The Discrimination of Vowels and Consonants by Lara Lalonde, Jacynthe Bigras, Jessica Flanagan, Véronick Boucher, Janie Paris & Lyzanne Cuddihy

Based on 2 articles The Discrimination of Foreign Speech Contrasts by Infants and Adults – By Sandra E. Trehub, 1976 Simultaneous Bilingualism and the Perception of a Language-Specific Vowel Contrast in the First Year of Life – By Laura Bosch and Núria Sebastián-Gallés, 2003

Previous Research Very young infants are better able to perceive phonetic distinction than adults. By the end of the first year of life, infants’ responsiveness to many non-native contrast will be significantly reduced. (Aslin, Pisoni, & Jusczyk 1993 and Jusczyck 1997) Only a few studies have described developmental changes in vowel perception. – Language specific effects seem to be present earlier for vowels than consonants, at around 6 to 8 months of age.

Previous Research (cont): Polka and Werker (1994) found that 4 month old infants can discriminate a pair of foreign vowel in a /dVt/ context. At 6 to 8 months of age, this pattern was already modified and by 10 to 12 months of age, infants were no longer able to discriminate foreign vowels.

Trehub’s Article Introduction: This study looks at how infants between 5-17 weeks of age could discriminate foreign language contrasts. Trehub conducted 2 experiments to evaluate this phenomenon in infants. – She observed the nasal vowel distinction [pa] vs [pã] and the distinctive feature of stridency [  a] vs [  a].

Subjects: Residents of Montreal, Canada English as a home language. 40, full-term, healthy infants – 20 in experiment 1 (~ 10.5 weeks old) – 20 in experiment 2 (~ 9.5 weeks old)

Stimuli: Experiment 1 used stimuli [pa] vs [pã] from the French and Polish languages. – ~500 ms in duration Experiment 2 used stimuli [  a] vs [  a] used by Czech speakers. (feature of stridency) – ~500 ms in duration

Apparatus Nonnutritive sucking was attached to a pressure transducer which transcribed the results on a polygraph.

Procedure: [pa] or [  a] was presented to both experimental and control groups in the habituation phase. decrement criterion: decreased sucking rate at least 33 1/3 % below the infant's highest rate, maintained for 2 consecutive minutes. when the decrement criterion was reached, the contrast stimulus was substituted for the experimental group only: [pã] or [  a].

Results Consisted of criterion sucks per minute No significant differences in the predecrement period (before switch) for both the experimental and control group. Significant differences in postdecrement period (after switch).

Discussion Infants are able to discriminate between pairs of foreign language contrasts that they have never heard before. Even if the nasal vowel [ã] and the strident consonant [  ]  are said to be among the latest productive acquisitions for speakers of relevant languages, infants aged between weeks old can discriminate them.