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Does listening to a 40 Hz tone “clean up“ the brain in Alzheimer’s patients?

In 2012, I made a Web-based tone generator with the goal of helping tinnitus patients determine the frequency of their tinnitus to better target therapy. Since then, I have heard from people using my generator to teach physics, practice violin, drive away carpenter bees, tune DIY speakers, analyze room acoustics, calibrate vintage synthesizers, cause mischief in class with frequencies the teacher can’t hear, and even open a portal to Sedona, AZ. Far be it from me to take away from all these worthwhile applications, but last week, I got a message from Dennis Tuffin (of Devon, England), describing a new use for my generator which may very well trump everything else:

For the past 7 weeks I have been using your tone-generator for a purpose I wouldn’t think you had envisaged but about which I am sure you will be interested.

I have been following up on some research which my daughters had done about the treatment of Alzheimers by using a 40Hz flickering light source or alternatively a 40Hz sound source. There is sparse info on the net about these experiments though there is a recent piece about it. [here Dennis is referring to this paywalled article]

So I have been trying the sound therapy on my wife who is in the advanced stages of Alzheimer’s and to my surprise after 8 days she started to show small signs of being more mentally alert than before. So I have continued to use your tone generator using a 40Hz sine wave for about an hour each day. (I’ve recently started to do it twice a day for slightly shorter sessions). I found it necessary to connect external speakers to my laptop in order to pick up such a low note and to run it at a level of between 46-54 decibels so that she hears it wherever she is in the room. (Dementia sufferers get very fidgety!). So now 7 weeks on the improvement in her awareness has continued to the point where she is starting to be able to put a few words together and to respond to questions neither of which she has been able to do for nearly a year. Her odd physical habits have not been changed so far but she is definitely walking better and not shuffling her feet as she used to. Surprisingly, she is also sleeping better and not suffering as much with the sleep apnoea problem that she’s always had.

Photo of laptop and a small speaker on a kitchen countertop

The setup used by Dennis. The black box on the left is the external speaker.

Of course I expect there to be a limit to this progress as in the 8 years since my wife was first diagnosed her brain will have shrunk considerably so I do not expect her memory to return but on the other hand my wife’s quality of life has been improved.

To date I have not gone public on this and only close family have known but by the end of another week when it will be 8 weeks since we started I think I would like to spread the word and hopefully prompt a few professionals to do more proper research.

The science so far

  • It has been known since at least the 1980s that cognitive activity triggers brainwaves (wave-like patterns of activation) at a frequency of 40 Hz in humans and other mammals.
  • In 1991, researchers from the NYU Medical Center discovered that Alzheimer’s patients have reduced 40 Hz brainwaves compared with healthy people. (paywalled paper)
  • In 2016, MIT’s Alzheimer’s group did experiments on transgenic mice with early Alzheimer’s disease and found that exposing them to a light flickering at a frequency of 40 Hz (40 times a second) for 1 hour a day for 7 days causes an almost 60% reduction in β-amyloid plaques, which are a molecular hallmark of Alzheimer’s. 20 Hz and 80 Hz tones did not have the same effect. An important qualification here is that the effect was limited to the visual cortex, which is not significantly affected in human Alzheimer’s patients. Here’s an accessibly written report in The Atlantic and here’s the original paper (published in Nature) if you’re strong in science-speak. MIT also made a video about the findings.
  • According to the New Scientist (paywalled article), the same MIT team achieved even better results by playing mice a 40 Hz sound. β-amyloid plaques shrank by about 50% in the auditory cortex and – crucially – in the hippocampus, perhaps because the two areas are close to each other. This is a very important discovery, because the hippocampus is the region of the brain which is involved in forming memories. It is the hippocampus that suffers the most damage in human Alzheimer’s patients. As of 1 Mar 2018, these results have not been published, but were presented at the Society for Neuroscience conference in Washington in November 2017.
  • In March 2016, scientists at the University of Toronto published the results of a small, placebo-controlled pilot study (paywalled paper), in which they exposed 20 Alzheimer’s patients to a 40 Hz sound. After six 30-minute sessions (done twice a week), the patients’ average score on the 30-point SLUMS scale improved by 4 points, while the placebo group did not improve. It should be noted that the “dosage” of the treatment was rather low, which may explain the modest results.

Further reading/listening

Technical advice

If you want to try playing a 40 Hz tone to someone with Alzheimer’s, here’s some technical advice:

Getting a 40 Hz tone is easy – you can use my frequency generator. (Please note I do not take responsibility for the purity of the produced tone, as it is generated by your Web browser – though I think it should be fine. By the way, I am also not a doctor and I am not giving medical advice or offering any medical product here.)

You will need decent speakers. 40 Hz is a very deep bass tone – the kind of rumbling tone that you feel in your body as much as you hear it. Small speakers, such as laptop speakers or small computer speakers don’t go that low. If you try anyway, you will either hear nothing, or you will hear mostly – or only – distortion. What is distortion? It’s a higher-pitched, buzzing noise that speakers make when you push them too hard.

Photo of a bookshelf (monitor) speaker

A bookshelf speaker (photo: D. Cedler)

Bookshelf speakers will do 40 Hz, but their output at that frequency will be significantly reduced, so you will need to turn up the volume significantly, and they will produce easily audible distortion. Because the ear is more sensitive to high frequencies, the distortion may be subjectively louder than the fundamental 40 Hz tone, and may make the sound harder to tolerate, thus limiting the volume (and possibly the therapeutic effect).

The best solution is a high-quality subwoofer. It won’t be distortion-free, but you can expect the distortion to be 2–3 times quieter than with bookshelf speakers. This will give you as pure a tone as you can get. If you don’t care about playing music, you can get just a subwoofer (without any other speakers) and connect it to your computer or mobile device.

A neat trick to amplify the bass output of any speaker is to place it against as many walls as possible. For the maximum boost, put the speaker(s) on the floor, in a 3-way corner between two walls and the floor – that way, it will be adjacent to three surfaces.

How important is sound quality? It’s hard to say. Dennis seems to have had great results with cheap computer speakers. It is not known to what extent the therapeutic effect depends on volume or the presence of distortion. On the other hand, if you use small speakers, it won’t be obvious whether they’re actually playing 40 Hz or just distortion – so it’s worth getting something bigger just to be on the safe side.

Can you use headphones instead? It’s hard to say with certainty, as a 40 Hz tone played through your speakers will not just be heard with your ears – it will also be felt in your whole body. With headphones, the effect is strictly auditory. However, so far I haven’t seen any specific scientific reasons to suggest that this difference is important. If you decide to use headphones, make sure they can do 40 Hz. The earbuds that came with your smartphone are probably not the way to go here. HeadRoom has a database of frequency response graphs for high-quality headphones, so you can check how loud a given model is at 40 Hz. Want a specific recommendation? Get the Koss Porta Pros (Amazon.com, Amazon.co.uk). They’ll do the job, they’re the most comfortable headphones I’ve used, and – at $40 – they’re tremendous value.

Call for comments

If you or your loved one has Alzheimer’s disease and you have tried 40 Hz sound therapy, please share your experiences – whether positive or negative – in the comments section below.

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22 Comments so far ↓

  • James

    Just found this article – I am setup with a 10in powered SUB and 2 Control Monitors – 40hz can shake the whole house! I am glad to have found this article as I ma starting a journey too research sounds for myself and rediscover what we forget a long time back. Look forward to the next few years! James

  • Gregory

    I had a sub-woofer sitting around & hooked it up for my 97 y.o. Mom – who seems to us to be in the early stages of dementia. (She has an appt. this summer for testing.) I began Tx on 3/12/18 at 1 hr./day.
    After 1 week we were encouraged that none of us minded the rattling very much – my 94 y.o. Dad’s hearing ain’t the best anyway. And watching Mom’s card playing we imagined that progress could be happening.
    I am keeping an acct. of relatively objective measures; & by the 2nd week Mom’s behavior was improving convincingly. Disclaimer: none of this measures up to what one might consider scientific-level evidence — unless, maybe, you’re a Trump supporter…. All purely anecdotal; but we’re convinced.
    So now we’re at almost 3.5 weeks & Mom’s playing Rummy w/ my Dad & no longer needs help dealing, keeping track of where she is in the game, adding her own score. She made a comment during Red Sox game 2 days ago that evidenced that she’d remembered a home run charity benefit donation program that hadn’t been announced in quite some time. These are abilities she hadn’t demonstrated for many mos.
    So, we’re not quitting. I’ve no idea the volume, & of course these frequencies find resonating, standing-wave nooks & crannies all over the room. We keep it at a bit below uncomfortable for “The Wife” & I, and make sure that the Parental Units are in a loud corner – sleeping or awake, as the case may be.
    Thanks everyone for the actual scientific citations & tips. We’ve made the first of our donations today, Tomasz.

    • Tomasz P. Szynalski

      Hi Gregory, that’s awesome to hear! Thank you for writing in and for your donation.
      I’m looking forward to further reports from you, even if they’re less positive. It’s very important that we get as many reports as possible, as it will be a while until we get clinical trial results.

      PS. I had to look up “Tx”. Now I know it means “treatment” 🙂

    • Raymond

      How is your mom doing now?
      What type of subwoofer (as far as size is concerned) did you use?
      Was it an active subwoofer or a passive one?
      Where did you get the 40 hertz tone?
      I really appreciate in advace.
      My mom is much younger than your but she is suffering from this horrible disease.

  • Stockett

    I have been following these scientific development 40 Hz therapy for afew of years. My wife has Posterior Cortical Atrophy (PCA) which is also known a Visual Variant Alzheimer’s. Although they are not sure because of limited research, it is believed to be a rare form of Alzheimer’s that strikes earlier and most often affects the visual cortex area of the brain first affecting vision perception. Even though there is no evidence the 40 Hz therapy will work on this variant of the disease, I decided to try it.

    I first purchased LED lights that flickered at 40 Hz. Since they were placed across her room I didn’t notice any improvement.

    Several months later, I switched over to using 40 Hz sound from a frequency generator on a iPhone. I did this before the scientific community reported using the audio strategy because it seemed logical that any 40 Hz input into the brain would be beneficial via any of the senses. I didn’t use both together because I knew they wouldn’t be synchronized and figured that would not be good. I later found a device on the Internet that looks like a little mp3 player that played a 40 Hz sound and I purchased a couple of them for about $22 each. These are very convenient because I don’t have to worry about the frequency accidently being changed.

    She has been using the sound therapy for several months now, usually for 1-2 hours per day. Within about a week, we saw some subject improvements. The improvements aren’t major but it seems to me that her improvements have plateaued. Even that is positive if it is helping to prevent decline.

    Next I am going to try playing the 40 Hz through my stereo system which has a sub-woofer. I will keep it at a low level for most of the day as a background noise.

    We have to fight these dementia related diseases with every tool in our toolbox. From the time my wife was diagnosed with PCA we have researched and applied every safe, tested, double-blind tested (in most cases) strategy we could find (healthy foods, supplements, etc.). I am sure all of this has greatly slowed her progression as it has been 18 years since I first noticed symptoms in her and she it still working, though we don’t know how much longer.

    Thanks for the information you provided on this page. I will save it and share it with others.

    • Tomasz P. Szynalski

      Thanks for the report. Which device did you buy? Is there a Web page for it?

    • Jose

      I also tried the lights flickering at 40hz for mom. Instead of placing them around the room, I rigged up a Google cardboard 3-d viewer put the string lights in there. I tried this for myself for a few days (at 1hr per session) just to make sure it wouldn’t be blinding or uncomfortable and it is not, at least for me. In my own trials, unwittingly before knowing about this research, I also plugged in some headphones with the Binuaral app playing sound at 40hz. It’s free on the iTunes app store.

      Since coming upon this 40hz sound research (about 3 days ago on June 16, 2018) I’ve looked for other apps and found several that produce 40hz.

      **Where I would appreciate some help from audio engineers or those versed in audio maths, is in determining whether the bass frequency matters, because there is a difference in the sound from the “Binaural” app, the “Binaural Beatbox” app and the “Binaural Beats Generator +” app (the latter which allows you to control both the “Binaural Beat” and the “Base Frequency”) Any idea what the “Base Frequency” should be set at? I scanned the article in Nature but I couldn’t decipher that figure, or if it’s even present in their research.**

      I’m praying that this treatment will help restore health and memory to those who suffer from some form of dementia, as well as relief to their families and/or caretakers.

      Regards,
      Jose

      • Tomasz P. Szynalski

        In the Nature study, they didn’t use beat sounds – just normal 40 Hz sounds.

        • Jose Gonzalez

          I don’t know what the difference is between regular and beat sounds. If you do, could you please explain? Thanks!

          • Tomasz P. Szynalski

            It’s kind of hard to explain. A regular 40 Hz sound is when the air pressure changes 40 times a second. Your ears register that as a deep bass tone. A “beat sound” of 40 Hz is when you have a pure tone of whatever frequency (e.g. 1000 Hz) and then you vary the volume of that tone 40 times a second. That’s not perceived as “deep” — it just sounds like an unstable, warbling 1000 Hz tone.

    • Raymond heda

      Please tell us what device you used and the address of the web site you bought the device from.
      Thanks

  • Garth

    Hi
    I think the website/product Stockett referred to is https://www.gammalighttherapy.com/ I purchased their light and sound devices and am using them right now.

    My father had dementia and I’m wanting to use gamma frequencies as a preventative measure. Stockett commented that he wouldn’t use the light and the sound together as they wouldn’t be synchronized. Could anyone comment on this more – could the two if used together not be as effective?

    I’m also wondering about how audible the 40 hz should be. The device from the website produces a very audible sound that is going to take some getting used to. 40 hz though is at the edge of human hearing – what does it sound like though a subwoofer? I can’t hear it all through my laptop speakers or though headphones.

    Thanks for this discussion. I hope the research is moving along quickly. Finding a prevention for dementia would be life changing for so many.

    • Paul Mordetsky

      I purchased their tone generator, and it seems pretty tinny, tiny, and awful. I am wondering if it really is 40 hz , as it seems higher pitched. I am probably going to send it back

  • Garth

    Sorry to bother again – since posting I found this website
    https://www.youtube.com/watch?v=uYEiquXgMKU
    that combines a 40hz tone with music – sort of a meditative buddha thing. Much easier to listen to than what I purchased.

  • Colin

    A Google search suggests that the auditory range for rats and mice begins at 1,000 Hz. Assuming that these search results are correct, the rats aren’t hearing the 40Hz tone.

    Is the inner ear able to generate electrical signals from non-audible tones.. An analogy might be how the retina passes signals to the hypothalamus for non-visual, circadian functions..

    Or is this simply a matter of a different mechanical vibration detecting function, perhaps through the skin or viscera.

  • Bob

    Ive benn using your generator for about a month and I have noticed a difference in my mother who has Alzheimer’s .i turn it on for an hour to3 hrs a night at a low volume just discernible . My mother seems calmer, sleeps better and is less agitated/more cooperative. She also is better at regular daily activities like using her fork for the whole meal and not switching to her hands

  • Ellen Thomas/Tomas

    I plan on getting this information to the caretakers of people with Alzheimer and dementia people.

    I also know people with multiple system shut down.. And wonder what frequency would help them..

    Thank you so much for making you generator available to us

  • Joseph Kennedy

    I found your site and used the tone generator to see the range my tiny bluetooth speaker could produce, and also the range I can sing. I had a good time reading about the Alzheimer research, but laughed to death over the portal to Sedona. The comment about the guy being scared his kids will disappear through a portal had me rolling.

  • Helena

    Can one use earphones in order to listen to the 40hz on your generator or does it have to be speakers?

    Thanks!

  • Kevin in Waterford

    Is there any evidence yet that sleeping with audible 40hz has any value? And regarding 40hz light therapy, a simple stereo amplifier can run an automotive 12v LED lamp quite well. Synchronization with the sound would be assured and a stereo amplifier can use the balance control to set the ratio between sound (channel 1) and light (channel 2).
    I found the szynalski.com tone generator long ago, using it for other testing, but just now heard about the 40hz research. This is incredible. My father passed from Alzheimer’s so I have a pressing interest myself. I’m 56.
    Thank you.

  • Francis Cagney

    Is it possible to use this software to generate a beat? The javascript is obfusticated but I can see it is not filling a buffer with sin waves.

    If you multiply a 40Hz tone by a 1000Hz tone you are effectively modulating the 1 KHz carrier with 40Hz. Dual side band suppressed carrier analog modulation.

    It is the simplest form of modulation. Note if the modulator was 1 + cos(2 PI f) going from 0 to 2 the carrier would not be suppressed.

    If you looked at the spectrum with suppressed carrier you would see spikes at 960Hz and 1040Hz. If the carrier was not suppressed there would also be a higher spike at 1000Hz.

    Look at Analog modulation methods on https://en.wikipedia.org/wiki/Modulation

    The ear will demodulate so you will hear both the carrier and 40Hz tone.

    One reason for modulation in the RF world is because it is easier to send higher frequencies than lower. A more important reason is to divide bandwidth between users.

    It is also easier to send higher audio frequencies so modulation could be a technique to get more 40Hz sound over a PC speaker.

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