Cochlear implant has helped thousands of patients with profound sensorineural hearing loss to gain hearing and speech recognition. In current designs of cochlear implants, however, pitch information of complex sounds is limited. This imposes a special challenge for patients who speak tone languages, such as Mandarin Chinese. The purpose of the proposed study is to investigate tone acquisition in the increasing number of Mandarin-speaking children with cochlear implants using a prospective, longitudinal research design. Since there are only scarce normative data on Mandarin tone acquisition, we will first establish a database to which the tone acquisition data from children with cochlear implants can be compared.
In Specific Aim 1 of the proposed study, 30 normal-hearing, native Mandarin-speaking children will be recruited at age of 6 months and followed up till 3 years of age. The speech samples will be recorded at intervals of 4 - 6 weeks in the period of 2.5 years.
In Specific Aim 2, 30 native Mandarin-speaking children (1 - 18 years old) with cochlear implants will be recruited and the speech samples will be recorded at intervals of 4 - 6 weeks from 6 months to 3 years after activation. Both groups of subjects will be recruited from Beijing, China. The recorded speech materials will be subject to acoustic, neural-network, and perceptual analyses that we developed previously. The acoustic analysis will focus on the fundamental frequencies (F0) of the speech tokens, especially the onset and offset F0 values. The neural network analysis will be used to provide an objective measure of tone production accuracy. The perceptual tests in which normal-hearing, native Mandarin-speaking adults (N= 10) will perform tone recognition on the syllables produced by the children will provide a subjective measure of tone production accuracy. To construct the developmental trajectories of tone acquisition, the longitudinal outcome measures of tone production will be plotted as a function of age for the normal-hearing children or duration of implant use for the children with cochlear implants. Multiple regression analyses will be performed to identify any associations of age at implantation and duration of implant use with the tone production measures. Although the proposed study is primarily concerned with lexical tone production, it has important implications for speakers of non-tonal languages. A better representation of pitch information would be useful in identifying and separating multiple talkers and providing music perception for cochlear-implant users. Therefore, the proposed study could improve quality of life for many cochlear implant users.
Cochlear implants provide good speech recognition to patients with profound hearing loss but fail to deliver pitch information to the users. The proposed study will carry out a longitudinal evaluation of tone production in prelingually-deaf children who have received cochlear implants and will determine how tone develops with such insufficient pitch information. This research will advance our knowledge of tone development and enhance rehabilitation of cochlear implant users. ? ? ?
