April 2019 ASHAWire
Music, like human language, is one of the most complicated, demanding, yet unique human activities. Music events, including both instrumental and vocal performance, use the basic elements of pitch, rhythm, loudness, and timbre to convey information. Vocal music performance, simply called singing, is universal to all cultures and regions. Singing plays important communicative, social, and religious roles throughout human history. For people with hearing impairments, due to the damaged peripheral or central auditory system, their music processing and vocal singing show varying degrees of deficits.
The contemporary multichannel cochlear implant (CI) bypasses the injured part of the inner ear and directly stimulates the auditory neurons electrically. This device conveys adequate information for speech recognition and precise rhythmic information for music perception, which helps people with severe-to-profound sensorineural hearing loss restore partial auditory sensation and greatly improves their communicative abilities. However, because pitch information is not explicitly encoded in CI stimulations, pitch-related tasks in music and speech (e.g., lexical tone, intonation, voice, and emotion recognition) are still challenging for CI users.
A group of 10 prelingually deafened children with cochlear implants (CIs) formed a choir and received 21 months of formal music training. The purpose of this study was to evaluate the singing proficiency of these children. The participants included all choir members (7 girls and 3 boys, mean age of 9.5 years old) who were unilateral CI users. Meanwhile, 8 age-matched children with normal hearing were recruited as controls and were trained on 1 song for 2 weeks. Individual singing samples without instrument accompaniment were recorded from all participants. The singing samples were subject to acoustic analysis in which the fundamental frequency (F0) of each note was extracted and the duration was measured. Five metrics were developed and computed to quantify the accuracy of their pitch and rhythm performance. The 5 metrics included (a) percent correct of F0 contour direction of adjacent notes, (b) mean deviation of the normalised F0 across the notes, (c) mean deviation of the pitch intervals, (d) mean deviation of adjacent note duration ratio, and (e) mean absolute deviation of note duration.
The choir members with CIs demonstrated high accuracy in both pitch and tempo measures and performed on par with the children with normal hearing. Early start of music training after implantation and use of bimodal hearing contributed to the development of better music ability in these children with CIs. These findings indicated that rigorous music training could facilitate high singing proficiency in prelingually deafened children with CIs.