Things I’ve learned, published for the public benefit
Hope This Helps header image

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. Flickering at 20 Hz and 80 Hz 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.
  • 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.
  • In January 2017, Cognito Therapeutics, a company formed by some of the members of the MIT team, started conducting preliminary trials to assess the safety of exposing AD patients to simultaneous flickering lights, an audio tone, and vibrations – all at 40 hertz.
  • In January 2018, the New Scientist reported (paywalled article) that 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 would be 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. According to the magazine, these results were presented at the Society for Neuroscience conference in Washington in November 2017. However, the published paper described a significantly different protocol (see below), so it is likely that the New Scientist didn’t get the details right.
  • In July 2018, the International Journal of Alzheimer’s Disease published the results of a pilot study in which 6 human patients were exposed to a 40-hertz flickering light bulb for 2 hours a day for 10 days. The therapy was administered in a home setting by the patients’ caregivers. No difference in β-amyloid plaque was found after therapy. If there was an effect, it must have been smaller than 20%, which is not comparable to the 50% reduction seen in mice.
  • In March 2019, Cell published another (paywalled) paper about another study done by the MIT group. Here’s a NYT article about it. Here are the main points:
    • After mice were exposed (for 7 days, 1 hour a day) to a series of clicks repeating at a frequency of 40 Hz, the amount of amyloid plaque in their auditory cortex and their hippocampus was reduced by about 40%. The mice also did better on several tasks involving the use of memory.
    • The clicks were 10 kHz waves, 1 millisecond long, repeated 40 times a second (each cycle had a 1 ms tone followed by 24 ms of silence). In communication with me, one of the paper’s authors said that pure 40 Hz tones were not used because mice cannot hear tones of such a low frequency.
    • When this auditory treatment was combined with light pulses at 40 Hz, microglia (“brain cleaner cells”) started clustering around amyloid plaque, and the reductions in plaque extended to parts of the prefrontal cortex (an area related to functions like attention and short-term memory). This effect was not observed with either audio or light treatment alone.
  • In 2018, Cognito Therapeutics started three clinical trials of their device (called “GammaSense”) that combines visual and auditory stimulation. The device is essentially LED goggles with over-the-ear headphones.
  • [NEW] In 2019, Dr Tsai’s MIT group started two small trials of another device – a white screen illuminated with LEDs flashing at 40 Hz combined with a soundbar emitting a 40 Hz “buzzing” or “humming” sound. Here is a summary of Dr Tsai’s presentation on it and here are the pages for the two trials on
  • [NEW] In April 2021 at the AD/PD conference, Cognito presented preliminary results of the GammaSense trials, most notably, the Overture trial (news story from, which is designed to evaluate efficacy. 46 patients with Alzheimer’s Disease received a daily 60-minute session with the GammaSense device for a period of 6 months. The control group comprised 28 patients who received sham treatment (i.e. a placebo-like device that isn’t supposed to do anything). The study seems to tick all the boxes for good scientific research: it’s randomized and multi-center. Although it’s not strictly double-blind, the subjects, their caregivers and the people who rated the patients’ cognitive functions were blinded (i.e. they did not know who has received real treatment and who the sham). Back when this trial was announced, I wrote that it was rather small and the only way it could show anything is if the device had a large effect. Well, the results are decidedly mixed, and I can pretty confidently say that GammaSense didn’t have the sort of huge effect everyone was hoping for. There was no significant difference between GammaSense and placebo on 3 out of 5 cognitive tests used in the study, and GammaSense came out slightly ahead on two of them. Brain tissue loss also seemed to be slower in the treatment group, though that doesn’t have to mean anything, considering that the control group was older than the treatment group. I would definitely like to see a proper, peer-reviewed paper rather than just a presentation – someone should go over Cognito’s work and make sure the results are statistically valid. The researchers collected amyloid PET scans, CSF, and blood samples, but have yet to analyze them. I do like the fact that cognitive function was assessed, not just amyloid deposits – we already have experimental drugs that remove β-amyloid, but don’t do anything when it comes to actual dementia. Too bad the results have fallen short.
  • Cognito is not giving up and has announced another, larger study, which is to start in the second half of 2021.

Further reading/listening

Update from Dennis (March 2020):

I’ve gotten in touch with Dennis Tuffin to ask about his long-term experiences with 40 Hz therapy. Here is his response:

I reached a point when I knew that my wife’s condition was worsening so after [about 8 months] I gave up using the sound treatment. (…) My wife was already losing verbal capacity and was decidedly becoming slower in her movements, so it’s not the case that stopping the treatment caused these things as they were already happening. I was enthusiastic about it, because there appeared to be a noticeable improvement in her capabilities for that 8 or 9 month period, so noticeable that it was remarked on by almost everyone that she knew. So I am still sure that it helped, if only for a limited period and I think that it’s also likely that if it had been applied from the beginning of her diagnosis it may have had an even longer lasting effect. I’d still say give it a try – it costs nothing.

Dennis also told me that he had recently learned that his wife has vascular dementia in addition to Alzheimer’s Disease. I mention this, because that fact might have some bearing on the effectiveness of sound therapy.

(Don’t) try this at home

Let’s say you are not dissuaded by the lukewarm results from the Cognito trials. You’ve decided that you’ve got nothing to lose and you want to try some kind of do-it-yourself auditory therapy. What kind of tones should you use?

Dennis, the reader from the UK who piqued my interest in this subject, used a pure 40 Hz tone.

According to this AlterNet article (later reprinted by The Salon), a pure tone was used in the preliminary safety study done by Cognito in early 2017.

It appears that the most recently published MIT study on mice used series of clicks (despite previous reports) rather than tones. The New York Times quotes Dr. Tsai, who worked on that study, as saying “your brain seems to be able to perceive clicks more than a tone”, which would seem to indicate a preference that’s not exclusive to mice. However, in response to my inquiry, another co-author of the paper, Ho-Jun Suk, said that 40 Hz pure tones were not used because mice cannot hear tones of such a low frequency.

The New York Times and the Boston Globe published articles about the MIT mice study, including links to audio samples of the stimuli that were used by the researchers. Unfortunately, I have discovered that neither sample represents accurately the audio waves that were played to the mice. The clicks in the published samples are smeared in time (closer to 2 ms) and are not pure 10 kHz tones. Ho-Jun Suk has confirmed that they do not match the source signal. (I don’t know how the NYT and Boston Globe managed to mangle the files so badly, but it’s not because of compression – I tried it on the same encoder and the same parameters that were used by the NYT and it did not distort the signal very much at all.)

This 2021 report from Alzforum uses the words “hum” and “buzz” (interchangeably) to describe the sounds used in the two ongoing MIT trials of the screen+soundbar device. This would seem to indicate that those trials use a pure 40 Hz tone, as a series of clicks doesn’t sound like humming or buzzing. Furthermore, it is reasonable to assume that if the researchers wanted to play a simple series of clicks, they would have used a smaller and more economical speaker, not what is described as a “high-fidelity soundbar”. However, the same article uses the word “buzz” when discussing the 2019 mice study, and we know that one used clicks, not tones, so we should be careful about how much we infer from the phrasing in that particular report.

If you are thinking about using clicks rather than pure tones, I would not recommend using 10 kHz clicks because human ears are not very sensitive to that range of the spectrum. Something like 3 kHz (where human hearing works the best) would probably be more sensible.

It would be very interesting to know what sort of tones are being used in the now ongoing human trials. (If you are in the trials or know anyone who’s in them, please let everyone know in the comments section.)

Technical advice for playing pure 40 Hz tones

A series of clicks is not particularly demanding – it can be played on anything. If you want to try playing a pure 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, and in fact headphones were used in the initial safety studies commissioned by Cognito. 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 (, 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.

180 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.

      • Gregory

        Sorry about the delay here on my end.

        I’ven’t seen a reference here to yet – so there it is.

        Yup, my Mom plateaued, too. BUT, we still think she’s better than she was, & might have improved a bit as well — it’s been about a year. Of course, we’re getting right up there in years ourselves & have found it difficult to maintain a regular application of this therapy over the ensuing mos. (Another abbre. for you, Tomasz 😉

        Given the contents of the article above & some of the comments below, we’re looking into constructing a visual component for her Tx soon. And, recently we all (Dad: 95, we: 70) started tossing some EGCG standardized extract down the hatch ea. morn.

        Pls keep up the ‘good’ work everyone.

  • 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.


      • 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.

    • Danny

      Hi there. With regard to synchronizing of sound and light at 40hz, I am aware that quite a few people are combining the two, including me. I’ve also read that slightly out of phase elements can actually be more stimulating and effective in terms of entrainment, as it encourages the brain to interpret and correct.
      When looking at a low frequency bass sound at 40 hz, it seems to me that the point of the wave form being calculated by the brain can be almost anywhere. Is the brain listening to the initiating beat (40 per second) or the end of the beat, or the middle of the beat? If you provide light stimulation at 40hz as well, the same questions can be asked. I would assume (I know what they say about ‘assume’) that the brain is able to phase correct and synchronize sound a light, with the ‘dual’ inputs of sight and sound reinforcing entrainment.
      What do others think?

  • Garth

    I think the website/product Stockett referred to is 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

    • Arlan Giem

      I recommend the headphones from “CAD”model MH310 … they cost about $40 and there is no equal to them in that price range…They easily reach 40hz… It feels more like pressure than tone…. Your standard audio sources should be fine.

  • Garth

    Sorry to bother again – since posting I found this website
    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?


  • 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 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

    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.

  • Itopa Asher Anumah

    I have ADD. And although its not as serious as alzheimer’s it has ruined my life. I have been doing poorly in school and life in general due to not being able to pay attention, lack of organization and motivation. I have read about using brainwave entrainment especially Isochronic tones in the beta or gamma frequency to manage ADD as they basically boost dopamine which people with ADD lack. Also I have read that gamma frequency of 40 Hz can increase productivity similar to Modafnil and Adderall. Some even go as far as to say that 40 Hz frequency can create effects similar to NZT in the Limitless movie. All I know is 40 Hz is like the operating system in the brain. If it helps people with alzheimers improve it can probably make healthy people smarter.

  • James Vining

    I just ran across this article, what kinda sucks for me is my dad lives in SW Washington and I live in Milwaukie, Oregon.
    I just found this info today 12-13-18 and my system I have (Custom Built) consists of Two Peavey CS (Commercial Series) Professional 1000X Amps Bridged each powering a 15″ Sub with X-over setting at 120 Hz and a Peavey CS 800X Powering the Mids and Horns (Each Cabinet has One 15″ Sub, Two 5-1/2″ Mid Range Speaker and One Horn.
    I have the ability to make my eyes water and the windows sound like they are falling out with minimal distortion (not sure if the Vibration internally has some ability to improve blood flow and break up the Plaque that supposedly is behind the condition but I am planning to build something to take to my parents so my dad can try this 2-3x a day for 30 min each day.
    I know in the past 3 years or so he has went from beginning stages to advanced and now cannot drive much further then the town they live in where he used to be a semi driver and drive allover the state and in the crazy crowded streets of Portland Oregon so I am figuring anything that will help him gain back some of his old self and help him enjoy his retirement is well worth the effort on my part to set it up.
    I will be sure to keep all informed of what setup I build and any improvements etc.

  • Anon

    No such effect in humans (though small cohort and short time-frame):

    • Tomasz P. Szynalski

      Thank you for the link! It’s still too early to say anything, but the study certainly casts doubt on how well the results from genetically modified mice will translate to non-genetically-modified humans.
      I have updated my write-up to include a summary of the paper. Also added information about the three Cognito Therapeutics clinical trials (with audiovisual stimulation) that are underway right now. We should know more when they publish the results; I’d guess in early 2020.

  • Ted M.

    I am a retired Japanese engineer, and have “a very initial subjective symptom”.

    For the past 1 month, I have been stimulating myself by ”40 Hz LED light (visual)” and ”Hi-Fi audio earphone for continuous sine wave 40 Hz sound (auditory)” for 1 hour every day.
    I made this device by myself, so the stimulus intensity is tuned up in order I feel comfy.
    At present, significant improvements have been obtaining on my symptom of “frequently falling over in the night, in the dark”.

    As the next step, I am going to start next experiment to expand the region of the brain that receives stimulation. In other words, I made a next prototype device to produce a comfy intensity of 40 Hz vibration stimulus to the “palm” and “fingertip”. And I began to use it together with stimulation of the mentioned light and sound.

    After I use “the four stimuli device”, I feel “a strange exhilaration feeling on fingers, hands, stomach and intestines”, so it seems that the 40Hz stimulation is reaching to the parts other than the visual and auditory sense in the brain.

    Do you know any published papers on what kind of effect (or adverse effect) is clinically related to giving such four stimuli at the same time?

    • Tomasz P. Szynalski

      Sorry, I’m not familiar with studies on touch stimulation. These are very recent findings, and research is still in the early stages.

      • Ted M.

        Thank you for your kind comment.
        As you pointed out, research in this field is an early stage.

        I think that it will take a considerably long time until clinical study of a large number of cases and statistical completion of a new therapy. I will make effort to alleviate the progress of my own symptoms as much as possible until official medical technology improves.

        Furthermore, according to recent study on brain science, there is also research that “some meditation technique supply gamma brain waves of 40 Hz throughout the brain.”
        I hope the professional clinical researchers also note attention to this new field of brain science.

        • Ted M.

          I have received several inquiries to my Facebook “Nightstar Morningbird” etc.
          As I think that it would be in the public interest, I make my answer public.

          The four stimuli device includes a drive circuit and a “3 dimensional shaped sinusoidal 40Hz vibration devise”.

          The purpose of the “3 dimensional shaped sinusoidal 40Hz vibration devise” is:

          1) Stimulate your palms and fingers of both hands at the same time.
          2) Move the palms and fingers to feel and enjoy the change in the resonance condition of the vibration device.
          3) Estimate and enjoy the change of resonance condition by using vibration devices having another 3 dimensional shapes.

          In this way, you can feel, think and enjoy the 40Hz vibration on palms and fingers.

          The drive circuit of this device also incorporates a 40 Hz LED flicker light source with square wave current drive and a function to drive high-quality-audio-earphones with a 40 Hz sine wave.

          The waveform of it’s sound source is a sine wave of 40.0 Hz exactly.

          The “3 dimensional shaped sinusoidal 40Hz vibration devise” consists of three parts

          A: Driving device
          Ultra right weight 40Hz electro-magnetic vibration device which is driven by electric current. I purchased this by mail order in Japan.
          However, in order to properly drive this commercial products at 40 Hz, it was necessary to re-design the current bias characteristics and other characteristics of the drive electronics.

          B: 3D plastic statue
          Lightweight, moderately flexible statue object.
          The shape is selected to have resonance characteristics appropriate for my experimental level.
          At the moment, I use plastic containers and plastic dishes sold at “100 yen shop” in Japan.

          C: Connection means
          Connect the above-mentioned Driving device and 3D plastic statue.
          Using this parts, I can change and swap out multiple 3D plastic statues.
          The connection means which can change the connection for an unlimited number of times is packaged as an accessory part of the above-mentioned Driving device. So, it is free of charge.

          Since I am a retired old researcher in the field of robotics, I can present detailed experimental specifications and videos like academic papers and make them available to the public for the benefit of the public.

          • Ted M.

            I found a patent application for the prevention of Alzheimer’s disease that combines 40 Hz light, sound and vibration.
            I inform it to everyone for the benefit of the public.

            Number: WO-A1-2017/143128
            Country of application: US
            Application Number: US2017 / 018277
            Application date: 20170217

            Paragraph [313] and [0314] of this patent states that 40 Hz light, sound and vibration will be applied to Alzheimer’s and Dementia patients.
            It also states that the more than one stimuli may be coordinated such that they all occur in sync or out of sync, depending on the therapy, person and situation.

  • John

    How about placing the headphones on the side of the cranium above the ears.
    The tones would impinge on the skull and would not irritate the hearing apparatus.

    I tried the phones on the head and varied the pitch.
    At one frequency I got an unusual sensation in one of my teeth.

    Hope is that while thinking of an individual I know, but whose name doesn’t float to the surface, while slowly moving through the range, there’ll be a pitch where the name appears.

    Maybe the same approach will reveal a frequency for relieve of migraines or tension headaches

  • John

    I placed the headphones perpendicular to the normal orientation – one on he forehead and one on the back.

    The names of the contacts came to mind immediately. Is this real or simply a natural delay?

  • Katrina

    Thank you so much for posting and sharing this.

    I tried playing the tone on our subwoofer and turned the volume on the subwoofer way up and it blew the subwoofer. 🙁 I’m not an audiophile or even remotely close to one. I guess that it’s because I turned it up to high? Let this serve as a warning to anyone else inclined to try this. Dying to test this out on my husband who, at 52 years of age, seems to be developing early alzheimers. Crossing my fingers that this can help. Since I don’t know how or even if I can fix the subwoofer, I guess that I’ll go for the second best option and try this on our speakers. Wish me luck and feel free to send me pointers. My email address is

    I will provide feedback as soon as I can test this out.

    • Katrina

      I have some great news to report. I bought a TENS 7000 unit on Amazon for $27 and applied the patches to either side of my husbands collar bones, aka his vagus nerve, set the device for 40hz and did a 30 minute treatment and reversed his aphasia almost 100% in one treatment! It was only temporary for a couple of weeks but we simply do another treatment when he needs it. It’s amazing. Our functional neurologist told me to get the ear clips and to clip them to the hard part at the front of the ear to get the vagus nerve that way.

      BTW – I had the dial waaaaaay down on the TENS unit when I did the treamtent. He could barely feel it. I was at about 1 on the dial.

      My husband has Alzheimer’s and was having trouble speaking.

      I’m still trying to play the 40Hz sound. Bought a new subwoofer but I can’t hear anything. Not sure if the subwoofer works or not. Going to try headphones.

      • Tomasz P. Szynalski

        Interesting. Thank you for sharing the report. Does this work if you use another frequency, e.g. 80 Hz?
        Regarding the subwoofer, does it work when you try to play a higher frequency? For example, 100 Hz? If not, it’s probably set up incorrectly.

      • Matt

        I was laughing when I heard you blew out the subwoofer! If you put your hand on the subwoofer cabinet (or better yet, lightly on the woofer cone) you should actually feel the vibration of 40Hz-which is the lowest note on a bass guitar. You probably don’t need it loud. And from my reading, stick with 40 Hz.

  • Nancy

    After reading the NYTimes article, I found your website. So, if I may ask, how/where do I get a clicker?

    Researchers hope the techniques can be applied to help people with Alzheimer’s.

    Read More… A Possible Treatment With Clicks and Flashes? It Worked on Mice

  • Stu

    Do you think listening to a 40hz tone would clean up the brain in CTE patients, as well?

  • Jim

    I’m a little confused about the waveform/frequency. I wrote an email to the corresponding author of the Cell article and he replied that they used a 40 hz square waveform. But as mentioned by someone else, that really will sound like 80 clicks per second rather than 40. Should I write back to the person and ask him?

    • Tomasz P. Szynalski

      If they used a 40 Hz square waveform, that would mean they lied in the article. The article very clearly specifies 1 ms clicks followed by 24 ms silence (which adds up to 25 ms = 40 Hz). I think it’s possible the person you were talking to is simply uninformed as to the acoustic details. Or they were thinking about a different study (the human clinical trials being done by Cognito?).
      PS. If you wrote to Dr. Tsai, she’s female.

      • Karen

        Thank you for all of this information! My mother died of AD and I’m trying to take preventative measures for myself. Do you have recommendations for a particular subwoofer that’s not too pricey? Also – now I’m thinking about whether I should use the tone or the clicks… do you have suggestions, and what is the best way to listen to the clicks? Thank you!

        • Tomasz P. Szynalski

          Hi Karen,
          Sorry, I don’t really have a lot more to say. Any decent-quality subwoofer should do 40 Hz better than a normal speaker. With regular stereo systems, it greatly depends on the “bass extension” of the speakers, which is correlated with the size of the largest membrane. As I explained in the post, you can also boost the bass by placing your speakers strategically, which would probably be the cheapest option if you already have a stereo system.

          However, the latest protocol uses clicks (the researchers don’t explain why) and who knows what they’re using in their human trials. And of course, who knows if it will even work on humans. So maybe it’s best to just wait a year or so.

          • Karen Klein

            Thanks so much Tomasz. For now I’m listening to the tone on good quality headphones that we have. Look forward to seeing what else comes up on here. This does give me hope.

        • Tom

          Hi Karen,

          I asked the creator of the Tone gen Pro app:

          to implement the ability to duplicate the exact same kind of tone used successfully by Dr. Martorell in their research:

          Their latest version of the app has the feature, which they call ‘Clicks’. As Mr. Szynalski says, the tone is 1ms of clicks followed by 24 ms of silence. In their research, Dr. Martorell used a frequency of 10 kHz for the ‘on’ tone (i.e. the clicks that are played for a duration of 1 ms). I believe this was chosen since the test subjects were mice and that frequency is in the middle of their hearing range.

          For humans, I would choose a frequency of 2 kHz, played for 1 ms, followed by 24 ms of silence. This is effectively a 40 Hz rate with a 4% duty cycle.

          To get this using the ‘Clicks’ feature in the Tone Gen Pro app, set the ‘on-off’ frequency to 40 Hz, the ‘on’ frequency to 2000 Hz and the ‘on time’ to 0.001.

          I hope this is helpful.


  • stewart B

    We are currently experimenting with a subwoofer and sound to treat ALZ.
    40Hz seems to be the ideal frequency, but there are so many ways to get there.

    I have found some good info from here:

    They talk about modulating the sound. For example, a 460 Hz carrier wave with 40 Hz modulation was produced by superimposing 440 Hz and 480 Hz sine waves.

    There is a related EEG study used on skin stimulation, that could show avenues to think about:
    ” The stimulation pattern consisted of a 200 Hz sinusoidal carrier modulated by either a rectangular signal of the stimulation frequency (called the sine tap stimulus) or amplitude modulated by a sinusoidal carrier (called the sine am stimulus)”

    If you want to try modulting two sounds together try here:


  • Oscar

    I’ve read through all the comments and am touched by the heartbreaking accounts of people trying to delay the progress of this dreadful decease on their loved ones or themselves. My wife is now in a home. I tried for ten years with all the knowledge I had at that time, meditation, coconut oil, anti-inflammatory foods, sunlight, vitamins, long walks, exercise on the rowing machine etc etc. With great sorrow I had to watch her go into a home where I could not intervene except to visit her. So the stories told by other people touched me to my core. Keep up the progress you guys, and thank you very much for the article Tomasz. Very informative and it gives us all hope.

    • Thomas

      Oscar, I read your comment and felt compelled to reply. I feel like I am on the same walk you have been on. My mom is in the early stages and I have tried everything I can. I don’t know if any of it works or not. I do know this.. when we try to help it is a reflection of our humanity that we want ‘to heal’… I am going to continue to walk the path and navigate all of its curves. I hope this finds you well. bottom line.. you are not alone.

  • rebecca gonzalez

    My mother had 4 siblings. She and two others developed Alzheimers. The other two died at yoinger ages and hadn’t reached the point whee Alzheimers was detectable.

    Thank you for this information. I have signed up dor clinical trials and am hoping that the Biggs Institute at the University of Texas Health Science Center in Sam Antonio will undertake visual and sound trials of this nature.

    In the meantime, I will try your suggestions and hope that I notice some differences in myself.

    I did see that the AlzLife App is available via ipad. However, I have androids and an IMAC and the app hasn’t been made available through these devices.

    Please keep me in the loop.

  • Karen

    Thank you for this! I wrote a comment as a reply but don’t see it so I’m writing again here – apologies if it came through again. I have a few technical questions. First, do you recommend at this point using the tone or the clicking sound? If the clicking sound, what’s the best way to play that? If I use the tone, does anyone have a recommendation for a subwoofer that’s not too pricey? Or, is there a way to play the tone on a regular stereo? Thank you for all this information – my mother died of AD and I’m trying to take preventative measures for myself. This is such a devastating and scary disease – as others have said we definitely need to use all the tools we can muster.

  • Fiona

    Has anyone used the “AlzLife” app yet and received results? I see that it is counterindicated if there is any history of seizure or macular degeneration. Could the light therapy reduce vision? Which would not be good. Has anyone had success with it?

  • Jason

    I want to try this properly for my mother who has had Alz for 6 years, but I am still confused as to what tone to use (sawtooth vs sine)? Also it would seem to me that headphones would be the most effective.

    That being said, I used,saw on myself which was quite difficult to tolerate after about 10 minutes on the headphones. When I finally stopped, I had a strange ringing in my ears for a couple of minutes. Too loud, perhaps?

    Please give me some ideas and I will post back here with the results. My mother is forgetting a lot of common words so it would be very easy to detect improvements in her, and she is very cooperative so an ideal patient.

  • Robert

    In Dr. Tsai’s experiment, the key was not a 40 Hz tone, but, as you wrote, 40 clicks/sec. with a supposed duration of 1 millisecond (ms) and a tone of 10 KHz. Perhaps someone can build a “clicker” with the one constant being 40 clicks/sec., but with tone frequency (e.g., 250-2000 Hz) and click time (e.g., 1-10 ms) being variables. It could be that humans respond best to a particular frequency or range of frequencies at each click and a certain duration of click.

  • RS

    Have been looking at the iPad Pro 10.5″ and iPad Pro 12.9″ in order to utilize the Alz Life App which includes the sound and light therapy. (These two iPad Pro models are the only ones with the 120Hz refresh rate which would enable the light therapy to work.) Wanting to use it for my 93 yo mother with dementia as well as my hubby who has Parkinson’s like symptoms. Seems like this should work if it helps produce gamma waves and raises dopamine. Thanks, Fiona, for the info on the app! Has anyone else used the sound/light therapy or the Alz Life App for Parkinson’s?

Leave a Reply to Ted M.