Musical Training and Improving Speech Prosody Perception and Production in Cochlear Implant Users

 Research Summary:

Cochlear implantation has been found to be extremely effective in allowing otherwise deaf individuals to develop speech comprehension; however there are some constraints to the success of the technology.  The ability of children with cochlear implants to process complex sounds including auditory information is limited, which can negatively affect their ability to communicate at the same level as individuals with normal hearing.  Most cochlear implant users are unable to discriminate pitch, thus their ability to understand prosody in speech is reduced.  Such individuals therefore find it difficult to understand emotional subtext in speech and to distinguish between statements and questions. A lack of prosody comprehension can be even more limiting for individuals who speak tonal languages, such as Mandarin.  If prosody is not perceived, the basic meaning of many words in these languages cannot be understood.

In a 2010 study, Japanese children with cochlear implants were presented with a variety of recordings of words spoken with different emotions.  In each recorded example amplitude, which is an important emotional cue for cochlear implant users, was normalized. In the absence of varying amplitudes, the cochlear implant using participants were unable to identify angry utterances, often confusing them with happy utterances. Previous studies have had similar results, demonstrating cochlear implant user’s challenges in perceiving valence in speech.  The also investigated the production of vocal emotion in cochlear implant users.  Children were instructed to imitate exclamations of emotion and several simulations of animal sounds.  Although the control group with normal hearing performed surprisingly poorly on this test, the cochlear implant users showed significantly more difficulty in imitating prosody.  This suggests that perception of prosody is instrumental in learning prosodic patterns (Nakata, 2010).

Although music therapy is already being used to assist children with cochlear implants in improving their auditory perception, very few studies have been completed to determine its efficacy.  Musical training has been shown to enhance processing of speech prosody in children with normal hearing as it can improve a child’s detection of rhythm and pitch, two vital components of both speech and music.  Several ongoing studies are investigating the benefit of musical training in supporting the development of speech prosody comprehension and production in cochlear implant users.  A study begun in 2009 at the University of Helsinki in Finland is investigating how musical experience affects the prosody perception and speech comprehension in children using cochlear implants. The study is also investigating whether earlier implantation positively affects a child’s musical engagement. Earlier musical engagement may lead to higher success of musical therapy (Torppa, 2009).

A study at the Zürich University Hospital is currently investigating the affect of rhythm training, pitch training, and combined rhythm and pitch training on cochlear implant user’s speech perception.  The project integrates piano playing, singing, and listening training, and is evaluating speech perception through various tests that evaluate emotional perception, pitch-ranking, melody and rhythm differentiation.  The study is also using PET scanning to monitor the cerebral blood flow in different auditory brain areas during and after training.  The authors hope to provide some insight into the development of better postoperative procedures to improve speech understanding in individuals with cochlear implants (Peterson, 2009).

The University of Toronto is collaborating with the Hospital for Sick Children to study the potential benefit of voice lessons for cochlear implant users.  The study integrates individual singing instruction with singing and listening practice. The study may demonstrate whether the development of motor skills involved in the physical production of pitch in combination with ear training will improve pitch discrimination and production (MacDonald, 2011).  

As the success of the cochlear implantation depends on both neuro-plasticity and postoperative therapies, investigating the affect of music therapies in auditory comprehension in conjunction with the therapies’ affect on the brain will be an important step toward understanding the best postoperative procedures. The studies discussed above are the first, small steps toward improvements in treatment of individuals with cochlear implants. 

Reflection:

            The ability to communicate effectively is a vital part of social integration and thus, quality of life.  Cochlear implants provide one step towards helping some hearing impaired individuals communicate with the hearing community.  However, quality of life is still greatly reduced when an individual is unable to express or understand emotional subtext.  In worst possible case, the inability of cochlear implant users to understand prosody could lead to a complete lack of communication, making full social integration extremely difficult. 

In some cases, music therapy is already being used to supplement the natural learning process that occurs after an individual receives a cochlear implant.  However, further research will need to demonstrate its objective value if funding is to be secured in the future.  If preliminary findings suggest music could improve the communicative function of cochlear implant users, further research may be able to develop the understanding of the link between speech and music.  Most importantly, further research may better equip caregivers and therapists to help their clients attain the best possible quality of life.

            If certain pitch contours are associated with specific emotions in each language, could musical training focusing on associating those intervals with each emotion benefit post-operative therapy? Perhaps there are musical genres or composers that innately used those prosodic pitch forms in their music to communicate emotion. Does the use of these forms contribute to how our emotions are affected by music?  Not only would further research in this area benefit cochlear implant users, but it would also provide significant insight for understanding music.  

Works Cited:

MacDonald, Lorna, Taylor Hopyan, and Karen Gordon. "Cochlear Implant Singing Study." The International Symposium on Performance Science Proceedings (2011). Print.

Nakata, Takayuki, Sandra E. Trehub, and Yukihiko Kanda. "Effect of cochlear implants on children's perception and production of speech prosody." Journal of the Acoustical Society of America 131.2 (2010): 1307-14. Web. 13 Nov. 2012.

Peterson, Bjorn, Malene V. Mortensen, Albert Gjedde, and Peter Vusst. "Reestablishing Speech Understanding through Musical Ear Training after Cochlear Implantation: A Study of the Potential Cortical Plasticity in the Brain." The Neurosciences and Music 1169 (2009): 437-40. Web. 13 Nov. 2012. <https://pure.au.dk/portal/files/18130979/Nyas_artikel_final.pdf>.

Torppa, Rivta, Miika Järvenpää , Minna Huotilainen, Andrew Faulkner and Martti Vainio. "Music related speech perception abilities in children with cochlear implant devices; does music involvement affect other auditory domains?" Frontiers Neuroscience Conference Abstract: Tuning the Brain for Music (2009). Web. 13 Nov. 2012. <http://www.frontiersin.org/10.3389/conf.neuro.09.2009.02.030/event_abstract>.