Plasticity and tinnitus
Please note that I am neither a physician nor a neuroscientist. I’m just a guy with enough skills to locate scientific papers, understand them and draw my own conclusions.
Does Plasticity alleviate tinnitus?
I designed Plasticity in the hopes that it would help my (pure-tone) tinnitus (see “Did you try it on yourself?” below). Although the app is based on reasonable scientific hypotheses, so far there is no conclusive evidence that it is effective in reducing tinnitus. Trials using similar methods have yielded mixed results, with less than 50% of patients reporting modest subjective reductions in pure-tone tinnitus. See below for scientific details.
Note that whatever scientific justification Plasticity has, it applies only to pure-tone and narrowband tinnitus. If your tinnitus is of the noise variety, there is no reason why Plasticity would help you and might even be harmful (one user reported a worsening of his tinnitus after a Plasticity session, which may or may not be a coincidence).
If you would like to give it a try, you should understand that you are taking part in an experiment and doing so at your own risk. Nobody knows whether your condition will improve at all, and — who knows — it might even get worse! I am putting this application out there because I think everyone should be able to give it a try if they want to. Plasticity costs nothing and does not require you to undergo a surgical procedure or put drugs in your body. All you need to do is play a pretty fun game for 10-30 minutes every day. Given the low cost, if one in five people get some tinnitus relief after training with Plasticity, I will consider it a huge success.
Whether Plasticity helps you or not, don’t forget to post a comment here and tell me how it went. Seriously, I’m waiting for people’s feedback.
How is it supposed to work?
As you get better at recognizing differences between sounds, your auditory cortex gets “re-wired”, changing your perception of tinnitus.
Why would that work?
Source: Eggermont & Roberts,
“The neuroscience of tinnitus”
Tonotopic map for an example patient with tinnitus at 6000 Hz. Source: Mühlnickel et al.,
“Reorganization of auditory cortex in tinnitus”
Each of your brain’s hemispheres contains an area called the
A 1998 study by Werner Mühlnickel et al. showed that the tonotopic maps in many tinnitus patients are distorted: the neurons that respond to the tinnitus frequency are located in a different place than neurons for that frequency in healthy patients. If tinnitus is caused or at least accompanied by changes in tonotopic maps, then it might be possible to alleviate it by reversing these changes.
One of the ways in which the tonotopic map can be reorganized is simple training. In a 1993 study by Recanzone et al., monkeys were trained to recognize small differences in the frequency of tones. After the training, the monkeys not only got much better at detecting frequency differences — their tonotopic maps also had more neurons corresponding to the trained frequencies. This effect was not observed in monkeys that simply listened to the same frequencies without trying to discriminate between them.
How do I use Plasticity?
Whatever strategy produces progress should work fine. If you are able to reach higher and higher levels, that means your brain is adapting to the task, which is the result we’re aiming for. Nevertheless, here are some “speculative suggestions”:
- I would suggest training over at least 30 days for at least 2 rounds a day. Recanzone’s monkeys were trained on 400–750 tone pairs per day for over 60 days, though progress after the first 30 days was minimal. Beyond the first week or so, I don’t think it is necessary to train every day — every other day should be enough to make progress. Breaks may help you avoid getting bored and “dropping out”. It’s better to train every few days over a longer period than to train every day for a week and then give it up!
- Don’t do too many sessions in one day — it can result in overtraining and boredom. Often, you will find that you get the best scores in your first or second session of the day, when your mind is still fresh.
- Stay motivated. If you really want to get to the next level, you will learn faster. Perhaps you can compete with a friend?
- There are three ways to improve your results: (1) training when you’re well-rested, (2) caffeine, and (3) closing your eyes (this sharpens your hearing).
- You may find that you get better scores on speakers than on headphones. In my experiments, even laptop speakers were better than $200 headphones plugged into a good amplifier. This might be (this is pure conjecture on my part) because speakers allow the sound to resonate with objects in your environment, which gives your brain more data to work with.
- Volume probably doesn’t matter. In the Recanzone study, sound intensity (within the range of 25–60 dB SPL) had practically no effect on performance. Whatever volume gives you best perfomance should be fine.
What settings should I use?
If you hear your tinnitus in the right ear, you should probably choose the right channel. That means all the sounds will be coming from the right speaker or the right headphone. If your tinnitus is in the left ear, you should probably choose the left channel.
If you know the approximate frequency of your tinnitus, you can tell Plasticity to focus on sounds from that part of the spectrum. Just click the appropriate button and type in the frequency in the text box. The trained range will be 2 octaves wide and will usually be centered on the frequency you specified (unless your tinnitus frequency is close to the maximum supported frequency, which is 10,500 Hz). Using this option could theoretically speed up your tinnitus relief, as you no longer spend time training frequencies far from your tinnitus frequency (which should have little effect on your tinnitus).
If you would like to estimate your tinnitus frequency, try generating various frequencies using my online tone generator and check which one matches your tinnitus most closely. Note: Once you find a frequency that matches, also try sounds that are one octave lower (frequency divided by 2) and one octave higher (frequency multiplied by 2). Sounds that are one octave apart can sound very similar, so it’s easy to confuse them.
Did you try it on yourself?
Yep. I wrote Plasticity in April 2011 and started using it for about 20 minutes a day. My hope was that it would cure me completely. It didn’t. I thought I noticed some improvement, but that could have easily been simple placebo effect. After a month of using Plasticity, I went on a short foreign trip. During that trip, I noticed that I was able to fall asleep without masking noise for the first time since I got tinnitus. When I got back home, I decided to stop using masking at home as well. I also stopped using Plasticity. In the following months, my tinnitus gradually became a non-issue for me. I’ve gone weeks without noticing it. When I do notice it, it barely causes any reaction in me. I just go back to whatever I was doing and that’s that.
So if I wanted to sell you on the idea of using Plasticity, I could tell you that after a month of Plasticity, it became possible for me to fall asleep without masking. That would be true but misleading. The fact is, my condition had been improving prior to my experiment with Plasticity and it is possible that the improvement that came after my Plasticity training was a simple continuation of that trend. I have no way of knowing whether Plasticity contributed to my recovery. I’d say I’m about 50% sure that it did. It certainly made my brain better at recognizing pitch differences and by doing so, it might have altered the way I perceive the tone of my tinnitus.Has this approach ever been tested in a scientific setting?
Yes. The general picture is that a few studies have shown some positive effects of tone discrimination training, but the results could have easily been due to placebo effect, as none of the studies were properly controlled for placebo effects and all of them relied on subjective tinnitus measures, such as asking the patient: do you feel your tinnitus has improved? Of course, it is also possible that the experiments actually worked, either by making the tinnitus quieter by inducing changes in the auditory cortex (which was the intended result) or making it less annoying through some as yet unknown mechanism.
Here is a good review of the efficacy of auditory training for tinnitus (note that it covers other training schemes in addition to the one used in Plasticity).
Here are my summaries of three studies that closely match the way Plasticity works:
- Herta Flor et al. (2004): 12 patients with tonal tinnitus underwent tone discrimination training for 2 hours a day for 4 weeks. Subjects used a computer program in which they were repeatedly asked to decide whether the two sounds they just heard had the same frequency. Task difficulty was increased as learning progressed. After 4 weeks, a small reduction in tinnitus severity (as measured by a questionnaire) was achieved in patients who completeted 27 or more training sessions, but not in patients who completed 23 or fewer sessions. There was no difference in effectiveness between patients who trained on frequencies close to their tinnitus frequency and those who trained on frequences distant from their tinnitus frequency. Note that 2 patients experienced an increase in tinnitus during (because of?) the study. (PubMed, full text)
- Carlos Herraiz et al. (2007): 22 tonal tinnitus patients underwent frequency discrimination training for 10 minutes twice a day for one month. Each patient trained only one frequency: 4, 6 and 8 kHz. In each pair, one of the tones could be 0.5 kHz higher or lower. Tones differed by “time of presentation” (duration?) as well as frequency. As in the Flor study, subjects were asked to decide whether the tones are the same or different. Overall, 45.5% of subjects reported an improvement in subjective tinnitus severity, as measured by the question: is your tinnitus better, same or worse since we started the treatment? No subjects reported a worsening of tinnitus. Tinnitus severity according to the Tinnitus Handicap Inventory (THI) also decreased by a small, but statistically significant amount. Tinnitus intensity measured on a visual analogue scale decreased by an insignificant amount. In addition, the study examined two groups of subjects: one trained frequencies similar to their tinnitus frequency (since the trained frequencies were 4, 6 or 8 kHz, they could have been only very roughly matched to the subjects’ tinnitus), the other trained frequencies more distant from the tinnitus frequency (but still less than an octave away). The results were better for the more distant frequencies, but the difference was not statistically significant, so it could have been due to chance.
- Carlos Herraiz et al. (2009): This is a very similar but larger study conducted by the same group. It comprised 41 patients in treatment groups plus 26 patients in a control group (no placebo). Each patient trained only one frequency: 4, 6 and 8 kHz. In each training pair, one of the tones could be 0.1–0.5 kHz higher. Training duration was 20 minutes per day for 30 days. Of all treated subjects, 42.2% reported a decrease in subjective tinnitus severity as measured by the question: is your tinnitus better, same or worse since we started the treatment? The paper does not mention any subjects who felt their tinnitus got worse in the course of the treatment. There was also a small, but statistically significant drop in THI scores. Tinnitus intensity measured on a visual analogue scale decreased by an insignificant amount. In addition, the study examined two groups of subjects: one trained frequencies similar to their tinnitus frequency (since the trained frequencies were 4, 6 or 8 kHz, they could have been only very roughly matched to the subjects’ tinnitus), the other trained frequencies more distant from the tinnitus frequency (but still less than an octave away). The results were better for the more distant frequencies, but the difference was (just barely) statistically significant only when measured with THI.
Where can I find further information on tinnitus?
I’ve written a blog post titled “Tinnitus tips” in which I present some techniques that helped me get over my tinnitus. The post contains links to high-quality resources on tinnitus.