Cross-cultural adaptation and psychometric assessment of a Persian version of Proctor's developmental vocal assessment protocol: Description of Persian infant vocal development

Objectives: With increasing recognition of the importance of pre-linguistic vocalization, and early intervention for children, proper protocols play an important role in documenting infants' progress and effects of early interventional programs. This study aimed to translate Proctor's Developmental Vocal Assessment Protocol into Persian, make cultural adaptations, assess Persian version of Developmental Vocal Assessment Protocol (P-DVAP)'s validity, internal consistency, and reliability, and provide a general perspective toward Persian infants' vocal behaviors.

Methods: This study was mainly conducted in reference to Beaton's guidelines included translation, synthesis, back-translation, expert committee review, & pretesting. Ten well-experienced speech and language therapists contributed in expert committee review. Mothers of 202 infants were interviewed by experienced speech and language therapists.

Results: Expert committee pointed out some difficulties that parents might have responding to P-DVAP. Such difficulties were sorted out in the P-DVAP applied for psychometric analysis. The Content Validity Index and Content Validity Ratio of P-DVAP were above 0.9. In test-retest reliability, Kappa coefficient was 0.6 and as the measure of inter item consistency, Kuder-Richardson-20 for each stage ranged from 0.1 to 0.5. Parents of typical infants reported variations in crying, vegetative sounds, laughing, prosody changes, babbling, approximants of meaningful words, and consonant-vowel structures as the most common vocal behaviors. The number of vocal behaviors reported for preterm infants after corrected gestational age was fewer than those of typical full-term infants.

Conclusion: The P-DVAP is a comprehensive, reliable, valid, simple and clear protocol for clinical evaluation of Persian infants' vocal behaviors.