Enhancing a real-time audio laboratory using the MATLAB audio system toolbox
Audio output as part of laboratory experiments provides students with tangible motivation and a way in which to experience the impacts of signal processing first-hand. This paper presents an upgrade in a sophomore-level signal processing laboratory course by implementing The Mathworks,® Inc. MATLAB® Audio System Toolbox™ for real-time audio applications. The course in which this upgrade was implemented is required of all engineering majors and provides a foundation in the mathematical modeling and analysis of signals and of linear time-invariant systems. The laboratory component of the course utilizes applications of signal processing to motivate the breadth of the field which includes filters, AM modulation, and Nyquist sampling theory. The MATLAB® Audio System Toolbox™ implemented in this study replaces both the TMS320C6713 DSK (225 MHz) development board and the more recently examined Beagleboard-xM (1 GHz) board. Comparisons are made between these three platforms. This study was carried out by assessing both student and instructor observations and laboratory completion time using the Audio System Toolbox versus the TI-DSK board over four key laboratory experiments: Digital Audio Effects, Touch-Tone Phone, Voice Scrambler-Descrambler, and Sampling and Aliasing. When comparing student satisfaction levels, we found a statistically significant improvement (p ≈ 0.10) when students used the Audio System Toolbox™ over the TI-DSK board and showed no negative effect on the logistics of integration or usage, as reported by the students and laboratory teaching assistants. The motivation for this work comes at a time when real-time hardware for signal processing is becoming integrated into more multi-versatile computing platforms not necessarily dedicated to the task. In addition, the speed and memory of on-board computer microprocessors with audio outputs provides the resources necessary to realize audio processing real-time in the teaching laboratory environment. While the on-board computer microprocessors are not as robust as specialized external counterparts, their use has great impacts on classroom and learning potentials.
