This story, out of Israel, touches on the uses of music therapy with children using cochlear implants, devices that allow children with sensorineural hearing impairments to hear. While cochlear implants are immensely useful, they do require an adjustment period. Imagine being able to hear nothing one day, and then almost everything the next. It is important to note that hearing with cochlear implants is different than typical hearing. The perception of music is very different, as folks with cochlear implants are generally unable to differentiate small changes in pitch and timbre, simply because of the nature of the device. Rhythmic perception, however, is generally uncompromised.
As one might guess, the ability to hear plays a monumental role in language development. In the study referenced in this news article, music therapy resulted in increased spontaneous and nonverbal communication. In other approaches, music therapists use the rhythmic properties of music to reinforce syntax and inflection, as well as other structural elements of spoken language. Music therapists also use music to reinforce community and acceptance.
There is a very comprehensive chapter about music therapy with hearing loss in Music in Special Education