The Discrimination of Vowels and Consonants

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

2. 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

3. 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.

4. 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.

5. 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].

6. 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)

7. 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

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

9. 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].

10. 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).

12. 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 5-17 weeks old can discriminate them.