The purpose of this study is two-fold. The first is to investigate changes over a decade in native English listeners’ judgment of the comprehensibility of speech read aloud by Korean EFL university students. The second is to examine the relative effects of acoustically measured prosodic features on comprehensibility. Acoustic data from 19 students (10 male and 9 female) who entered university in 2000 and 19 more (10 male and 9 female) who entered in 2012 were employed for comprehensibility judgment by 10 native listeners. The findings showed that the degree of comprehensibility by native speakers rose significantly from 2000 to 2012. General comprehensibility more closely correlated with suprasegmental than with segmental comprehensibility. A stepwise multiple regression analysis revealed that among the suprasegmental features of pitch ratio, duration ratio, intensity ratio, pitch range, and speech rate, speech rate is associated with comprehensibility to the greatest degree, followed by duration ratio. As for specific problem areas, vowels tended to be the most problematic area without any improvement in the pronunciation of segmentals, while there was a gender effect for suprasegmentals; female speakers improved in all the areas of stress, pause, rhythm, and intonation, whereas male speakers’ intonation improved more than other areas. (Incheon National University).