No abstract

Freshman engineering courses are being widely implemented so that students can make an informed decision about their major. Module-based approaches that trade depth for the sake of breadth are often used to present each of the varied disciplines separately. Electrical engineering, an abstract and mathematically intense discipline, is particularly challenging to distill into a few hours. This paper describes a four-hour electrical engineering module that examines the role of electrical engineering in the manipulation of audio signals, developed for a new introductory engineering course at the United States Naval Academy. In the first hour, students were given a short presentation on biometrics (signals that can be used to identify a person) and participated in demonstrations of iris, face, and fingerprint recognition systems. They then completed a laboratory experiment in which they analyzed plots of speech (audio) signals, measured pitch frequencies, and identified male and female voices using that information. During the following hour, after a brief overview of A/D and D/A conversion, the students captured their own voices and viewed the quantized voice signals as oscilloscope images. They used a Matlab script to manipulate the sampling rate and quantization and to play back the modified signals, illustrating aurally the effects of changing these parameters. The last two hours of the module were spent on a small electronics project involving a "light organ." This discrete circuit consists of a microphone, an amplifier, and a series of band pass filters tuned to different frequency ranges. The filters drive LEDs that flash with an audio signal. Circuit boards were prefabricated with all components except for the band pass filter resistors in place. The students engaged in the design process by first identifying the desired frequency ranges for their filters using function generators and speakers, and then choosing resistor values using an Excel spreadsheet programmed with the filter's design equations. Finally, the students soldered their resistors into place and tested their circuits. Thus, within four hours, the students were exposed to digital systems, digital signal processing, electronics, frequency response and communications-all tied around the central and concrete theme of audio signals.