Vishakha W. Rawool, PhD, is a member of the faculty in the Department of Speech Pathology and Audiology at West Virginia University, Morgantown, WVa.


Cochlear implant (CI) technology can be a viable option for families who are planning to use only sign language with their children or for adults who exclusively communicate through sign language. In Part 1 of this article (see last month’s HR), several potential benefits of CIs, including access to soundscapes, warning sounds, relief from tinnitus, and improvement in quality of life, were reviewed. In the current article, literature related to access to music through CIs is reviewed.

General Benefits of Music

Music appears to exert direct physiological effects through the autonomic nervous system. It is an integral part of religious ceremonies in most cultures and may enhance the spiritual experience for many individuals. Therefore, music has been used to enhance well-being, reduce stress, and distract patients from unpleasant symptoms.1

Investigators have identified several other benefits of music, a few of which will be mentioned here. Many studies suggest that music may promote cognitive abilities, and the evidence for the effect of music training on spatial-temporal reasoning appears to be strong. For example, one study compared math skills of two groups of children.2 The experimental group received piano keyboard training and used math video game software designed to teach fractions and proportional math. The control group received only the math software. The experimental group scored significantly higher on proportional math and fraction tests than the control group.

Some investigators have attributed the effect of music on cognitive activities to changes in a listener’s arousal and mood.3 The degree of arousal is dependent on the intensity of the felt emotion. Faster musical tempi are generally more arousing than slower musical tempi. Mood is determined by whether the emotion is positive or negative.

In one study, undergraduate students performed better on an IQ subtest after listening to an up-tempo piece of music composed by Mozart compared to a slow piece by Albinoni. The effect was apparent only when the two pieces induced consistent differences in arousal and mood. In another study, 5-year-old children drew for longer periods of time after hearing familiar children’s songs than after hearing Mozart or Albinoni, and their drawings were judged by adults to be more creative (a facet of cognition), energetic, and technically proficient.4 This shows that the type of music that can cause arousal, and thus positively impact cognition, differs from one individual to another.

Costa-Giomi5 evaluated the effects of piano instruction on fourth-grade children attending public schools. Children in the experimental group received individual piano lessons weekly for 3 years and received a free acoustic piano. Children in the control group did not receive any formal instruction. Both groups had never participated in formal music instruction. A significant increase in self-esteem was apparent only in children who completed the 3 years of piano instruction.

Music is considered to be a universal language, and individuals with hearing loss following cochlear implantation can experience some of the benefits of music—such as relaxation, arousal, and change in mood—while listening to their preferred style of music. However, a great variability is expected in this effect related to age of implantation, motivation, sociocultural factors, the appropriate matching of processing strategies for each individual, and use of latest CI software.

Music Perception with CIs

Improved spectral resolution through current steering (reviewed in Part 1 of this article and illustrated in Figure 1) is expected to augment music perception in many listeners.6 Individual accounts have demonstrated some success of the current steering technique in enhancing music perception.7

Figure 1. A simplified illustration of “current steering” to create more channels within a cochlear implant. The site of stimulation is adjusted by manipulating the proportion of current delivered to each electrode in the electrode pair. The currents delivered to the electrode pair interact in the cochlea and create an intermediate “virtual channel.”

However, research with previous technology has also demonstrated benefits from CIs. Even though CIs cannot offer the rich spectral details provided by a normal ear, several anecdotal reports illustrate the esthetic gain adults with CIs receive from listening to music.8

Adults with CIs vary in their performance on musical listening tasks, and the performance is dependent on the particular selected task. For example, in one study,9 69% of the CI users were able to correctly identify timbre, 48% performed well on a pitch identification task, while 69% were able to discriminate pitch. A total of 41% of the subjects performed with 100% accuracy on a rhythm identification task, and 59% of the CI users correctly responded to all of the subtests on the rhythm discrimination task. Most studies suggest that, in terms of typical music listening, implant recipients can perceive much of the basic beat and simple rhythm patterns when the patterns are presented at moderate tempi.

As mentioned previously, individuals with CIs cannot be expected to have the same perception that normal-hearing listeners have while listening to music.10,11 However, up to half of the post-lingually deaf adults still enjoy music post-implantation.12 About two-thirds of the adults with CIs are optimistic because music appears to become more pleasant over time or because they feel that some music is better than no music at all. A few even consider music to be more pleasant through the CI than their memory of it prior to their hearing loss.13 Nonetheless, some CI users, who have previously experienced music through normal hearing and have a vivid memory of it, may find listening to the music through the CI less acceptable, less rich.

The case is different for individuals with congenital hearing loss who have not experienced music processed by a normal ear. Young congenitally or prelingually deaf implant users tend to enjoy music—some even report being avid fans of specific artists.11 They report enjoying it even when they are unable to recognize it.14

Parental reports similarly indicate that most children derive considerable pleasure from listening to music through their CIs,14 and as many as 78% of the parents observe greater interest in music in their child post-implant. Only 5% report apparent dislike of music following implantation.15 Based on parental reports, Mitani et al16 concluded that, in general, child implant users might enjoy music more than adult implant users.

The reason for music enjoyment by children may be that children probably focus on timing cues, which allow them to synchronize their dancing, tapping, and clapping to the beat of the music. Thus, it is not surprising that children with CIs engage in a variety of musical activities, including listening, dancing, and instrument lessons.11,14,15 Among elementary school-age children, 73% of the children who use CIs are enrolled in music instruction.15

Music Appreciation Through Hearing Aids vs Cochlear Implants

Due to the direct stimulation of auditory nerve fibers, music appreciation can be expected to be better with CIs than with hearing aids in individuals with severe-to-profound hearing loss who have very few surviving inner hair cells. Some adults with CIs report that their hearing aids did little more than transmit basic rhythmic pulses and that CIs offer more information about pitch and timbre than that offered by hearing aids.13

Looi et al17 compared the postimplant and aided preimplant ratings of musical quality of 9 individuals who were on the waiting list to receive implants. The ratings after CIs were significantly better than those obtained using hearing aids before implantation. Some of these individuals commented that with hearing aids they could hear only the beat of bass sounds, but with implants they could hear more of the higher-pitched melody instruments. Other individuals reported that with CIs they got a “broader picture” of the musical sounds with finer details.

Auditory Training and Music Perception

Effect of informal listening practice. Post-implant listening practice is correlated with improved music identification, perception, and appraisal.13,14 Regular deliberate listening to music improves identification accuracy; children who initiate music listening activities at home perform better.14 Longer listening hours per week are significantly associated with greater music enjoyment,12,13 suggesting the positive impact of informal auditory training.

Effect of incidental listening practice. Musical exposure often occurs incidentally, due to the presence of music on television shows, in movies, and in other public spaces. This type of incidental music exposure allows us to recognize the tracks or background music from movies, television programs, or commercials.

To examine the impact of incidental music exposure, Nakata et al14 evaluated the ability of congenitally deaf children (ages 4 to 9 years) with CIs to recognize the theme songs from popular TV programs that they watched regularly. All the children had worn CIs for at least 1 year. The children were able to identify excerpts from the original recordings. Vongpaisal et al11 also studied implanted children who were all congenitally or prelingually deaf. The children could identify popular songs in a closed-set task based on the excerpts from the original vocal and instrumental recordings. Similarly, Mitani et al16 examined the ability of children with CIs to recognize music from incidental exposure. The children identified the musical excerpts from the original vocal and instrumental versions at better than chance levels from a closed response set. These studies suggest the constructive impact of incidental exposure on music perception.

Effect of formal auditory training. Preliminary results suggest that formal training in the identification of melodic contour can significantly improve the identification of melodic contour, and this can also lead to improvement in the recognition of familiar melodies.18 Given the ability of the auditory system to change following repetitive stimulation (neuroplasticity), such findings are to be expected.

Significance of Processing Strategy and Fine-tuning

Different individuals benefit from different signal processing strategies for speech perception. The same is likely to be true for music perception. Thus, effort should be made in providing individuals with access to the processing strategy that leads to the enjoyment of their preferred music style. In some cases when the CI users have complaints, such as the music sounds too tinny or too hollow, fine-tuning of the CI in terms of the amount of current delivered to different electrodes may improve the perception of music.

Significance of Environmental Factors

Studies have shown that some factors can enhance music listening. These include a quiet listening background, use of direct audio input from the sound equipment, music played at moderate or soft volume, and visual cues that aid in interpreting the sound (eg, closed captions, music notes). Presence of background noise, poor quality sound equipment, and loud music (which tends to distort the sound) serve as deterrents to the music enjoyment.15 In addition to the above factors, a reverberant environment can be expected to reduce the music enjoyment without direct audio input or use of headphones.

Both background noise and reverberation should be minimized to the best possible extent in classrooms that provide music instruction to individuals with CIs. In addition, as many visual cues as possible should be made available for enhanced interpretation and enjoyment of the music.

Importance of ALDs

Music listening generally occurs through television, computers, or any variety of audio sources, including CD/DVD players, iPods, other MP3 players, etc. A handy way to achieve this with ear-level cochlear implants is to simply place the headphones from these devices over the microphone of the device.

However, for the best quality, all cochlear implants can be connected directly to CD players, television, or other sources through the use of standard patch cords. Patch cords are wires with a plug at each end that can connect the CI processor to the listening device. For optimal sound quality, the correct plug should be used, and this information is available from the manufacturers. In some cases, an adapter may be necessary.

Some direct connections cause deactivation of the microphone in the speech processor, which is desirable for elimination of all background interference. If the CI user wants to have the ability to monitor signals in the environments while listening to the audio source, this can be achieved through adjusting the settings or adding another microphone.

Besides direct audio input, some individuals may prefer wireless connections. For example, the transmitter of an FM device can be placed near the TV or home-theater speakers. The FM receiver can be placed near the listener. Some ear-hook options in CIs are capable of making wireless connections to some of the FM receivers without compromising regular power consumption.

A few CI users or their families may be reluctant at first to add another piece of equipment to the CI technology, which they may already perceive as being complicated, especially in the initial stages. The best way to present any assistive listening device is to demonstrate it rather than to describe it. The demonstration should allow the CI user to listen to sounds with better signal to noise ratio and to experience the ease of use.

The American with Disabilities Act (ADA) stipulates that ALDs be available in public places, such as movie and live performance theaters. Thus, CI users who are trained to be familiar and comfortable in the use of assistive listening technology can enjoy the music during live performances and movies. Similarly, ALDs should also be available for classroom use.

Significance of Cultural Values

The cultural values of each individual may play a role in music enjoyment. Many children are eager to fit into the larger world, assimilate with a variety of cultures, and have peer acceptance. They may even associate involvement with musical activities with peer acceptance. However, some individuals may take the position that deaf kids don’t need music; these individuals may dislike music. On the other hand, a few individuals may use the CI only for listening to music.15

Music Perception and Quality of Life

Hinderink et al20 found significant improvements in listening to music following implantation and suggested that being able to enjoy music can contribute significantly to a subject’s quality of life. Lassaletta et al12 found that about half of the post-lingually deaf adults enjoy music post-implantation, and such music enjoyment leads to better postoperative quality of life.

Critical Points

It is important to note that providing the option of CIs is only the first step. The patients and family members need to be made aware of all potential limitations and risks associated with CIs. It is also essential to make patients and families feel comfortable in accepting or rejecting the CI choice regardless of their selected mode of communication.

A total commitment from the family for caring and maintaining the device, and using it on a regular basis, is necessary for optimizing both the technology and neuroplasticity. The use of the CI should be slowly increased first in quiet environments and then in all environments. Most successful CI users utilize their implant for more than 12 hours a day.20 The ultimate success of the device for all CI users relies heavily on proper prefitting counseling, realistic expectations, and continuous support and follow-up during the postfitting period.

Although informal practice in listening to music can result in some music appreciation, formal auditory training may be necessary for full benefit, which requires a time commitment. Furthermore, older patients and families of younger children need to understand that years of experience in listening to the auditory enrichment provided by the CIs may be necessary before maximum benefit is apparent. In addition, adults with acquired hearing loss need to remember not to necessarily expect the same kind of “normal” perception from implants that they had prior to losing their hearing.

Summary

Music can reduce stress or induce relaxation. It can also improve self-esteem and some aspects of cognition, including math skills. For many individuals with severe-to-profound hearing loss, access to music is better through CIs compared to hearing aids. Although CIs cannot provide the same music perception as that provided by ears with normal hearing, several CI users enjoy listening to music. This is especially true for individuals with congenital hearing loss who have not previously experienced listening to music through normal ears.

Music enjoyment can be enhanced in a quiet background using moderate-to-soft music and visual cues. When possible, background sounds can also be eliminated through direct audio input. Research suggests that music enjoyment by CI users can lead to better postoperative quality of life.

References

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Correspondence can be addressed to [email protected] or to Vishakha Rawool, PhD, at .