This study investigates the order of vowel acquisition in first language (L1) Urdu among infants aged 18 to 36 months in the Pakistani context. The number and classification of Urdu vowels remain debated in previous literature, resulting in limited empirical evidence regarding their developmental sequence. To address this gap, the study adopts an acoustic-phonetic approach to systematically record and analyze vowel production in early childhood. Four Urdu-speaking infants aged 18, 24, 30, and 36 months were selected through purposive sampling, ensuring that Urdu was the primary language used at home. Speech samples were recorded in naturalistic settings using an Android device and analyzed through Praat software. Acoustic analysis focused on formant frequencies (F1, F2, and F3) to identify and verify vowel sounds, which were then compared with standard phoneme charts for validation. The findings reveal a developmental pattern in vowel acquisition: back vowels are acquired earlier than front vowels; long vowels precede short vowels; and low vowels are acquired at later stages. The results contribute to the understanding of phonological development in Urdu-speaking children and provide empirical evidence for vowel acquisition hierarchy in L1 Urdu. This research offers valuable insights for linguists, speech-language pathologists, and early childhood language development studies in the Pakistani context.

L1 acquisition, Urdu phonology, vowel acquisition order

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