Feb 2021 The Hearing Journal
Cochlear implants (CIs) have been reported to help decrease tinnitus while aiding the user's hearing, but studies have shown that about 50 percent of CI users remain aware of their tinnitus and about 25 percent still experience troublesome tinnitus. “Interestingly, it is reported that a substantial amount of unilaterally implanted patients with bilateral hearing loss reported their tinnitus to be their primary concern after implantation,” noted Remo Arts, PhD, and Jan van Heteren, MD.
To address this issue, a recently published study by Remo, van Heteren, and colleagues suggests that sound therapy using common background sounds may relieve tinnitus in some CI users who still experience this problem.
The study was split into two phases: first, to determine the acceptability of six natural background sounds for therapy, and second, to determine the efficacy of sound therapy in relieving patient's daily experience of bothersome tinnitus.
In both phases, the study's sound therapy strategy used water-based background recordings—Shoreline, Beach Surf, Breaking Waves, Calming Waves, Ocean, and Water Creek—that were played directly from the sound processor of a patients’ CIs via an algorithm called Cochlear Active Relief from Tinnitus (CART).
Of the 32 participants in the first phase, 30 (93.8 %) found at least one background sound to be “acceptable at their preferred volume” and 19 (58.4 %) found all six background sounds acceptable.
Fourteen of these participants then completed phase 2. First, the study authors measured the participants’ tinnitus loudness, annoyance, and effect on daily life during a two-week baseline period without sound therapy. The participants then attended a brief tinnitus counselling session before undergoing a five-week intervention period using sound therapy in their daily lives.
The researchers measured a significant improvement in both tinnitus annoyance and loudness. They found sound therapy “effective in reducing tinnitus for seven out of 14 subjects who completed the take-home evaluation.” The study also showed that sound therapy was safe and easy to use, and did not adversely affect speech perception.
While optimistic with their research findings, study authors Arts and van Heteren pointed out that some participants experienced sound therapy differently. “From this study, we learned that background sounds played directly from the sounds processor of the cochlear implant are generally acceptable and have no detrimental effect on speech perception. There is, however, high variability between subjects in terms of the effectiveness and acceptability of background sounds,” said Arts and van Heteren.
For instance, the acceptability of each background sound and the preferred volume levels were “highly variable” among participants. Further, three of the study participants experienced increased tinnitus annoyance during the therapy period; of these three, two also experienced louder tinnitus.
The present study notes that “[s]ound therapy does not benefit all patients and it is not clear why some of them report that background noise makes their tinnitus worse, whereas others report that background noise makes their tinnitus better.”
Previous studies suggest that some factors may potentially increase the positive treatment effect of sound therapy. These include “a flat audiogram configuration (rather than a gently or steeply high-frequency sloping audiogram), younger age, and higher tinnitus handicap inventory scores.”
A particularly positive finding from the recent study was that “some CI users with tinnitus highly appreciated the sense of control they experienced with sound therapy,” even when tinnitus relief was not always clinically significant.
Citing previous literature, the study explained, “The possibility to use background sounds in specific situations potentially gives CI users with tinnitus a sense of control that helps them to get relief from tinnitus which may positively affect their quality of life.”
The authors are hopeful that the study's key findings can help future research and commercial applications for CI users with tinnitus. “This study investigated sound therapy in CI users and provided insight into sound selection, volume settings, and its use in different sound environments. The results are valuable for guidance in future trials or clinical use of any commercial application that can be used as an ‘add-on therapy’ for CI users with tinnitus, where the CI itself does not provide enough tinnitus reduction.”
Arts and van Heteren added that the CART algorithm applied in their study has the potential to be more useful to patients. “For those with ongoing, postoperative tinnitus, CART might improve usability beyond what is possible already today with e.g., a sound enrichment app and direct streaming.”