Impact of Perceptual Training on Comprehensibility in Spontaneous Speech

The ultimate goal of learning to speak a foreign language is to be understood that is, to achieve comprehensibility (Derwing & Munro, 2015). There is strong evidence that training focused on the pronunciation of individual sounds, such as High Variability Phonetic Training (HVPT), improves learners’ ability to identify individual phonemes (Logan et al., 1991; Bradlow et al., 1997) and produce more intelligible speech at the word and sentence level (Thomson, 2011; Iino, 2019). Recent research also suggests potential gains in comprehensibility, though primarily in semi-controlled tasks, leaving it unclear whether such training benefits extend to spontaneous speech, issues that have rarely been examined through delayed testing.

This study investigated the impact of HVPT on perception, intelligibility, and comprehensibility in spontaneous oral production among Chinese learners of English with a focus on high functional load phonemic contrasts. It explored whether improved perception would transfer to word-level intelligibility and, ultimately, to greater comprehensibility in free oral production. A secondary aim was to assess the durability of these gains through delayed testing. HVPT was delivered entirely online, reflecting real-world learning contexts.

Fifty-one adult Mandarin speakers of English completed 15 HVPT lessons over three weeks. A pre-, post-, and delayed post-test design assessed perception via identification tasks, intelligibility through a read-aloud task, and comprehensibility via both semi-controlled and spontaneous speech. Results showed significant and sustained improvements in phonemic perception. Intelligibility gains were modest and varied by phoneme, while comprehensibility improved notably in the spontaneous narrative task, but only at delayed post-test. These patterns suggest a time-dependent transfer from perception to production.

Overall, the findings highlight HVPT’s potential to support long-term L2 speech development. Gains in perception can cascade into improvements in intelligibility and comprehensibility, particularly when diverse speaking tasks and delayed assessments are used. The study underscores the value of integrating spontaneous speech and longitudinal evaluation into pronunciation research and pedagogy.