People listen to get information in oral communication, and may consciously or unconsciously draw inferences on speakers based on their voices. A variety of phonetic cues have been found relevant in perceiving personalities from speech. This correlation has been documented in research involving native speech perception, though perceptual judgements on personality parameters were reported varying across cases. The tendency and sensitivity in voice perception has also attracted attention on non-native communication, where both language proficiency and language-specific features are considered influential as well. It is thus interesting to examine if similar or different sets of phonetic cues may affect non-native listeners' assessment of voices and personality. This study examined English-as-a-second-language (ESL) speakers' listening comprehension and perception of personality when listening to speech samples in American English. Speech extracts were modified to include variations in temporal and spectral dimensions. Results show that modification to pitch seemed beneficial to improve ESL listeners' comprehension accuracy. The modification also resulted in more favorable judgement of personality traits. Changes to the speaking rate yielded similar positive correlation with comprehension and personality judgement.