A study on intelligibility, comprehensibility and accentedness based on the application pattern of lateralization and nasalization rules in foreign-accented speech of Korean

This study aims to investigate the impact of application patterns of Korean phonological rules in foreign-accented speech on native speakers' comprehension. The phonological rules investigated here are lateralization and nasalization, which are considered the most difficult for foreign learners. Lateralization and nasalization are obligatory assimilation rules that frequently occur in spoken Korean. They involve the phoneme at the syllable boundary turning into a lateral or nasal sound during the assimilation process. For example, the words/j(sic)n + lak/'call' are pronounced as j(sic)l.lak, and 'front door'/ap + mun/as am.mun. A total of 2,340 foreign-accented utterances (39 learners *60 sentences) have been collected and sorted into three categories based on the application pattern of the phonological rule: 'applied', 'misapplied', and 'not applied'. Thirteen Korean native speakers have been exposed to thirty utterances, including all application patterns for each phonological rule. Listeners' comprehension has been measured by intelligibility, comprehensibility and accentedness. The primary argument of this paper is whether we should view the non-application of lateralization and nasalization rules as a pronunciation error that hinders the learner's communication abilities or simply as an unnatural pronunciation that results in foreign-accented speech. The results showed that the non-application of nasalization rules, especially liquid nasalization and obstruent + liquid nasalization, had a direct impact on listeners' comprehension. This suggests that learners of Korean need to be aware of these phonological rules and apply them correctly in communicative situations. This study also determined which pronunciation elements need to be taught during a Korean language class.