The influence of various general and stimulus-specific factors on the contribution of vision to heard roundedness was investigated by means of web experiments conducted in Swedish. The original utterances consisted of the syllables /ɡyːɡ/ and /ɡeːɡ/ of a male and a female speaker. They were synchronized with each other in all combinations, resulting in four stimuli that were incongruent in vowel quality, two of them additionally in speaker sex. One of the experiments was also conducted in Turkish, using the same stimuli. The results showed that visible presence of lip rounding has a weaker effect on audition than its absence, except for conditions that evoke increased attention, such as when a foreign language is involved. The results suggest that female listeners are more susceptible to vision under such conditions. There was no significant effect of age and of discomfort felt by being exposed to dubbed speech. A discrepancy in speaker sex did not lead to reduced influence of vision. The results also showed that habituation to dubbed speech has no deteriorating effect on normal auditory-visual integration in the case of roundedness.