A cross-language comparison of /d/-/th/ perception: evidence for a new developmental pattern

Area of Science:

• Developmental Psychology
• Linguistics
• Speech Perception

Background:

• Infants typically lose the ability to distinguish non-native speech sounds by 10-12 months.
• This developmental decline suggests an emerging language-specific bias in auditory perception during the first year of life.
• Previous research indicates this pattern holds for many non-native contrasts, especially those relevant to adult language experience.

Purpose of the Study:

• To investigate the perceptual differentiation of the English /d-th/ contrast in English- and French-learning infants and adults.
• To compare developmental patterns of phonetic discrimination with existing models of early language acquisition.
• To examine the influence of language experience on the perception of specific speech sounds.

Main Methods:

• Utilized the conditioned headturn procedure to assess perceptual abilities.
• Tested English- and French-speaking adults.
• Tested English- and French-learning infants at two age groups: 6-8 months and 10-12 months.

Main Results:

• Perceptual differentiation of English /d-th/ was not affected by language experience in infants aged 6-12 months.
• Language experience significantly facilitated performance in differentiating /d-th/ after 12 months of age.
• Infants without specific language exposure showed no change in performance.

Conclusions:

• The study's findings contradict previous research and established theoretical frameworks regarding early language-specific perceptual biases.
• Language experience appears to influence phonetic processing of the /d-th/ contrast later than previously thought.
• Acoustic properties of sounds, phonotactic rules, and lexical development may play roles in these developmental patterns.