Prosodic remedies of Korean talkers' English L2 speech: Optimal pitch and speech rate

The current study investigates native English listeners' perceived foreign accent for pitch- and duration-manipulated speech of Korean EFL talkers with high and low proficiency. This work contents that low proficiency talkers' L2 speech can be perceptually better accented when a single prosodic parameter such as pitch or speech rate is merely corrected. As nonnative talkers' proficiency was divided into three categories, high, intermediate and low in the Accentedless Rating task, low talkers were categorically promoted to the intermediate when H* and L* were remedied more native-like and their L2 speech was synthesized to be faster. The corrected prosodic features seemed to be readily detected by native listeners because such corrections might be comparatively salient over the segmental features seriously deviant from native norms in their interlanguage. The results of the current experiment suggested actual numeric values of optimal pitch and speech rate for upgrading low talkers' proficiency; H* should increase roughly by 30% to 45% higher than the ones that they usually produce in statements, and L* should deepen approximately by 20% to 40% lower than in their normal production of yes-no questions. Speech rate should be 1.2 to 2 times faster for low talkers to be judged as intermediate. On the other hand, Korean high proficiency talkers didn't show a categorical decline to intermediate when pitch or speech rate was synthetically deteriorated. Due to their little accented L2 speech, phonological/phonetic features, which are very similar to those of native speakers, seemed to firmly tolerate the degrading portion of prosody. In addition, the actual numeric values of pitch and speech rate obtained in the results should be applied to the pedagogical environment and used as references to facilitate improving low talkers' proficiency.