Is prosodic production driven by lexical development? Longitudinal evidence from babble and words

Area of Science:

• Linguistics
• Developmental Psychology
• Phonetics

Background:

• Prosodic prominence plays a crucial role in speech perception and production.
• Early phonetic development in infants is influenced by both babbling and word learning.
• Understanding the interplay between lexical development and prosody is key to explaining early language acquisition.

Purpose of the Study:

• To investigate the relationship between lexical development and the emergence of prosodic prominence in disyllabic babble and words.
• To analyze how infants differentiate syllables in disyllabic utterances as their vocabulary expands.
• To explore the role of phonetic patterns in early word production and their connection to vocabulary size.

Main Methods:

• Longitudinal analysis of monthly recordings from nine typically developing infants.
• Measurement of fundamental frequency (f0), intensity, and duration in disyllabic babble and words.
• Tracking vocabulary size from babbling onset up to 200 words.

Main Results:

• The trochaic prosodic pattern, common in the ambient language, emerged in infant babble and became more pronounced in words.
• Words exhibited greater prosodic differentiation in f0 and intensity compared to babble.
• Vocabulary size correlated with more evenly timed syllables in infant word production.

Conclusions:

• Lexical development significantly shapes the production of prosodic prominence in infants.
• Enhanced prosodic features in early words may serve a phonetic highlighting function, aiding word recognition.
• Findings support lexicalist accounts of phonetic development, suggesting a bidirectional influence between lexicon and phonetics.