Vocal matching in interactions between mothers and their normal-hearing and hearing-impaired twins

Abstract

Vocal matching, the ability to imitate phonetic properties of speech, was examined in interactions between mothers and their normal-hearing (NH) and hearing-impaired twins who used hearing aids (HAs) or a cochlear implant (CI). Vocalizations of three mother-twin triads were recorded in three sessions over 12 months. In one triad, the twins were 15.8 months old and NH. In another triad, the twins were 11.8 months; one was NH while the other had HAs. In the third triad, both twins were 14.8 months; one was NH while the other had a CI. A vocal match was defined as an instance of perceptual and acoustic similarity between adjacent maternal and infant utterances in relation to pitch height and contour, utterance duration, rhythm, or vowels and consonants. Reciprocal vocal matching occurred in 28% to 38% of infant vocalizations across triads. At session three, CI and HA infants’ reciprocal vocal matches increased compared to two previous sessions and to those of NH siblings; reciprocal vocal matches in the NH dyad decreased over time. The results suggest that vocal matching is a part of linguistic interactions between mothers and their NH and HI infants and that pediatric hearing loss affects mothers’ and infants’ imitative abilities.