Abstract
In tonal languages, voice pitch inflections change the meaning of words, such that the brain processes pitch not merely as an acoustic characterization of sound but as semantic information. In normally-hearing (NH) adults, this linguistic pressure on pitch appears to sharpen its neural encoding and can lead to perceptual benefits, depending on the task relevance, potentially generalizing outside of the speech domain. In children, however, linguistic systems are still malleable, meaning that their encoding of voice pitch information might not receive as much neural specialization but might generalize more easily to ecologically irrelevant pitch contours. This would seem particularly true for early-deafened children wearing a cochlear implant (CI), who must exhibit great adaptability to unfamiliar sounds as their sense of pitch is severely degraded. Here, we provide the first demonstration of a tonal language benefit in dynamic pitch sensitivity among NH children (using both a sweep discrimination and labelling task) which extends partially to children with CI (i.e., in the labelling task only). Strong age effects suggest that sensitivity to pitch contours reaches adult-like levels early in tonal language speakers (possibly before 6 years of age) but continues to develop in non-tonal language speakers well into the teenage years. Overall, we conclude that language-dependent neuroplasticity can enhance behavioral sensitivity to dynamic pitch, even in extreme cases of auditory degradation, but it is most easily observable early in life.
Highlights
The largest differences between these populations occurred for the youngest children: NH Taiwanese behaved relatively adult-like at 6 years of age whereas NH Americans progressively caught up with NH Taiwanese up to 18 years of age, presumably compensating their lack of tonal exposure by cognitive skills
Given the current slope of regression with chronological age, this tonal language benefit would not be observed in adulthood
Despite stringent limitations in F0 coding, growing up in a tonal language environment could help children in reaching a decision with shallow (for NH) or degraded (for CI) pitch contours
Summary
They included 44 Americans with NH (21 of whom had previously been reported32), 53 Taiwanese with NH, 52 Americans with CI (23 of whom had previously been reported32), and 45 Taiwanese with CI. The chronological age of all participants varied from 6.1 to 19.5 years. Age at implantation varied from 4 months to 14 years. A minority of Americans (10) were unilaterally implanted (3 on the left side, 7 on the right), while 45 were implanted on both sides. A majority of Taiwanese (39) were unilaterally implanted (16 on the left side, 23 on the right), while only 6 of them were implanted on both sides. Among the children implanted unilaterally, about half of them had sufficient residual hearing to wear a hearing aid on the contralateral ear. For children with a single implant, ear-foam plugged the contralateral ear and any hearing aid was removed
Published Version (Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have