Students in introductory courses on speech science have considerable difficulty in understanding the articulatory and acoustic phonetics involved in the production of vowels. A computer-based course of instruction has been developed that is intended to increase students' understanding of the interrelationships of the important concepts in this difficult area [Jackson et al., J. Acoust. Soc. Am. 95, 3014(A) (1994)]. The present experiment evaluated the computer-based exercises along with the traditional lecture method. Students were assigned to two groups, and each group received both the lecture and computer instruction but in a different order. Cognitive structures tests using similarity ratings were administered to assess students' understanding of the material before and after each type of instruction. Twenty concepts from the disciplines of articulatory and acoustic phonetics of vowels were paired for similarity ratings. Students' mental models were compared to those of experts using ``Pathfinder'' network, multidimensional scaling, and profile correlations. The students' shift toward expert-like patterns was small after lecture-only or computer-only presentations. The shift was moderate when the computer was first and lecture was second. The shift was large when the lecture was followed by the computer.