Covert contrast as a developmental stage in L2 phonology: evidence from Arabic emphatics

This study examines covert contrasts—acoustically distinct yet imperceptible phonemic differences—in English-speaking learners of Modern Standard Arabic, focusing on /tˤ/–/t/ and /sˤ/–/s/. These contrasts, unique to Arabic, pose acquisition challenges for English-speaking learners. This mixed-methods study combined native-speaker perceptual ratings with acoustic analyses to identify learner-produced covert contrasts. Nearly half of participants exhibited covert contrast in at least one phonemic pair, with fricatives more common than stops. The findings confirmed covert contrast as a systematic stage in L2 phonological development, strongly associated with the amount of formal instruction rather than mere exposure. Acoustic cues (vowel formant shifts, voice onset time) provided measurable evidence of learners’ phonological differentiation even when unperceived by native listeners. Additionally, participants with overt contrast (vs. covert) exhibited greater perceptual accuracy, although production–perception relationship remained asymmetrical. These results highlight the value of integrating instrumental methods into L2 phonological assessment and enhance our understanding of contrast acquisition in L2 learning.