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Acoustics is a broad field of knowledge that extends branches all over the physics of wave phenomena, psychology, natural sciences, and engineering. It is taught, in general, as part of engineering, physics, or architecture programs, or even in graduate programs specialized in the theme. In Brazil, acoustics was taught in graduate programs, until the creation of Acoustical Engineering in 2009, at the Federal University of Santa Maria, an integral undergraduate program dedicated to acoustics, audio, and vibration (lasting ten semesters). This article presents its complete academic program, its creation process, and the professional establishment of the acoustical engineer. In the following, the program of study and subjects are elucidated and detailed, and the teaching methodologies used are also discussed. The program employs several active learning strategies, like project-based learning, aiming to transform abstract into concrete knowledge. The interaction of the university, the acoustical engineer, and society is also presented and clarified. The placement of graduates in fields and their workplaces are presented as outcomes. As a fundamental part of the engineer's formation, the infrastructure used, whether state-of-the-art or cost-effective equipment, is detailed in the context of teaching and research. Finally, some of the ongoing research projects of the students are described.

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The low-frequency behavior of acoustical transducers can be simulated with the so-called electroacoustical analogies (or lumped parameters). The main idea is that visual inspection of the transducer allows the derivation of an electroacoustic circuit that can be analyzed. The technique is computationally efficient and provides significant physical insight into the transducer. Electroacoustical analogies are taught today in many courses around the world. However, it is difficult to find reading material with an algorithmic approach to derive the electroacoustic circuit from the visual inspection of the transducer. This paper presents algorithms to derive the mechanical and acoustical circuits of transducer systems and how to couple the electrical, mechanical, and acoustical circuits for electrodynamic and capacitive transducers. A number of examples of the derivation are presented in detail. These techniques were conceived from an extensive search of the classical literature in acoustics and adapted to the teaching needs of undergraduate and graduate students of the Acoustical Engineering at the Federal University of Santa Maria in Brazil.

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This study examines the edge diffraction effect when a sound wave impinges and reflects off finite porous absorbers, flush-mounted in an infinite hard baffle. A theoretical analysis of the diffraction is given by taking a two-dimensional spatial Fourier transform of a plane wave impinging on a finite absorber. Numerical experiments are also presented to simulate the sound field above infinite and finite locally reactive absorbers and the measurement with an array of pressure sensors. In such cases, a regularized solution is used to separate the incident and reflected plane wave components, in the wave-number domain, including both propagating and evanescent waves. The properties of the wave-number spectrum are associated either with the specular reflection or with the diffracted components, caused by the interaction of the sound wave with the finite absorber. From the regularized solution, it is possible to reconstruct the surface impedance and the absorption coefficient of the sample. The influence of Gaussian noise on such measurements is also investigated. The use of propagating and evanescent waves on the sound field model led to an estimation of the absorption coefficient that depends just slightly on the size of the sample, which is a desired feature for in situ measurement methods.

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Resumo No início do ano de 2020, a Covid-19 - doença causada por um novo tipo de coronavírus - foi classificada como pandemia pela Organização Mundial de Saúde e acometeu países de todos os continentes, levando a morte de centenas de milhares de pessoas. No Brasil, a doença também se espalhou rapidamente, exigindo medidas de isolamento social. Marcadas pela superlotação e infraestrutura precária, as prisões brasileiras tornaram-se alvo de preocupação de órgãos nacionais e internacionais que demandaram medidas de desencarceramento. Nesse contexto, o presente artigo analisa a proposição do Departamento Penitenciário Nacional de utilização de contêineres para abrigamento de pessoas presas, na contramão da resolução 62/2020 do Conselho Nacional de Justiça, que pautou pela necessidade de redução da população privada de liberdade. Discute-se como a desconsideração por medidas de desencarceramento e a demanda por proposições ainda mais violadoras de direitos apontam para a ratificação de uma política de morte para as pessoas presas.

Resumen A principios de 2020, la Organización Mundial de la Salud y los países afectados de todos los continentes clasificaron la Covid-19 - una enfermedad causada por un nuevo tipo de Coronavirus - como una pandemia, lo que provocó la muerte de cientos de miles de personas. En Brasil, la enfermedad también se ha propagado rápidamente, lo que requiere medidas de aislamiento social. Marcadas por el hacinamiento y la precariedad de la infraestructura, las cárceles brasileñas se han convertido en un objetivo de preocupación para los organismos nacionales e internacionales que han exigido medidas de liberación. En este contexto, este artículo analiza la propuesta del Departamento Nacional Penitenciario de utilizar contenedores para albergar a los presos, en contra de la resolución 62/2020 del Consejo Nacional de Justicia de Brasil, que se guió por la necesidad de reducir la población privada de libertad. Se discute cómo el desprecio por las medidas de liberación y la demanda de propuestas aún más violadoras de derechos apuntan a la ratificación de una política de muerte para los presos.

Abstract At the beginning of 2020 Covid-19 - a disease caused by a new type of coronavirus - was classified as a pandemic by the World Health Organization and affected countries on all continents, leading to the death of hundreds of thousands of people. In Brazil, the disease has also spread quickly, requiring measures of social isolation. Marked by overcrowding and precarious infrastructure, brazilian prisons have become an issue of concern for national and international organizations that have demanded releasing measures. In this context, this article analyzes the National Penitentiary Department's proposal to use containers to shelter prisoners, which is against Resolution 62/2020 of the National Council of Justice, that pointed to the reduction of the population deprived of liberty. It is discussed how the disregard for releasing measures and the demand for even more rights-violating propositions lead to the ratification of a death policy for prisoners.

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In this paper, the measurement of the absorption coefficient of non-locally reactive sample layers of thickness d1 backed by a rigid wall is investigated. The investigation is carried out with the aid of real and theoretical experiments, which assume a monopole sound source radiating sound above an infinite non-locally reactive layer. A literature search revealed that the number of papers devoted to this matter is rather limited in comparison to those which address the measurement of locally reactive samples. Furthermore, the majority of papers published describe the use of two or more microphones whereas this paper focuses on the measurement with the pressure-particle velocity sensor (PU technique). For these reasons, the assumption that the sample is locally reactive is initially explored, so that the associated measurement errors can be quantified. Measurements in the impedance tube and in a semi-anechoic room are presented to validate the theoretical experiment. For samples with a high non-local reaction behavior, for which the measurement errors tend to be high, two different algorithms are proposed in order to minimize the associated errors.

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The pressure-particle velocity (PU) impedance measurement technique is an experimental method used to measure the surface impedance and the absorption coefficient of acoustic samples in situ or under free-field conditions. In this paper, the measurement uncertainty of the the absorption coefficient determined using the PU technique is explored applying the Monte Carlo method. It is shown that because of the uncertainty, it is particularly difficult to measure samples with low absorption and that difficulties associated with the localization of the acoustic centers of the sound source and the PU sensor affect the quality of the measurement roughly to the same extent as the errors in the transfer function between pressure and particle velocity do.

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