Pronunciation is an important part of language proficiency because of its immediate role in language judgments. Nevertheless, it has often been overlooked and sometimes neglected in favor of grammar and vocabulary in SLA research (Neri, Cucchiarini, Strik, & Boves, 2002). Taking into consideration the importance of pronunciation instruction and the central impact of suprasegmentals on comprehensibility (Celce-Murcia, Brinton, Goodwin, & Griner, 2010; Isaacs, 2008), a four-week fully online pronunciation tutor (the Supra Tutor) was developed as an attempt to address gaps in pronunciation instruction identified by previous research (e.g., marginalization of pronunciation instruction, lack of trained instructors, and lack of connection between theory and practice) (Derwing & Munro, 2005).

The primary purpose of this mixed methods study, an adapted version of the embedded experimental model, was to assess whether a fully online pronunciation course can help international teaching assistants (ITAs) improve their comprehensibility. The study also analyzed ITAs’ evaluation of the Supra Tutor in regards to usefulness, level of interest, and quality of the materials. Finally, the study examined the contributions of suprasegmentals (word stress, rhythm, and intonation) to comprehensibility ratings and the language features that trained raters attended to when judging the comprehensibility of L2 speakers.

Twelve ITAs from several L1 backgrounds delivered a 7-minute field-specific lecture, which was videotaped for later analysis. Then, the ITAs completed the four-week online training. After the training, the ITAs delivered another 7-minute lecture on a related topic and were once again videotaped. Finally, the ITAs were rated for comprehensibility by different groups of naïve and trained native listeners. The rating instruments were a holistic comprehensibility scale used by naïve native listeners and a language-specific scale used by trained raters. Verbal protocols were employed during trained rater sessions. Both scales were developed specifically for this study.

Findings indicated that the Supra Tutor was effective in providing pronunciation instruction as four out of the 12 ITAs showed significant comprehensibility improvement. The findings also indicated that the ITAs found the tutor to be useful, appealing, and of excellent quality. As for the contributions of suprasegmentals to comprehensibility, the analysis of trained rater data indicated that raters tended to place similar emphasis on rhythm and intonation. However, word stress was a suprasegmental that raters attended to when judging the comprehensibility of learners at all levels of proficiency. In addition, findings revealed that often there was not a clear connection between comprehensibility ratings and suprasegmental ratings. Also, individual trained raters focused on a variety of language features when judging L2 speech. Segmentals, especially vowels, however, were the most common source of disagreement among the raters.

The results of this study contribute to the area of technology applied to pronunciation instruction in that it is the first study to employ fully online pronunciation training through the use of a tutor designed to target specific suprasegmental features and specific learner needs. The findings in this study have several pedagogical implications. First, the tutor was perceived to keep learners engaged and motivated to complete the training, which is an indication that this kind of pronunciation instruction can be helpful to raise learners’ motivation to improve their pronunciation skills. Second, the Supra Tutor can be easily adapted for different audiences and contexts, which can help solve the lack of trained teacher conundrum. Third, in addition to learner training, an online approach such as the Supra Tutor has the potential to serve as a teacher-training tool. The Supra tutor can raise teachers’ awareness of the pronunciation features of English, help them understand how to structure their own classes, and give them the confidence to embrace the teaching of pronunciation.