Acoustical engineering: A complete academic undergraduate program in Brazil.

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.

An algorithmic approach to electroacoustical analogies.

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.

Impedance measurement of non-locally reactive samples and the influence of the assumption of local reaction.

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.