This study investigated the effects of three kinds of gloss conditions that is traditional non-CALL marginal gloss, computer-based audio gloss, and computer-based extended audio gloss, on reading comprehension of Iranian EFL learners. To this end, three experimental and one control groups, each comprising 15 participants, took part in this study. In order to ensure that the participants were from the right proficiency level, KET (Key Language Test) was used to select upper-intermediate proficiency learners. Participants in each group read two passages under one of the three mentioned conditions, with no gloss offered for control group. They all completed one pretest, one reading session, and one post-test. The data were analyzed using t-tests and one-way ANOVA. Statistical analyses of the results revealed that extended audio gloss group, who were provided with the voice of a speaker to read the meaning of the target word, as well as one example sentence, significantly outperformed the other groups. The results of this study provide some insights for teachers and administrators to review their curricula, approaches, and educational tools, and to consider the possibility of incorporating CALL technology into their teaching.