Conception d'Equipement de Ventilation à Air Silencieux). Une approche de synthèse acoustique permet d'identifier les composants responsables du bruit produit et transmis. Leurs caractéristiques actives, traduites par un terme de source, et passives, traduites par un terme de perte par transmission, sont étudiées et représentées par des spectres en bandes fines. Cette définition permet la synthèse sonore du bruit produit et l'étude de la qualité sonore à l'aide de lois d'acceptation. Le ventilateur est la source principale d'un module de ventilation. Son terme de source est prédit par une loi originale, basée sur des données expérimentales et inspirée de la loi ASHRAE. Le terme de source du volet est caractérisé à l'aide de la méthode empirique de Nelson et Morphey. Le terme de source de l'échangeur thermique est déterminé à partir de mesures. Les termes de perte par transmission du volet et de l'échangeur thermique sont obtenus à l'aide de la matrice de diffusion expérimentale. L'environnement du milieu de propagation acoustique a une influence sur le bruit produit. La transposition des termes de source d’un environnement d'essai normalisé à un environnement représentatif des modules de ventilation a donc été étudiée. La méthode développée repose sur la modélisation du terme de source par une force volumique dont l'amplitude et la localisation sont indépendantes du milieu. Le développement de cette méthode a nécessité des modèles analytiques et numériques. L'application de la méthode pour un ventilateur placé dans un module de ventilation simplifié est confrontée à des essais. Un outil de prototypage virtuel est présenté pour un module de ventilation simplifié. La prédiction du bruit produit est confrontée à des mesures de puissance acoustique. L'usage de l'outil de prototypage permet d'étudier la contribution de chaque composant en considérant différents cas de ventilation. / The sound quality problem inside the car cabin is important in the automotive field, especially in the case of upmarket vehicles. The reductions of the noise produced by internal combustion engines and the emergence of hybrid and electric solutions have transformed the perception of sound by the user. The acoustic contribution of equipment such as the HVAC has become paramount and must be studied from the design stage. In order to treat acoustic problems and provide virtual prototyping tools, t his thesis was conducted within the framework of the Cevas project (Conception d'Equipement de Ventilation à Air Silencieux) to study and characterize the components of an automotive HVAC. An acoustic synthesis approach is used to identify the components responsible for the noise generated and transmitted. Their active and passive properties, translated by a source term and a transmission loss, have been studied and represented by thin strips spectra. This definition allows sound synthesis of the noise produced and the study of sound quality using acceptance laws. The source term of the fan is predicted by an original law, based on experimental data and inspired by ASHRAE law. The source term of the flap is characterized by using the Nelson and Morphey empirical method. The source term of the heat exchanger is determined from measurements. The transmission losses of the flap and the heat exchanger are obtained using the scattering matrix. The transposition of the source terms from a standardized test environment to an acoustic medium representative of the HVAC has been studied. The developed method is based on modeling t he source term by acoustic excitation whose amplitude and location are independent of the environment. The application of this method has required analytical and numerical models to characterize the acoustic excitation. In the case of the fan, its propagation in a simplified HVAC is studied. A virtual prototyping tool has been implemented in the case of the simplified HVAC. The noise prediction is confronted with sound power measurements. The use of the prototyping tool allows studying the contribution of each component considering various cases of ventilation.

<p dir="ltr">As speeds and directions of the vehicle and wind change, the unsteady flow creates variations in wind noise, which can be referred to as non-stationary wind noise. To investigate people's perceptions of non-stationary wind noise, a method to simulate the non-stationary wind noise is needed. Previously, a method was developed that used stationary recordings taken at several wind speeds and directions to form functions that relate the 1/3 octave sound pressure level with wind speed and direction. These functions are used to create time-varying filters based on provided time histories of wind speed and direction. A reference wind noise measurement is then filtered to produce the sounds. To reduce the time cost of taking many stationary measurements, an improved method was investigated. At each yaw angle, one speed sweep wind tunnel measurement was used to estimate the relationship between sound pressure level and wind speed. Two partially correlated white noise signals were then filtered to simulate binaural sounds that had a similar coherence structure between the left and right ear sounds to that observed in binaural measurements in the vehicle. The accuracy of the simulations was validated by comparing wind noise simulations with wind tunnel and on-road vehicle interior noise measurements. For the on-road measurements, a noise decomposition method based on noise source measurements was used to estimate the road/tire noise, which was then added to the simulated wind noise to make it comparable with the measured on-road noise. The time-varying loudness, and power spectral densities of the simulated and measured sounds were found to be well consistent. Besides, a method to simulate the turbulent wind speed time histories, which can be used as inputs to the wind noise simulation method, was developed. The von Karman model predicts the spectra of wind turbulence by assuming it to be a stationary random process. White noise signals can then be filtered to simulate the stable variations of wind speeds. The discrete gusts, which are the transient events in wind speed time histories, were also simulated by using an 8-parameter piecewise function. Eventually, the non-stationary wind noise and the turbulent wind speed simulation method can be a powerful tool when investigating sound perceptions of vehicle interior wind noise.</p>

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