Acoustic properties of vowel production in prelingually deafened Mandarin-speaking children with cochlear implants

Abstract

The present study examined the acoustic features of vowel production in Mandarin-speaking children with cochlear implants (CIs). The subjects included 14 native Mandarin-speaking, prelingually deafened children with CIs (2.9-8.3 yr old) and 60 age-matched, normal-hearing (NH) children (3.1-9.0 years old). Each subject produced a list of monosyllables containing seven Mandarin vowels: [i, a, u, y, ɤ, ʅ, ɿ]. Midpoint F1 and F2 of each vowel token were extracted and normalized to eliminate the effects of different vocal tract sizes. Results showed that the CI children produced significantly longer vowels and less compact vowel categories than the NH children did. The CI children's acoustic vowel space was reduced due to a retracted production of the vowel [i]. The vowel space area showed a strong negative correlation with age at implantation (r = -0.80). The analysis of acoustic distance showed that the CI children produced corner vowels [a, u] similarly to the NH children, but other vowels (e.g., [ʅ, ɿ]) differently from the NH children, which suggests that CI children generally follow a similar developmental path of vowel acquisition as NH children. These findings highlight the importance of early implantation and have implications in clinical aural habilitation in young children with CIs.

Mandarin compound vowels produced by prelingually deafened children with cochlear implants

“…Consistent with previous studies [15,39], the present study showed that the CI children produced all compound vowels with longer duration than the NH peers, which suggested that the CI children may need more time to form the articulatory gestures and to travel from one target to the other. Earlier research on NH speakers reported that lengthened vowel duration and greater formant frequency change corresponded to higher speech clarity [40].…”

“…In addition to the comparison of relative position defined by F1 and F2 between the NH and CI children, a measure of overall acoustic distance was calculated to show the potential positional deviation of the CI children relative to NH targets. Following the procedure described in Yang et al [15], for each vowel, the mean F1 and F2 were calculated for each measurement point in the NH children. Then, the Euclidean distance between each participant and the NH target was calculated for each measurement point.…”

“…While numerous studies have examined speech perception of the CI users, only a few studies have focused on their speech production, in particular, development of vowel and consonant inventory [1-7]. A number of acoustic studies were undertaken to examine the basic acoustic features of selected monophthongal vowels in CI children [8-15]. There was a consensus regarding the facilitating role of implantation on the acoustic development of vowel production in the hearing-impaired children.…”

“…There was a consensus regarding the facilitating role of implantation on the acoustic development of vowel production in the hearing-impaired children. However, it remained controversial in whether the CI children could reach the age-matched norms in the detailed acoustic-phonetic characteristics [8,14,15]. Unlike monophthongs that involve one articulatory position, diphthongs have two distinct articulatory targets connected by a marked transition within one syllable [16].…”

Effects of nonlinear frequency compression on the acoustic properties and recognition of speech sounds in Mandarin Chinese

“…First, the F1 and F2 values were converted to their respective z-scores following the Lobanov's method (Lobanov, 1971). The zscores were then rescaled back to Hz-like values following Thomas and Kindle (2007) to facilitate comparison and interpretation (see also Yang et al, 2015).…”