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Aims To test the hypothesis that exposure to ambient language in the womb alters phonetic perception shortly after birth. This two-country study aimed to see if neonates demonstrated prenatal learning by how they responded to vowels in a category from their native language and another nonnative language, regardless of how much postnatal experience the infants had. Method A counterbalanced experiment was conducted in Sweden (n=40) and the USA (n=40) using Swedish and English vowel sounds. The neonates (mean postnatal age = 33 hrs) controlled audio presentation of either native or nonnative vowels by sucking on a pacifier, with the number of times they sucked their pacifier being used to demonstrate what vowel sounds attracted their attention. The vowels were either the English /i/ or Swedish /y/ in the form of a prototype plus 16 variants of the prototype. Results The infants in the native and nonnative groups responded differently. As predicted, the infants responded to the unfamiliar nonnative language with higher mean sucks. They also sucked more to the nonnative prototype. Time since birth (range: 7–75 hours) did not affect the outcome. Conclusion The ambient language to which foetuses are exposed in the womb starts to affect their perception of their native language at a phonetic level. This can be measured shortly after birth by differences in responding to familiar vs. unfamiliar vowels.

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Canonical syllables may be important units in early speech perception as well as production. Twenty infants (mean age 51 hours) (and twenty controls) were tested for their ability to discriminate between members of syllable pairs which were either canonical (pæt and tæp) or non-canonical (pst and tsp). A discrimination learning method was used in which syllables signalled the availability of either a recording of the mother's voice or silence – one of which was presented if the infant began a sucking burst. Infants in the canonical condition changed sucking patterns during signals over an 18-minute experimental session and activated their mother's voice more than silence, consistent with previous experiments using mother's voice as a reinforcer. In the non-canonical condition, infants also changed sucking patterns but sucked more during the signal for quiet than mother's voice, contrary to previous findings. Differential sucking during the syllables indicated discrimination in both conditions, but infants responded differently depending upon whether the syllables were canonical or non-canonical. The activation of silence in the non-canonical condition may be the result of a preference for quiet, but it is better explained as a failure to progress to a level of differential responding that was reached by the canonical group.

The prevailing view is that newborn phonetic perception is tabula rasa because of poor transmission of the acoustic features of phonemes to the fetus. However, vowel information may be at least intermittently clear in utero. We tested 80 neonates (M = 32.8 h old, range 7–75) in the US and Sweden with English and Swedish vowels using an infant-controlled sucking procedure. Sucking activated 1 of 17 stimuli (a prototype and 16 variants) from the same vowel category, either the English /i/ or the Swedish /y/. Infants sampled through all 17 stimuli, presented randomly, one time. The dependent measure was mean number of sucks per stimulus. Results showed that the Foreign Vowel Group had significantly greater means to the prototype than the Native Group. A within-group analysis showed another Foreign-Native Group difference. Infants in the Foreign Group had significantly more sucks to the prototype compared to the variants, whereas the Native Group treated the prototype and variants equivalently. These results require us to re-evaluate assumptions about availability of speech sounds to the fetus and the state of speech perception at birth.

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