A Phonetic Study of L1 Influence on Production and Perception of English Diphthongs in Pakistani English: A World Englishes Perspective

In this paper, L1 phonemic systems are discussed in the context of their impact on the pronunciation and perception of English diphthongs in PE, drawing on World Englishes and phonetic analysis. The study focuses on speakers whose native languages are Punjabi, Seraiki, Pashto, and Urdu, and examines how changes in local vowel inventories and glide processes influence diphthong production. The controlled production and perception tasks were done on eight English diphthongs by 40 adult speakers (10 speakers per L1 group). The formant trajectories (F1, F2), duration, and intensity were recorded by acoustic analyses, which are used to measure the variation that occurs as the articulatory glide occurs between vowel targets. Perception was measured using diphthong identification tasks to assess listeners’ sensitivity to dynamic spectral movement. The results indicate systematic L1-conditioned restructuring. Deviations were the most pronounced in diphthongs with significant vowel gliding, especially centering diphthongs, characterized by a decrease in spectral movement, a constriction in vowel space, and a general tendency toward monophthongization. Closing diphthongs were generally more stable in production; however, they still exhibited systematic L1-conditioned variation, particularly in glide magnitude, spectral direction, and temporal realization. These patterns of production were highly consistent with the results of perceptual production: the diphthongs with lesser acoustic movement were also found to be less accurately recognized, and diphthongs in their L1s and speakers of phonemically richer vowel systems had partial glide contrasts. The findings demonstrate that the variation in diphthongs in PE is systematic, reflecting predictable relationships between the L1 phonemic system, perceptual assimilation, and sociolinguistic experience. The findings highlight the pedagogical value of L1-sensitive pronunciation instruction and contribute to the phonetic description of Pakistani English as a systematic contact variety.