Developmental trends in voice onset time: some evidence for sex differences

Area of Science:

• Linguistics
• Developmental Psychology
• Phonetics

Background:

• Voice onset time (VOT) is a crucial acoustic cue for distinguishing voiced and voiceless consonants.
• Understanding the developmental trajectory of VOT in children is essential for tracking speech acquisition and identifying potential speech sound disorders.
• Previous research suggests potential sex differences in phonological development, but comprehensive data on VOT across different ages and consonant types in children is limited.

Purpose of the Study:

• To investigate age and sex-related differences in voice onset time (VOT) patterns for the plosives /p, b, t, d/ in children aged 7, 9, and 11 years.
• To examine whether sex differences in VOT become more pronounced with age and approach adult-like values by 11 years.
• To determine if the magnitude of age and sex differences in VOT varies depending on the specific plosive consonant.

Main Methods:

• Participants included 30 children (15 boys, 15 girls) evenly distributed across three age groups: 7, 9, and 11 years.
• Children produced target plosives /p, b, t, d/ in syllable-initial position with a consistent vowel context by naming letter objects.
• Voice onset time (VOT) was acoustically measured and analyzed for differences based on age, sex, and consonant type (voiced/voiceless cognates).

Main Results:

• VOT values for /p, b/ generally decreased with age in boys, while /t/ VOT showed some increase in girls.
• A more distinct bimodal distribution differentiating voiced and voiceless cognates was observed in girls' VOT patterns.
• Marked sex differences in the voiced/voiceless VOT contrast emerged between 9 and 11-year-olds, especially for alveolar plosives (/t, d/).

Conclusions:

• The study's findings support the hypotheses that sex differences in VOT exist in preadolescent children and become more marked with age.
• These developmental and sociophonetic patterns suggest that by age 11, children exhibit more adult-like VOT distinctions, with variations across consonant types.
• The results highlight the interplay of age, sex, and phonetic context in shaping the acquisition of phonological contrasts.