Music to the Impaired or Implanted Ear

Music With a Cochlear Implant : A Personal Perspective

by Kate Gfeller and John F. Knutson

Music is a ubiquitous art form found within every known culture. Although music is not considered essential for survival, Americans spend billions of dollars annually on concerts, recordings, and musical instruments. We use music to soothe our infants and delight our toddlers. We use music to foster social affiliation, celebration, and romance. Since the earliest days of cinematography, filmmakers have employed music to convey the emotional tone or key message of movies. We mark the most significant events of our lives (graduation, weddings, funerals, etc.) with music, and join in song to express social protest or national pride.

Music is a powerful form of communication that connects us with our families, our friends, and our culture. Because music is so prevalent within society, music is likely to be a part of the everyday environment of people who use hearing aids or cochlear implants. Therefore, the extent to which users of assistive hearing devices can accurately perceive and enjoy music is of practical interest.

How Well Do Hearing Aid Users Perceive and Enjoy Music?

Although both speech and music can be described as having the elements of frequency (referred to in music as pitch  ), spectral variations ( timbre or tone quality ), and duration ( rhythm ), there are differences in these two auditory signals that can have important implication for users of assistive hearing devices.

People with mild hearing losses—and especially those who receive adequate amplification—can hear pitch, melody, harmony, rhythm, and timbre quite effectively. As hearing loss becomes more severe, these elements become more difficult to perceive, not only due to audibility factors, but also to signal distortions that may be introduced by the hearing-impaired ear. Therefore, recognizing melodies or appreciating harmony is harder for persons with severe losses. They can, however, appreciate the rhythm of music, in part because they can sometimes "feel" the beat through vibrotactile means. In particular, people who use cochlear implants (CIs) do not receive as normal a representation of pitch as do those who use hearing aids.

Some hearing aid users describe music as sounding the same or similar to what is heard by normal hearing listeners, while others may find that music sounds harsh or shrill, empty or dull. This variability is not surprising to audiologists who are well aware of the range of satisfaction among hearing aid users and the many factors that influence hearing aid benefit for many types of sounds.

As with speech recognition, the quality and enjoyment of music is generally affected by the type and degree of hearing loss. Importantly, however, the frequencies that are salient for music perception and enjoyment encompass a much greater range than required for speech perception; commonly heard musical instruments can play notes with fundamental frequencies as low as approximately 25 Hz to as high as approaching 18,000 Hz (and even higher harmonics).

Because the sound quality may be distorted in part or all of the frequency range, mere amplification may not be adequate for the hearing aid user to appreciate the entire range of the music spectrum, both in terms of loudness and pitch. Although the percept delivered by a CI differs considerably from that offered by hearing aids, recent research on music listening by implant users could have implications for aural rehabilitation efforts with hearing aid users as well as implant users.

How Well Do Cochlear Implant Recipients Perceive and Enjoy Music?

Contemporary CIs have been designed primarily to transmit sounds that are important for speech recognition. Thus, the implant does not transmit a replica of musical sound as we hear it through a normal ear, though it does provide a fairly normal representation of rhythm. Studies conducted at the Iowa Cochlear Implant Clinical Research Center (University of Iowa Hospitals and Clinics, department of otolaryngology) show that many people who use CIs perceive the rhythm of music, or the "beat," very well. This might explain, in part, why some implanted teenagers say they prefer rap music, which consists chiefly of rhythmically spoken lyrics over a steady beat, or why some of our adults report enjoying line dancing to music with a prominent and steady beat.

Although implant recipients can generally differentiate the sound of one musical instrument from another, they may not be able to identify the instrument they are hearing by sound alone as easily as children or adults who have normal hearing. However, some implant recipients are able to learn what the instruments sound like through listening practice in which they can see the picture or name of the musical instrument while they listen to the instrument’s sound.

More importantly from the standpoint of listening enjoyment, the tone quality of some musical instruments may sound unnatural or tinny, especially for some instrument types or those in higher frequency range. Because there is considerable difference from one CI user to the next, some experimentation is in order to determine preferences of individual users, the factors that influence those preferences, and how those factors might be used in an auditory rehabilitation process.

Probably the most difficult aspect of music listening for many implant recipients is identifying how low or high the pitch is. Rather than hearing the melody like people with normal hearing, some implant users may perceive a melody as a random series of pitches. Musical tasks such as recognizing a melody from pitch alone (no lyrics) is very difficult for many implant recipients. For example, many CI users have difficulty recognizing or singing melodies, even those of familiar childhood songs such as "Happy Birthday" or "Frère Jacques." However, with practice, some implant recipients can learn to recognize such common songs, in part by following the rhythmic pattern of the song or by listening to the lyrics.

Keep in mind, however, that implant recipients vary considerably on how well they can perceive pitch. Some implant recipients do remarkably well and can perceive fairly small pitch differences. Others with the same device or processing strategy have enormous difficulty perceiving pitch changes with any degree of accuracy. We don’t yet fully understand why the differences are so great from one implant recipient to the next, but there are a number of factors we think may contribute to the differences. These include the relative health of the auditory nerve, the cause of deafness, whether a full insert of the implant was possible, whether all the implant channels are active, the age at implantation, cognitive and perceptive abilities, and listening experiences, to name a few.

To some extent, a person with impaired hearing such as an implant recipient must learn to use a degraded acoustic signal. For that reason, it is clear that practice and repeated exposure to musical stimuli can play an important role in determining how effectively a person can use music and how much enjoyment the individual might receive from musical experiences.

Thus, factors that influence exposure to music and use of music can be important in determining ultimate use and ultimate pleasure. From our work with implant users, it is clear that although not all implant users develop an appreciation for musical experiences, from those who do, active engagement in musical listening is a prerequisite for enjoyment. An aural rehabilitation program then needs to consider ways to enhance exposure and engagement when the initial benefits might be limited. One strategy that might be considered would be active music participation rather than only listening.

Related to the problem of perceiving pitches and recognizing melodies is singing or playing an instrument along with others. Even some of the most successful implant recipients in our center tell us that they find it very difficult to sing along with or tune an instrument to an external pitch. Consequently, some implant recipients who enjoy singing report that they prefer to do so alone, rather than as part of a choir. However, we have found that some children enrolled in our implant center enjoy singing and continue to participate in choir in school as long as they feel comfortable. Our adult implant recipients seem a bit more self-conscious about singing, indicating that they may sing exclusively in the privacy of their own home. Instruments that require precise and ongoing tuning, such as the violin, may be extremely difficult for most implant recipients to play.

Social Considerations

The social aspects of music may be important to consider in the aural rehabilitation process. While some persons with impaired hearing are not willing to perform in the presence of others, that experience is not unique to those with hearing impairments.

Musical listening experiences, however, are often a central aspect of the social fabric. Consequently, the social aspects of musical listening are worth considering. Indeed, diary and self-report data we have obtained indicate that it is the social aspects of listening that are often missed by persons with profound or severe hearing loss. Importantly, spouses of these individuals report engaging in fewer positive social events, including musical events, than a comparison sample whose spouses have normal hearing.

Despite the limitations of current-day devices in transmitting musical sounds, it is interesting to note that many adults and children with implants do participate in and enjoy music. For example, in our own center, 73% of the children are involved in music at school or at home. However, the extent of enjoyment and success seems to depend more heavily on the listening environment (e.g., a noisy room is particularly bad for music listening) and the type of music (i.e., simple and repetitive) than is the case for normally hearing children.

In developing musical listening experiences for implanted clients, it is important to recognize that children with implants differ from adult implant recipients in an important way. While most adult implant recipients will be able to compare their musical percept through the implant with their memory and mental image for "normal" musical sounds, children who mature with implants have learned about music through the implant, a device that does not represent pitch or timbre in a completely normal way.

Thus, such children cannot use contextual cues and past memories of music to make sense of the musical sound. However, on a positive note, because these children have grown up hearing music through an implant and consider that sound "normal," they may be less critical than adult implant users about the sound quality and find music pleasant in a unique way.

Acoustic Environment

The particular listening environment also can make a difference for both hearing aid and implant users. Just as in speech-listening tasks, rooms with hard floors, no curtains, many windows, or few materials to absorb sound also will increase reverberation and may cause additional distortion to sound. A great deal of background noise or poor sound equipment also may interfere with music enjoyment.

Individual Differences

Although there are wide variations among implant users in their ability to use music and their capacity for enjoyment, our research suggests that such variation is not random. Importantly, some of the cognitive predictors that predict speech perception with an implant also predict the accuracy with which some musical information is perceived. We have also found that speech perception ability is not necessarily a good predictor of some facets of musical perception. Thus, aural rehabilitation specialists cannot assume that good speech perception will automatically translate into good music perception.

Individual Preferences

Children and adults are not only influenced by their hearing loss and the listening environment, but also by their social environment. Children tend to be influenced by the attitudes of their friends and the media, especially in the teen years. Of course, adult engagement in musical events can be influenced by the social context. Importantly, among married subjects, a supportive spouse can play an important role in gaining benefit from an assistive device. Furthermore, all human beings have their own personal music preferences for specific songs, artists, or styles. A musical component for auditory rehabilitation cannot be a "one-size-fits-all" approach.

Music Activities to Consider

There are four basic types of music activities that children and adults can enjoy at school or at home: listening, moving, singing, and playing. Below are a few examples of each.

• • Listening to Music.  Music is pervasive. We hear it in the car, during movies and television programs, and as the primary focus of listening to CDs, watching music videos, and attending concerts. In movies, such as Lilo and Stitch or The Lion King, the visual images of the videos can help the listener with a hearing impairment make sense of the dialogue and the music.
  
  Older children and adolescents are much more likely to listen to music for its own sake, in isolation and in group settings. In many cases, the music is not just sound, but also an opportunity for social connection. The lyrics and dominant rhythmic beats in pop music can help children to gain some enjoyment. Listening to music also offers an opportunity to practice speech recognition in a fun and novel way. By exploring various kinds of music and listening circumstances, children may discover music that is meaningful to them.
  
  • Moving to Music. Some children and adolescents may enjoy moving or dancing to music. Moving may include participation in a marching band or an aerobic exercise class. Some children enjoy formal dance instruction, such as tap, ballet, or jazz. Because the beat of the music is generally effectively transmitted through the hearing aid or implant, teenagers can participate readily in social dancing to pop music or group dances, such as country line dancing. In that context, when the impact of hearing loss on the social activities of adult couples is considered, couples who enjoyed dancing and music prior to experiencing the hearing loss might be encouraged to try dance as a means of increasing social participation and expanding their listening experiences.
  
  • Singing. Singing is one type of music activity that will be considerably influenced by the type and severity of hearing loss, as well as the assistive hearing device. For example, children and adults with severe and profound hearing losses, and especially those who use implants, may find it difficult to match the pitch of their own voice with an external pitch (e.g., a note on the piano or other singers). However, there are still activities that may be enjoyable for some children, such as rhythmic chants (e.g., "Going on a Bear Hunt"). Furthermore, some children may spontaneously choose to sing. It doesn’t matter if they sing the melody perfectly. Singing gives children an opportunity to explore the range of their voice and articulation of speech sounds.
  
  • Playing Musical Instruments. Many people with hearing losses enjoy playing musical instruments. In choosing the most appropriate instrument, take into account the hearing loss and personal preference of each person. For those with more severe hearing losses or who use implants, instruments that require less pitch perception and tuning may be more appropriate. For example, instruments such as drums, the piano, or instruments that change notes by using keys (such as the saxophone or clarinet) can be easier than instruments that require ongoing tuning (such as the violin or trombone).
  
  Older children and teenagers may want to participate in a school band or orchestra. Some people also like to play musical instruments at home, such as the guitar or the piano. Discuss any necessary accommodations for the educational setting with the child’s teachers.

In conclusion, music can be a meaningful and satisfying art form for many people who have some degree of hearing loss. Audiologists can play an important role in optimizing musical enjoyment by providing useful information, by fostering realistic and personally appropriate expectations, and by guiding their clients in the selection of the most suitable and satisfying types of musical activities.

We wish to acknowledge important contributions to this text by Carol Olszewski and Beth Macpherson of the Music Perception Project, Iowa Cochlear Implant Clinical Research Team, The University of Iowa Hospitals and Clinics.

Kate Gfeller is F. Wendell Miller Distinguished Professor in the School of Music and the department of speech pathology and audiology at The University of Iowa. She directs the Music Perception Project for the Iowa Cochlear Implant Clinical Research Center, University of Iowa Hospitals and Clinics, and also directs the Music Therapy Program at the University of Iowa School of Music. Contact her by e-mail at kay-gfeller@uiowa.edu .

John F. Knutson is a professor in the department of psychology at The University of Iowa. He has conducted research on psychological factors in cochlear implant use and outcome in the Iowa Cochlear Implant Clinical Research Center since 1980. In addition, he conducts research on the social development of young children. Contact him by e-mail at john-knutson@uiowa.edu .