The purpose of this study was to evaluate the therapeutic effect of three different types of sounds on tinnitus patients undergoing tinnitus retraining therapy (TRT).
This is a single-institution retrospective study, performed in one tertiary otological referral center. Thirty-eight adults with subjective idiopathic tinnitus who were followed for at least 9 weeks were enrolled. Sound therapy was delivered in 3 different ways: narrowband noise TRT (nTRT); mixed band noise TRT (mTRT); broadband noise TRT (bTRT). Treatment response was measured through validated psychometric questionnaires: Tinnitus Handicap Inventory (THI), visual analog scale (VAS) on annoyance, and numerical description of hours of tinnitus perception (awareness hours).
A total of 38 patients were followed for at least 9 weeks. In nTRT group, all outcome measures including THI, VAS, and the awareness hours, decreased over 9 weeks with no statistical significance. In mTRT group, all outcome measures except for awareness hours significantly improved 9 weeks after the beginning of the treatment. In bTRT group, all outcome measures decreased significantly in 9 weeks. When therapeutic success is defined as improvement in THI 7 or more, bTRT group (77.8%) showed a higher success rate than other groups for 38 patients with the minimum follow-up of 9 weeks.
All three sounds can provide relief in patients with annoying tinnitus after TRT. However, there is difference in the therapeutic effect according to sound types. Broadband sound seems to be better than narrowband sound or mixed sound in relieving the patients from tinnitus. Therefore, sound therapy with broadband noise may be more appropriate during TRT, but further evidence is needed for precise conclusion.
Tinnitus is generally defined as a perception of sound in the absence of an external acoustic stimulus. Tinnitus affects approximately 50 million Americans and more than 600 million individuals worldwide [
Tinnitus negatively affects overall quality of life including daily activity and social activity. The etiology is not fully understood and thus no treatment method can completely cure tinnitus. There is no single treatment for tinnitus: many modalities including life style modifications, medications, masking, transcranial magnetic stimulation and retraining have turned out to be imperfect [
In this study, we included 38 patients with subjective idiopathic tinnitus: 24 men and 14 women, who were followed for at least 9 weeks between March 2008 and December 2010. Patients were classified into 3 groups on the basis of the type of sound introduced: narrow band noise TRT (nTRT), mTRT, broadband noise TRT (bTRT). All patients underwent a standardized intake assessment [
Patients were allocated to each sound type according to their visiting period, firstly nTRT was adopted, later mTRT, lastly bTRT was used for the treatment of tinnitus. This is not a prospective randomized clinical trial, however, the staged implementation of three different sounds supported such a comparative evaluation. Although the three programs were separated in time, they were the same in terms of intended protocols, physician in charge, counseling methods, sound therapy device, and location of the program. The only intended difference was the type of sound used for TRT sound therapy. Patients were assigned to nTRT, mTRT or bTRT: 8 in nTRT (5 males, 3 females; mean age, 38.9±9.8 years); 12 in mTRT (8 males, 4 females; mean age, 47.78±13.5 years); 18 in bTRT (11 males, 7 females; mean age, 55.7±15.4 years), respectively.
Patients' data were collected at 2 points: 1-5 week and 9-13 week. No differences were found in the mean number of weeks at each follow-up point among three groups. For 1-5 week, mean follow-up period was 2.86±1.22 weeks for nTRT group, 2.82±1.08 weeks for mTRT group, and 2.43±1.28 weeks for bTRT group (
Sound therapy was conducted with a MP3 player (Sandisk, Milpitas, CA, USA; CE007K, LETO GMS, Seoul, Korea). In the nTRT group, narrowband noise that matched to the patient's tinnitus pitch was provided to the patient. In mTRT group, initially narrowband noise was used to mask the tinnitus for short term (≤1 months), then for the next 2 months of treatment, the composition of sound was changed from the dominance of narrowband noise to the dominance of broadband noise (white noise). In bTRT group, white noise was used from the beginning. The patients were instructed to set the volume of noise generator at the mixing point [
During sound therapy, patients attended counseling appointments with the otolaryngologists at 1, 2, and 3 months and completed questionnaires. At the first visit, patients received a 15 minute counseling about causes of tinnitus, why tinnitus becomes a problem, explanation of habituation as a goal and were reassured. Every month after the first visit, patients attended ongoing counseling for 5 minutes with the otolaryngologists to check subjective annoyance, compliance to treatment and repeated explanation of habituation as a goal.
Three outcome instruments (Korean version THI, VAS on annoyance, numerical description of tinnitus perception) were used. The THI has 25 items and a range of 0-100 (α=0.93;
The Wilcoxon signed rank test was calculated for a comparison of THI, VAS, and awareness hours over time within each group. The Kruskal-Wallis test and linear by linear association analysis were used to compare the THI, VAS, awareness hours, and success rate between groups. Null hypotheses of no difference were rejected if
In the nTRT group, all outcome measures including THI, VAS and the awareness hours decreased after 9-13 weeks (
In mTRT group, THI and VAS significantly decreased for the duration of 9-13 weeks (
In bTRT group, all outcome measures improved significantly for 9-13 weeks (
A gradual improvement over time in THI score was found in all groups (
The successful treatment rate was 77.8% for bTRT, 58.3% for mTRT, and 37.5% for the nTRT group. Success rate was compared between groups with linear by linear association analysis and sound therapy with broadband noise showed better results than that with narrowband noise and mixed noise (
It is generally accepted that sound therapy with broadband noise is suitable for TRT. But this practice is based on theoretical assumptions that broadband noise may activate the greatest number of auditory nerve fibers facilitating habituation [
TRT is based on the neurophysiological model of tinnitus introduced by Jastreboff [
According to the randomized controlled trial reported by Henry et al. [
This study has a limitation stemming from a number of variables which might influence the outcomes such as difference in mean age between groups. We tried to control this factor. But due to the retrospective design of the study it was basically not manageable. Also, the number of subjects is not enough to draw a firm conclusion. It might have shown a robust difference if the number of subjects had been sufficient. The staged implementation of three different programs may also be source of bias. Although we tried our best to keep the program fixed and only allowing sound therapy to change, clinical setting elements may have changed during the long period of patient recruitment. It would have been ideal if we had carried out a randomized prospective trial, but unfortunately this was not the case. Potential confounding factors are being controlled for in a continuation study which will be prospective, randomized controlled study. Although the aforementioned factors are important shortcomings of this study, we hope these factors did not undermine the main results of this study.
In conclusion, it is generally accepted that sound therapy with broadband noise is suitable for TRT. But this point has not been backed up with experimental data before. Through this study we have found that narrowband noise as well as broadband noise may relieve the patient of distracting tinnitus. Although not conclusive, broadband noise seems to be more efficient in improving the patient's distress due to tinnitus. bTRT is not disadvantageous when compared to nTRT and mTRT from the beginning of treatment within 5 weeks and bTRT is the only modality to improve all three of outcome measures (THI, VAS, and awareness hours) after 9-13 weeks. The results might support the use of broadband noise from the beginning of sound therapy during TRT. Further study with more subjects and longer follow-up period is necessary to draw a more precise conclusion.
No potential conflict of interest relevant to this article was reported.
Mean changes from baseline in questionnaire scores for patients who were treated with narrowband noise tinnitus retraining therapy (nTRT) and followed for more than 9 weeks. All three outcome measures including Tinnitus Handicap Inventory (THI) (A), visual analog scale (VAS) (B), and the awareness hours (C) decreased after 9-13 weeks. THI decreased from 48.25±25.56 to 42.0±29.55, VAS decreased from 6.50±1.60 to 5.63±1.69, and the awareness hours decreased from 16.75±8.41 to 15.13±10.82, respectively.
Mean changes from baseline in questionnaire scores for patients who were treated with mixed noise tinnitus retraining therapy (mTRT) and followed for more than 9 weeks. In mTRT group, Tinnitus Handicap Inventory (THI) (A) and visual analog scale (VAS) (B) significantly decreased for the duration of 9-13 weeks. THI decreased from 42.5±22.27 to 29.0±26.55, VAS decreased from 6.17±1.34 to 4.33±2.06, respectively. Awareness hours (C) decreased from 16.67±9.25 to 9.83±10.94 but it did not reach statistical significance. *
Mean changes from baseline in questionnaire scores for patients who were treated with broadband noise tinnitus retraining therapy (bTRT) and followed for more than 9 weeks. In bTRT group, all outcome measures showed a statistically significant improvement for 9-13 weeks. Tinnitus Handicap Inventory (THI) (A), visual analog scale (VAS) (B), and the awareness hours (C) decreased significantly from 54.22±22.41 to 35.11±22.44, from 6.50±1.47 to 5.11±2.14, and from 18.17±8.63 to 13.83±10.00, respectively. *
Improvement in Tinnitus Handicap Inventory (THI), visual analog scale (VAS), and awareness hours for patients who were followed for more than 9 weeks. A gradual improvement over time in THI score was found in all groups. When the change in THI score was compared between groups, broadband noise tinnitus retraining therapy (bTRT) group seemed to show the best results, bTRT showed the poor results, and the effect of mixed noise tinnitus retraining therapy (mTRT) was intermediate (A). VAS also showed a general improvement over time in all three groups. When compared between groups, VAS outcome was comparable between mTRT group and bTRT group, but it was relatively poor in the narrowband noise tinnitus retraining therapy (nTRT) group (B). In terms of awareness hours, a general improvement was shown for the duration of 9-13 weeks. When the change in Awareness Hours was compared between groups, mTRT group and bTRT group showed the comparable improvement, and nTRT group showed the poor result (C). However, all this result did not reach statistical significance.
Comparison of successful treatment rate between groups. The successful treatment rate was 77.8%, 58.3%, and 37.5% for broadband noise tinnitus retraining therapy (bTRT), mixed noise tinnitus retraining therapy (mTRT), and narrowband noise tinnitus retraining therapy (nTRT) group respectively. Sound therapy with broadband noise tended to show better results than that with narrow band noise and mixed noise. THI, Tinnitus Handicap Inventory. *