Black box measurements – Using a family of electrical circuits as a tool for self-guided learning in acoustical engineering

Abstract

A partnership between Brazil’s first undergraduate program in Acoustical Engineering and the Institute of Technical Acoustics of RWTH Aachen University yielded in a didactic project that uses the engineering software MATLAB with the ITA-Toolbox to teach acoustic measurements. Simple electrical circuits are used to mimic typical behavior of acoustical systems. This low-cost solution has proven to be didactically very effective since it helps students to identify themselves with the measurement tasks. Two hardware solutions were developed-a simple oscillator circuit integrated into connectors of audio cables and a desktop box containing seven different transfer characteristics ranging from ideal linear and time-invariant to nonlinear and time-varying behavior. Undergraduate students of Acoustical Engineering used both devices in classroom experiments for self-guided learning by comparing their results to published results. Students were able to learn the fundamental concepts of acoustical measurements and to handle measurement tasks. Besides the practical experiences and the learning effect, the students were also encouraged to step into the open source routines of the software, understand the signal processing steps, adapt routines, and even write their own ones, e.g., a GUI that provides effective control of the measurement via touch-screens.