Clinical Information
Abstract
Tinnitus affects 10 – 15% of the population and can be a debilitating problem for those who suffer from it on a full-time basis. This study examines the daily use of low frequency sound therapy for the alleviation of tinnitus severity. This was done using a four-week long randomised controlled trial, an active treatment and control group, and recognized tinnitus self-assessment questionnaires. The Tinnitus Handicap Inventory (THI) was filled in at the beginning and end of the trial, and once a week while the Tinnitus Functional Index (TFI) was completed at the start and end of the four-week trial. Statistical tests such as Analysis of Variance (ANOVA), regressions, and confidence intervals were then used to assess the significance of the differences in the active treatment and control groups. The results of the TFI demonstrated a significant reduction in tinnitus severity and the THI indicated a significant result at the end point measurement (both at p < 0.05). In conclusion there is a proven significant downward trend in the tinnitus severity of those who used low frequency sound therapy daily for a four-week period.
Study
This study examined the therapeutic benefit of SoundRelief low frequency sound therapy in the treatment of tinnitus. The sound therapy was delivered via an MP3 file and listened to using headphones. Sound therapy aims to modify the neurological signals associated with tinnitus. Depending on the type of sound therapy this may take place by way of residual inhibition, or post-masking suppression of tinnitus, if inside the tinnitus spectrum or perhaps by lateral inhibition if out with the tinnitus spectrum. The sound therapy tested in this study is considered to be passive, in terms of listening experience, and is outside the typical tinnitus spectrum.
The study was a randomised controlled trial (RCT). Around 200 participants were required to observe a statistically meaningful result. 301 candidates started the trial with 275 completing it. Candidates were randomly assigned into two groups:
- Active treatment group filled in questionnaires periodically and used sound therapy for five minutes every day. Control group only did the questionnaires.
- Two scientifically recognised questionnaires were used – Tinnitus Handicap Inventory (THI) and Tinnitus Functional Index (TFI).
The demographics of those who took part in and completed the trial were examined for their similarity to the general tinnitus population. There were no unexpected variances in the demographics of those who participated in the trial.
60% of participants were male, and 94% of candidates had permanent tinnitus for less than 15 years. Most experienced some degree of hearing loss (characterised as mild, moderate, and severe) where 16% of participants had no hearing loss. The majority (87%) of candidates were between 45 and 74 years old. People reported a broad range of sources for their tinnitus, as shown in figure 1.
| Cause of Tinnitus | % of Trial Population |
|---|---|
| Noise Related | 32 |
| Unknown | 30 |
| Head Surgery / Trauma | 12 |
| Stress | 5 |
| Infections | 7 |
| Hearing Loss | 6 |
| Medication | 5 |
| Other | 3 |
Figure 1.
Statistical significance means that an observed effect, or change, is as a result of more than just chance. Effect size is the impact of the result on a population as a whole. Different tests can be used to compare the changes in the groups and whether that change is statistically significant.
Four tests were used in this study – Analysis of Variance (ANOVA), regressions, cluster analysis, and confidence intervals. Several analyses all report a statistically significant result for the Impact of treatment on TFI and THI scores, when the scores were considered both separately and collectively. Focusing on the TFI, the whole active group had their score reduced by 13% in 30 days, as shown in figure 2.
However no tinnitus therapy is expected to work for everyone, so breaking that down to those who received a benefit (two-thirds of candidates) a 25% reduction was observed. A clinically significant result, minimum 14 point reduction in TFI score, was demonstrated in 25% of trial candidates. These results were observed as having a medium effect size.
Attrition (drop-outs) were not found to have a significant effect on the results.
Figure 2.
This study set out to test the hypothesis that four weeks of using low frequency sound therapy for five minutes a day would reduce tinnitus severity in permanent tinnitus sufferers. This question was approached in a scientifically robust way, which is not always the case in tinnitus research.
A randomised controlled trial was designed and run on a sample of 301 people, with 275 completing the trial. This was larger than the sample size required for detecting a medium effect size at power of over 90%. Data were collected using established questionnaires for the assessment of tinnitus severity and the trial took place online with participants from all over the world.
Multiple methods of statistical analysis were carried out on the data – regression, confidence intervals, cluster analysis, and ANOVA – in order to make the most conclusive statement possible about the results. In analysing the tinnitus severity of both the active and control groups it can be concluded that a statistically significant result was observed after 30 days, when SoundRelief treatment was used for five minutes a day. Several points of this study merit further exploration: the nature of the scores beyond 30 days and segmentation by cause of tinnitus.
In conclusion, there is reliable evidence that using low frequency sound therapy for five minutes a day for at least a month will reduce tinnitus severity in permanent tinnitus sufferers.