The present study is focused on product development and aims to verify the benefits of the use of computer simulation as a design tool in the industry speakers. For this reason every stage of a product development company in the speakers will be analyzed comparing the traditional method, which uses interactions between prototypes and experiments with the organization based on computational modeling philosophy. Computer modeling will be performed using the finite element method. It is known that with the fierce market competition, organizations are seeking alternatives in tools, processes and technologies that will bring some difference and add value to the final product, and thus differentiate itself from competitors. As a premise for the use of computer simulations, the characterization of the mechanical properties of the materials used in making the speaker is required. Therefore, the paper also proposes to implement a method capable of accurately obtaining the necessary mechanical properties such as Young s modulus, damping, density, etc. Although the study is focused on an industry speakers, this research also applies to organizations that have the stage of product development in their deal flow. Through this comparison methods, the research aims to enable managers responsible for product development, the pursuit of sustainable growth by enhancing the competitive position and reducing the vulnerability of their stay in the market. In this sense we propose a case study, evaluating methods, the feasibility and benefits generated through computational modeling, always seeking opportunities that aim to ensure the creation of value for the product and hence to the end customer. / O presente estudo esteve focado no desenvolvimento de produto e teve por objetivo verificar os benefícios da utilização da simulação computacional como ferramenta de projeto na indústria de alto-falantes. Para isso, toda a etapa de desenvolvimento de produto de uma empresa do ramo de alto-falantes foi analisada comparando o método tradicional, que utiliza interações entre protótipos e experimentos, com a filosofia embasada no uso da modelagem computacional. A modelagem computacional foi realizada através do método dos elementos finitos. Sabe-se que, com a competição acirrada do mercado, as organizações buscam alternativas em ferramentas, processos e tecnologias que as tragam algum diferencial e acrescentem valor ao produto final, e assim as diferencie das empresas concorrentes. Como premissa para o uso de simulações computacionais, se faz necessário a caracterização das propriedades mecânicas dos materiais utilizados na confecção do alto-falante. Portanto, o estudo também apresentou e implementou um método capaz de obter com precisão as propriedades mecânicas necessárias, tais como: Módulo de Young, amortecimento, densidade, etc. Embora o estudo esteja focado em uma indústria de alto-falantes, esta pesquisa também se aplica às organizações que possuem a etapa de desenvolvimento de produto em seu fluxo de operações. Através desta comparação de métodos, a pesquisa possibilita aos gestores responsáveis pelo desenvolvimento do produto, a busca por crescimento sustentável melhorando a posição competitiva e reduzindo a vulnerabilidade de sua permanência no mercado. Nesse sentido é proposto um estudo de caso, avaliando os métodos, a viabilidade e os benefícios gerados através do modelamento computacional, sempre buscando oportunidades que visem assegurar a geração de valor para o produto e consequentemente para o cliente final.

El objeto de esta tesis se centra el estudio del comportamiento acústico de estructuras multicapa, utilizando como herramienta, entre otras, la denominada "Holografía acústica de campo cercano" (NAH, Nearfield Acoustical Holography). Las conclusiones obtenidas y las herramientas desarrolladas en este estudio tienen implicaciones en dos ámbitos, el aislamiento acústico con particiones ligeras multicapa, y la optimización de la radiación de sistemas electroacústicos basados en la vibración de un panel provocada por un elemento excitador de tipo dinámico (caso de los altavoces planos). El proceso para conseguir predicciones acertadas del comportamiento de estructuras multicapa, tanto desde el punto de vista de la aplicación acústica de la edificación, como el electroacústico (mejora de prestaciones de altavoces), debe partir, necesariamente de un conocimiento preciso de las características acústicas de los componentes, es decir, cada una de las capas. Este estudio constituye la primera fase de la investigación y del trabajo. La validación de las teorías sobre el aislamiento acústico lleva contigo el ensayo de diferentes materiales y configuraciones. El objeto es aumentar al máximo el índice de aislamiento de una cierta configuración, intentado disminuir en lo posible los costes. El estudio del comportamiento acústico de distintas configuraciones suele realizarse en cámara de transmisión. Los resultados de las medidas en estas condiciones no tienen por qué coincidir con los obtenidos con medidas "in situ", ya que las condiciones de montaje son hasta cierto punto incontrolables. Existen diversos trabajos donde se desarrollan los diferentes modelos, teorías y técnicas de medición con este fin, desde modelos y teorías para caracterizar materiales absorbentes hasta métodos de caracterización de materiales absorbentes medidos en el tubo de Kundt. También existen medidas de una determinado variable acústica, permiten obtener los parámetros de entrada necesarios para los progr / Escuder Silla, EM. (2005). Estudio del comportamiento acústico de estructuras multicapa mediante nah [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1860 / Palancia

This thesis deals with calculation of THD dependency on signal frequency and calculation of Rub & buzz distortion using MATLAB software. Thesis includes generation of signals suited for THD measurement, playback and recording using sound card and APx series 500 device. The APx device controlling and data acquisition by MATLAB is also addressed. Loudspeaker electric model is discussed for the use of Rub & buzz measurement.

Parametric acoustic arrays are ultrasonic-based loudspeakers that produce highly directive audio. The audio must first be preprocessed and modulated into an ultrasonic carrier before being emitted into the air, where it will self-demodulate in the far field. The resulting audio wave is proportional to the double time-derivative of the square of the modulation envelope. This thesis presents a fully analog processor which encodes the audio into two Pulse Width Modulated (PWM) signals in quadrature phase and sums them together to produce a Single Sideband (SSB) spectrum around the fundamental frequency of the PWM signals. The two signals are modulated between 8% and 24% duty cycle to maintain a quasi-linear relationship between the duty cycle and the output signal level. This also allows the signals to sum without overlapping each other, maintaining a two-level output. The system drives a network of narrowband transducers with a center frequency equal to the PWM fundamental. Because the transducers are voltage driven, they have a bandpass frequency response which behaves as a first-order integrator on the SSB signal, eliminating the need for two integrators in the processor. Results show that the “SSB-PWM” output wave has a consistent 20-30dB difference in magnitude between the upper sideband and lower sideband. In simulation, a single tone test shows higher total harmonic distortion for lower frequencies and higher modulation depth. A two-tone test creates a 2nd order intermodulation term that increases with the frequencies of the input signals.

The work is focused on a design of an active loudspeaker system with a bi-amp amplifier and a digital input. There is described the theory of a loudspeaker enclosure design and its practical implementation. Furthermore the work deals with a design and construction of input circuits such as a preamplifier, Baxandall tone control, active crossover, all-pass filter and S/PDIF. On the basis of the amplifier´s theory the optimal construction of amplifiers and their design are selected. The complex design of the loudspeaker box is devised so that it would reach a maximum acoustic power during the preservation of a low distortion.

Die Diplomarbeit mit dem Thema: 'Konzeption und Herstellung von Systemdemonstratoren für miniaturisierte Im-Ohr-Lautsprecher mit drahtlosen Kommunikationsschnittstellen' konzentriert sich auf die Auslegung einer Schaltung eines neuartigen Lautsprechers, welche auf dem Prinzip der NED-Aktoren ('Nanoskaliger elektrostatischer Antrieb') arbeiten. Des Weiteren werden Gehäuse für die Im-Ohr-Anwendung als auch die Freifeldanwendung entwickelt.:Symbolverzeichnis Abkürzungsverzeichnis 1 Einleitung 2 Stand der Technik 2.1 Im-Ohr-Lautsprecher 2.2 Drahtlose Kommunikation 2.3 Kommerzielle Piezotreiber 3 Anforderungen an den Systemdemonstrator 4 Chipaufnahme 4.1 Anforderung 4.2 Konzeption und Umsetzung 5 Drahtlose Kommunikation 5.1 Anforderung 5.2 Konzept 5.3 Umsetzung 6 Verstärker 6.1 Anforderung 6.2 Konzeption und Umsetzung 6.2.1 Validierung des DRV2700 6.2.2 Thermisches Management der Verstärkerschaltung 6.3 Modellierung des Gehäuses für die Elektronik 7 Im-Ohr-Demonstrator 7.1 Anforderung 7.2 Konzeption und Umsetzung 8 Horn-Demonstrator 8.1 Anforderung 8.2 Konzeption und Umsetzung 9 Ergebnisse 9.1 Chipaufnahme 9.2 Verstärker 9.3 Gehäuse für Elektronik 9.4 Im-Ohr-Lautsprecher 9.5 Akustisches Horn 10 Realisierung mittels Entwicklungsplatine 11 Diskussion und Ausblick 12 Zusammenfassung Literatur Selbstständigkeitserklärung Anhang

Cette thèse porte sur l’identification de systèmes non linéaires représentables en séries de Volterra, et son application à des systèmes sonores. Les séries de Volterra, qui permettent de représenter une large classe de systèmes non linéaires, correspondent à un développement en série organisé par ordre d'homogénéité par rapport à l’entrée: chaque terme homogène est caractérisé par un noyau convolutif dont l’ensemble fournit une "signature complète" du système représenté. Les travaux présentés reposent sur le développement d’une étape préalable de séparation des termes de la série pour améliorer l’identification des noyaux de Volterra. Par rapport aux méthodes déjà existantes de séparation en ordres homogènes, basées sur des relations d’amplitudes entre signaux tests, l'approche adoptée dans cette thèse consiste à exploiter les relations de phase entre signaux afin d'obtenir une méthode robuste. Cela est tout d’abord obtenu de manière abstraite pour le cas de signaux d’excitations complexes. De cette idée, plusieurs méthodes adaptées au cas des signaux réels sont développées. Ceci amène à définir de nouvelles catégories de signaux pour décrire la sortie d’une série de Volterra, regroupant les contributions selon leurs propriétés de phase. Les méthodes de séparation proposées sont testées et appliquées à une pédale d’effet de guitare. Ensuite, des méthodes d’identification spécifiques aux nouveaux types de signaux sont présentées. Enfin, une méthode d’estimation des paramètres d’une représentation d’état à non-linéarités polynomiales est développée. Celle-ci est appliquée à un haut-parleur électrodynamique, dont les caractéristiques non linéaires sont étudiées. / This thesis addresses the identification of nonlinear systems that can be represented with Volterra series, and its application to audio systems. Volterra series give an input-output representation, approximated to within a given error, of any time-invariant continuous nonlinear system with fading memory. Technically, they correspond to a series expansion sorted by homogeneity order with respect to the input: each homogeneous term is characterized by a convolutive kernel whose set provides a "complete signature" of the modelled system. The works presented are based on the development of a preliminary step that consists in separating the series' terms to improve Volterra kernels' identification. Compared to existing homogeneous order separation methods, which are based on amplitude relationships between test signals, the approach chosen in this thesis is to exploit phase relationships between signals to obtain a robust method. This is first obtained in the theoretical case of complex excitation signals. From this idea, several methods suited to the use of real signals are developed. This leads to define new signals categories that describes the output of a Volterra series, sorting nonlinear contributions according to their phase properties. The proposed separation methods are applied and tested on a guitar pedal effect. Then, specific identification methods for the new types of signals are presented Finally, a method for estimating the parameters of a polynomial nonlinear state-space representation is developed. This is applied to an electrodynamic loudspeaker whose nonlinear characteristics are studied.

Loud stage sound is a known challenge for live sound engineers, and the goal of this study was to investigate stage sound's role in live rock music performed in small venues. Stage sound is known to be prominent in small rooms as the total sound energy produced tends to contain a large proportion of stage sound. It commonly addressed that if the PA is overpowered by direct sound from instruments on stage, the mixing engineer may lose control over musical balance and overall sound level. To understand how engineers handle this, 6 professional engineers were interviewed by using semi-structured interviews. Additionally, 14 shorter interviews were conducted with musicians to gain further insight in what attributes of stage sound are desirable for performers and how they are affected by engineers' decisions. Results were interpreted through thematic analysis. 8 main themes were identified, some of which contained several subthemes. These themes were 1) Managing instruments' stage sound, 2) Monitor systems, 3) PA systems - what sources need reinforcement?, 4) Strategies for even coverage, 5) Sound level management, 6) Limitations of small venues 7) What is "good sound"? and 8) Communication regarding stage sound levels.

Ces travaux concernent l'évaluation perceptive de la reproduction sonore. Le but de notre étude est de proposer un protocole permettant la caractérisation perceptive des non-linéarités et des phénomènes de distorsion modifiant le signal reproduit par un système tel qu'une enceinte acoustique. L'élaboration d'un tel protocole nécessite de rassembler de nombreuses enceintes et d'utiliser une méthode d'évaluation adaptée. Nous ne cherchons pas à évaluer la distorsion en terme de qualité globale mais plutôt à estimer les dissemblances perçues entre différentes enceintes distordues afin de révéler, grâce à une analyse multidimensionnelle MDS, les critères sur lesquelles les auditeurs se basent pour les différencier. Dans un premier temps, nous avons utilisé des signaux de synthèse afin de générer des échantillons dont la distorsion est contrôlable. Nous avons ainsi créé un corpus composé de nombreux échantillons distordus simulant ou se rapprochant du fonctionnement d'une enceinte acoustique avec différents types de non-linéarités. Ensuite nous proposons une méthode adaptée à l'évaluation de la dissemblance sur des corpus étendus que nous avons validée à partir de simulations et de tests d'écoute. Enfin, nous avons appliqué cette méthode d'évaluation sur le corpus d'enceintes que nous avons élaboré afin de tester l'utilisation du protocole proposé et de donner quelques résultats préliminaires concernant les dimensions perceptives liées à la distorsion non linéaire. / This work deals with the perceptual evaluation of the sound reproduction. Our aim is to elaborate a protocol allowing to assess the influence of nonlinearities and distortions of a loudspeaker. Such a protocol requires gathering a large set of loudspeakers together with an appropriate method for its evaluation. This study deals with the perceptual evaluation of dissimilarities between different loudspeakers rather than their absolute quality judgements. Thanks to a multidimensional scaling technique, this approach allows to uncover the criteria used by the listeners to differentiate various distorting loudspeakers. First, we used synthesized signals to generate samples of sounds resulting from controlled distortion. Numerous distorded stimuli have been generated that simulate sounds radiated by a loudspeaker. Then, we propose a method suitable for the evaluation of a large set of stimuli. In order to verify its application to the estimation of dissimilarity, simulations and listening tests have been conducted. Finally, this listening test method has been applied to the created set of distorting loudspeakers in order to verify the use of our protocol and provide some preliminaries results concerning the perception of nonlinear distortion.

Le Haut-Parleur Digital Matriciel (HPDM) est un moyen de transduction électroacoustique qui reçoit comme entrée un signal numérique et qui effectue la conversion vers l'analogique directement dans l'air. Il est constitué de plusieurs éléments rayonnants disposés au sein d'une matrice. Ces éléments seront désignés par le terme «speaklet» lorsqu'ils sont de tailles réduites. Le rayonnement acoustique du HPDM est en effet très sensible à la taille de la matrice, ce qui le rend tout particulièrement adapté à la technologie MEMS. Cette thèse porte sur l'étude de HPDM MEMS piézoélectriques. Après une introduction qui débute par certaines généralités jusqu'à se focaliser sur le sujet, la thèse aborde les modélisations multiphysiques des HPDM étudiés, le dimensionnement des speaklets puis les tests expérimentaux. Des modèles analytiques ainsi que des simulations numériques et par éléments finis sont mis en place et permettent de prédire le comportement mécanique des speaklets présentés, les pressions rayonnées par les HPDM et les puissances électriques consommées. Les speaklets sont ensuite dimensionnés à partir de l'empilement technologique afin de maximiser le niveau de pression qu'ils génèrent. Des tests expérimentaux permettent alors de valider la majorité des modèles ou au contraire de revenir sur certains d'entre eux pour les optimiser ou montrer leurs limitations. Les résultats ont en effet montré l'importance de la prise en compte des contraintes résiduelles, qui provoquent une déformée initiale des speaklets et modifient leurs fréquences propres, rendant alors l'utilisation de grands rayons inefficaces. En accord avec les modèles, les speaklets possèdent un comportement dynamique linéaire, ce qui permet de les caractériser à l'aide de fonctions de transfert. La théorie et les enregistrements sonores montrent alors qu'un HPDM composé de tels speaklets permet dans le meilleur des cas de produire une pression identique à celle générée par la même matrice pilotée en analogique. Dans notre cas, des taux de distorsions supérieurs ont été obtenus lors des reconstructions digitales, à cause des réponses non uniformes des speaklets, dues à des résistances d'accès différentes. Le HPDM présenté possède cependant d'autres avantages, le plus important étant la très faible consommation électrique qu'il est théoriquement possible d'atteindre en utilisant les méthodes de charges et de décharges adiabatiques. Le HPDM piézoélectrique MEMS apparait donc comme étant une technologie prometteuse. L'optimisation de notre premier prototype à l'aide des outils développés doit en effet conduire à un HPDM capable de générer une pression équivalente à celle obtenue en mode analogique, mais avec un rendement électroacoustique beaucoup plus important. Les futurs travaux devront ensuite se concentrer sur la conception de speaklets non-linéaires et sur la forme du pulse de pression qu'ils génèrent, afin de gagner en niveau sonore. / The Digital Loudspeaker Array (DLA) is an electroacoustic transducer which receives as input a digital signal and performs the analog conversion directly into the air. It consists of a plurality of radiating elements arranged in a matrix. These elements will be designated by the term “speaklet” when they are reduced in size. The acoustic radiation of a DLA is indeed very sensitive to the size of the matrix due to differences in path length, which makes it especially suitable for MEMS technology. This thesis is on the study of a piezoelectric MEMS DLA. After an introduction that is increasingly focused on the subject, the thesis addresses the multiphysics modeling of the DLA, dimensioning of the speaklets and experimental tests. Analytical formulas, numerical simulations and finite element models are developed and used to predict the mechanical behavior of the presented speaklets, the pressure radiated by the DLA and the electrical power consumption. The speaklet are then dimensioned from the technological stack (set in advance) in order to maximize the pressure level. Experimental tests involving the use of an anechoic chamber, an optical interferometer, a vibrometer and an impedancemeter validate most of the models. Otherwise, these tests are usefull for improving some of them or for showing their limitations. The results have shown the importance of the residual stresses, which cause an initial deformation of the speaklets and modify their resonance frequencies, thus rendering ineffective the use of large radii. In accordance with the models, the static deflection of the speaklets is nonlinear but their dynamic behavior is linear. This enables characterizations using transfer functions. Theory and sound recordings show that a DLA made of such speaklets can produce in the best case the same pressure to that generated by the same matrix driven in an analog way. In our case, more distortions were obtained in digital reconstructions because of non-uniform responses of the speaklets, due to different access resistances. However, the presented DLA has other advantages, the most important being the very low power consumption it is theoretically possible to achieve using the adiabatic charge principle. The piezoelectric MEMS DLA thus appears as a promising technology. The optimization of our first prototype using the developed tools should indeed lead to a DLA able to generate an equivalent presure to that obtained with analog control, but with a far greater electroacoustic efficiency. Future work should then focus on the design of nonlinear speaklets and on the shaping of the pulse of pressure they generate, in order to increase the total pressure level.