DIY Flanagan Neurophone Lets You Hear With Ultrasound

[Andreas] wrote in to let us know about this DIY Neurophone project. Apparently a Flanagan Neurophone uses ultrasound in some manner to transmit audio directly to the body, or nervous system? Needless to say we are a bit skeptical of anyone whose wiki page leads directly to pyramid power. In fact most of the references to this thing start rambling about some pretty pseudo-scientific theories.

At any rate, the schematic is clear and simple enough for anyone who has the parts to easily try.  The only challenge might be tuning the thing with a signal generator or audio feed. So how about it, any one have a TL494 pulse-width modulation controller and want to be a guinea pig?

85 thoughts on “DIY Flanagan Neurophone Lets You Hear With Ultrasound

  1. No need to be skeptic, since there is no magic here. It already exists and is sold : http://www.holosonics.com/technology.html
    I tried another brand (I don’t remember the name) and the results are very impressive : highly directive sound that can only be heard when the speaker points at you.

    It is even used on military vessels as pirates repellent (since the USS Cole bombing AFAIK)
    http://en.wikipedia.org/wiki/Sonic_weapon

    1. Yep, it’s 100% legit. I’ve got one of the knockoff “grok boxes” from back in the early 90’s and a legit Neurophone from Flanagan himself. The knockoff works but not as well as Flanagan’s. If you look around you can find several different sets of schematics for them with different abilities. They’re very cool for learning.

      1. There is another method that falls into the “hey kids, don’t try this at home!” category. Circa 1972, several experimenters were using micropower frequency injection with conductive pads, one applied to the lower back and one applied to the neck/shoulder area.

        Caveat: I haven’t done it, I did not see the demo and the idea gives me the heebie-jeebies – I ain’t trying it. The modulation was at high frequencies, and the audio signal was somehow pulled out by the CNS. I believe there was another variant that simply had two pads near the lower back.

        Although I know nothing of what happened to the project, I know that it was used successfully to send audio cues to individuals without the use of headphones. And I don’t mean “tin-foil-hat brain control” cues, just regular speech at low to medum fidelity.

        Another interesting project was using two reasonably high power narrow beams of ultrasonic audio to heterodyne at a location, which would mix and be filtered by humans as speech or music. It’s a cool party trick with no particular application, and you can do it home using ultrasonic frequency shifters.

        You can also go the other way. Look into infrasonics – it turns out that elephants (and I think whales do as well?) communicate at very low audio frequencies just as bats do at high frequencies. The data rate drops, but really, there’s a lot you can do at <20 hz… and in the RF bands, there are lots of folks moving data around at glacial speeds for various reasons.

        1. His original patent (US3393279) uses electromagnetic waves. it’s basically a radio transmitter that could be picked up by the human nervous system. It modulated a one-watt 40kHz transmitter. Over a decade later, Flanagan came up with a version of the “Neurophone” that didn’t use radio (Patent US3647970).

          1. My understanding was that the US3393279 patent used electrodes that induce a current in the body mimicking the pulse train of neurons, the 40khz was the carrier frequency which is pulse density modulated with audio of whatever source. The coil in Fig. 4 was just another way of inducing current. Patent US3647970 uses piezos & is probably just a form of bone-conduction audio.

        2. This shows that the unit can operate in two different ways, inducing modulated electricity in the brain, from electromagnetic waves, and using ultrasound as bone conduction. There is no secret in the operation of this device.

        3. The audio signal is modulated as a message in an electromagnetic wave pattern, equal to any radio wave.

          Patent US 3393279 – Nervous system excitation device
          “The electrodes 1 are electrically connected to a source of modulated electromagnetic waves inclusive of a radio frequency power amplifier and variable frequency oscillator, indicated in box 3, an audio modulator, indicated in box 4, a source of audio signal, indicated in box 5, and a power supply for the signal source, modulator and amplifier, indicated in box 6”.

    1. AFAIK, sound is modulated on an ultrasonic carrier wave that is dismissed on “hard” objects (e.g. head bone). I’m no expert though (obviously)

    2. (mods, clicked the ‘report comment’ link instead of ‘reply’ by accident. Sorry!)
      Here’s the mode of operation (mostly copied from my comment below):
      – It replaces the rising and falling edges of the audio signal wave with edges that have the _slope_ of a 40-50kHz ultrasonic wave. The 40kHz carrier is unimportant, the slope is key.

      – It then double differentiates and highpass filters the result. This mimicks what would happen if you fed the signal into an antenna and then received the electromagnetic waves with your brain! The double-differentiated signal is now converted to mechanical energy with a piezo speaker, bypassing the brain’s radio receiver.

      The way the piezos are wired in the TL494 Neurophone (maybe also in the real ones) creates an electrical “Lilly Wave” that stimulates the nerves as if they were getting signals from other nerves.

  2. I love it when pseudoscience debunks itself:

    “Lastly, you’ll probably find the signal is easiest to hear ‘in your head’ with the electrodes near your head.”

    Exactly. Because what they’re claiming, that it’s picked up and transmitted by the nervous system to some “little known part of the brain”, isn’t true.

    Physical conduction of sound to the inner ear is well known and documented. Most folks can hear up to about 30khz or so if the transducer is pressed against the head. And modulated ultrasonic carriers will be partially demodulated, which is the only reason this works.

      1. It works to a limited degree, just not as well or in the manner claimed.

        Even if the bones in the ear are fused or damaged (resulting in deafness) you can bypass them by transmitting amplified sound through the cranium to the cochlea. I believe there’s commercial hearing aids that work on this principle.

        But Flanagan said that using this device, any nerve can pick up sound, transmit it to the brain, and the user can hear it. Just not true, sorry.

        1. Not quite true. I actually made one of these and used it. By using the piezos not as contacts, but separate and using foil pads (because too wasn’t sure if it was just vibration from the piezos themselves), it still worked.
          The piezos are to limit current and dc voltage, so they needn’t be the contacts themselves.

          1. I know this is old, but the Neurophone interfaces with the saccule. The cochlea can be completely missing and if the saccule is intact the individual will “hear” the ultrasonic frequencies coming from the transducers. In fact, when Flanagan was applying for his patent the patent office told him if a certain deaf patent inspector could hear using the Neurophone they would award the patent. For the first time the deaf patent inspector heard classical music and wept. The patent was awarded only to have our wonderful government attempt to classify it which Flanagan successfully fought and won his right to the technology. The saccule gland has a neuronal connection to the brain, both to the hearing center as well as to the long-term memory and the subconscious. In 1991 a scientist, Martin Lenhardt, discovered the foundation of this transmission path for ultrasound. We share this ultrasonic “hearing” ability with dolphins.

        2. The nerves most certainly do transmit information that simulate sound processed by the brain. You can demonstrate this by placing the transducers down your spine and the effect is profound.

  3. what would actually be cool, but hard, would be something that takes ultrasound and steps down the frequency but preserves other sound characteristics so it can be heard. The audio equivalent of ultraviolet film.

    1. Have seen that before. Think there was a project for it in an old issue of Radio Electronics, that would let you listen to bats, insects, freon leaking from pinholes, etc. It’s a matter of heterodyning, same way a radio shift RF frequencies down.

      1. POTS cables are pressurized. a long time ago a long haired man was walking down the alleys & streets wearing headphones with a parabolic reflect pointed towards the sky, am odd sight in a small town. I stopped to ask what’s up. He said he was with the telco & was listening for the ultrasonic sound made by gas leaking out of fin holes in the cable armor.

      2. you write: “POTS cables are pressurized. a long time ago a long haired man was walking down the alleys & streets wearing headphones with a parabolic reflect pointed towards the sky, am odd sight in a small town. I stopped to ask what’s up. He said he was with the telco & was listening for the ultrasonic sound made by gas leaking out of fin holes in the cable armor.”

        Not *all* POTS cables are pressurized. Apparently, that hasn´t been used in ages… must be really really old cabling…

        Ten years ago this was written:

        http://ecmweb.com/content/understanding-air-pressure-systems-osp-cabling

        “As an OSP system designer, you must be prepared to encounter *older system designs and outdated, but operable, technology* on any future project. ”

        “BICSI’s Customer-Owned Outside Plant Design Manual is a good source for referencing this *obsolete*, but very important, method of OSP cable protection.”


        “Most conduit routes that feed metropolitan areas still use air pressure systems to protect their cables. The high cost of replacing these large cables would make it difficult to completely eliminate such systems, so it’s more cost-effective to maintain them. Advances in air pressure system technology have changed all of that, though. The introduction of plastic insulated conductor (PIC) insulation and filled cable designs has eliminated the need to build or add additional air pressure systems onto a network.”

    2. Not hard at all if you do it with brute force: 192kHz input sound card, ultrasonic-capable microphone and a pitch shifter plugin. Shift 2 octaves down and enjoy. :-D
      Could do to a lesser extent with 96kHz.

      Heterodyning doesn’t do this, heterodyning only demodulates modulated signals but demodulating isn’t the same thing as listening (what you would hear would be a signal derived from the frequency shifts of the sounds, not the sounds).

      There’s no easy way to do it in analog as far as I’m aware. Certainly not with anywhere near the same quality.

      1. @hospadar – there are many heterodyning receivers to monitor bat calls that downshift while preserving character, e.g. http://bertrik.sikken.nl/bat/index.html

        @anon is mistaken. Any two waves (f1 & f2) multiplied in a mixer such as a LTP or diode ring will produce sum (f1+f2) and difference (f1-f2) outputs. If either happen to have sidebands (i.e. are modulated) these sidebands will also appear in the sum and difference signals. Heterodyning does not demodulate (except in the case of Direct Conversion receivers where demodulation is not required) and demodulators don’t heterodyne.

        See e.g.;
        http://en.wikipedia.org/wiki/Radio_receiver_design#Superheterodyne

  4. It does amuse me when people dismiss alternative theories just because it’s what the scientists tell us what we should do. I’d have expected that people on this site were a little more open minded towards new theories or thoughts. After all isn’t that how new inventions begin?

    1. We don’t dismiss them because “it’s what the scientists tell us what we should do”. We dismiss them because we KNOW enough science to enable us to realise that a particular claim or theory is bunk, or that it may work, but not in the way described.

      1. We know enough about science? Ha ha I’d like to think we do as well but it just isn’t the case I’m afraid. We have gaping holes within physics (which most academics will agree with) so how can we know enough about science?
        Anyway, I don’t want to sound like a conspiracy junkie.

      2. “We have gaping holes within physics (which most academics will agree with) so how can we know enough about science?”

        That’s appeal to ignorance, which is a logical fallacy. Not knowing something doesn’t make something else valid or true, or even plausible.

        “Anyway, I don’t want to sound like a conspiracy junkie.”

        But you still do.

    2. In science, the term “theory” refers to “a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.” It also has to make falsifiable predictions with consistent accuracy across a broad area of scientific inquiry, and production of strong evidence in favor of the theory from multiple independent sources.

      These alternative “theories” you’re talking about are just employing the Stetson–Harrison approach to science.

      1. I suspect that there are other websites for discussing this very topic so I’ll leave it at that. I was just surprised that people on this site were not open to other ideas that’s all. Just because we can’t detect something doesn’t mean it doesn’t exist.

      2. If you cannot detect, demonstrate, or otherwise infer the existence of something as being a part of reality, it is indistinguishable from something that does not exist.
        Therefore, you are unjustified in believing it to be true.

        If it cannot provide a falsifiable or testable hypothesis, it is meaningless conjecture.

        So, while I’m open to discuss possible hypothesis, I am also willing to dismiss without evidence that which is asserted without evidence.

    3. The Neurophone’s been around since 1958. It’s hardly new science, just bad old pseudoscience that resurfaces from time to time.

      And I’m not dismissing this because of what anyone tells me. In fact, I’ve built one. I speak from experience on what it can and cannot do, and that it doesn’t work as the inventor claims. Through that and other experiments, I eventually learned that “suppressed” inventions are utter nonsense at least 99% of the time; and I’ve looked at pretty much all of them. Hope you gain that wisdom eventually too.

      The only debatable science I still hold hope for is Lawrenceville’s fusion, Mach Effect thrusters, and Coolchips.

    4. “It does amuse me when people dismiss alternative theories just because it’s what the scientists tell us what we should do.”

      It doesn’t amuse me that you’re making this comparison; which is for me, absolutely false.

      You’re passing an argument based on ridicule which is almost as stupid as saying “i don’t like you because i just said so”.

      1. What annoys me greatly is that I failed to recognize a standard fallacy.

        Whether or not science has uncovered everything or not, does not make the original statement true. Nor is it remotely important.

        The burden of proof is STILL on the original statement holder.

        I feel like a complete idiot now :)

    1. Difference is that Flanagan claims the ultrasonics from the Neurophone can be picked up and “heard” by any nerve in the entire body.

      Holosonics certainly doesn’t make that claim. It’s real science, it works, and is picked up by the ear.

      1. See, and that is the difference I failed to pick up on when I was putting together the post. All the searches involving “Flanagan” and “Neruophone” were red herrings. Glad to know it IS real science… under a thick veil of pseudo.

  5. I wonder why the name for that “little-known part of the brain” was not given? In the event it’s known about brain scientists, it most likes has a name. I always figured science has long used block conversion/hetrodyning to learn about what sound does exist outside the human range of hearing.

  6. Bone-conduction technology using ultrasonics. Reading this would make one think that this guy didn’t know much about human anatomy, much less neurology. That “little part of the brain” is called the parietal lobe and it’s not that little.

    As far as how this would have worked with radio waves, most likely it was stimulating some of the muscles near the eardrum causing them to vibrate to produce sound in the ear. Kind of how your muscles could be stimulated to contract during an MRI. This may be the “nerves” they was talking about.

    1. Sufficient magnetic fields can, if placed correctly mess up some brain function. I recall a neat demonstration of a helmet, fitted with a high-strength electromagnetic coil, that would prevent the wearer from speaking properly when it was energized. They could still sing though, since it was a different region of the brain.

      1. I think I heard about that. IIRC they also used some called “the halo” to temporally incapacitate a person’s ability to read braille. The blindfolded person was unable to accurately read it after an intense learning session. They zapped their again and their ability was restored, if not a litte better, to normal. As for an actual blind person, no changes was even noticed. Imagine that.

    2. Having used a neurophone for many years I have been interested by this thread, especially since I am halfway through a science degree in my 50s. I am currently studying a module on the physics of hearing and have access to a university library I was intrigued to find out more. See article in Science, Vol. 253, 5, 1991, 82. Lenhardt for more information about ultrasonic bone conduction tested on hearing impaired and profoundly deaf subjects using, according to http://phisciences.com/rd/brain-waves, a duplicated neurophone. The researchers postulated that the saccule – not the parietal lobe – might be the mechanism by which these frequencies were detected. Interesting peer reviewed article which showed that even profoundly deaf subjects could “hear” words using this device.

      1. “Having used a neurophone for many years I have been interested by this thread, especially since I am halfway through a science degree in my 50s. ”

        Spiwiz, please upload a youtube video of you actually using your neurophone to listen to some real audio whilst describing what words sound like.

    1. JUST a Cochlear Implant without the implant? Pretty obvious you don’t have hearing problems.
      Implants destroy the Cochlea, ending any residual hearing.
      That’s why I have been profoundly deaf for decades and never got an implant. They don’t work for everyone, and if they don’t work, you are out of luck, whatever minimal hearing you had is history.

  7. It is a neat little gimmack. The key clue here is that he is using not just any pad of metal, but is using a piezo element connected to the piezo ceramics, not just the metal. The piezo effect is physically moving the piezo ceramics to make sounds just like the speaker that makes beeps inside your wrist watch.

    The trick is that it is using skin conductance touching on the metallic side of the piezo element to complete the output part of the circuit, so it won’t work until you press both against your skin. Then it simply becomes 2 piezo speakers in series. It you wire the 2 metallic sides of the piezos to each other it will work permanently.

    1. That is, if you wire the 2 metallic contact sides of the piezos to either other, it will work like plain old piezo speakers whether it is pressed against your skin or not.

  8. Kaj says:

    “If you cannot detect, demonstrate, or otherwise infer the existence of something as being a part of reality, it is indistinguishable from something that does not exist.
    Therefore, you are unjustified in believing it to be true.”

    So much win in so little text, I feel congratulations are in order!

      1. I second.

        “” If you cannot detect, demonstrate, or otherwise infer the existence of something as being a part of reality, it is indistinguishable from something that does not exist.
        Therefore, you are unjustified in believing it to be true.

        If it cannot provide a falsifiable or testable hypothesis, it is meaningless conjecture.

        So, while I’m open to discuss possible hypothesis, I am also willing to dismiss without evidence that which is asserted without evidence.””

        I copied that it was so good. Thank you.

  9. I’m mostly interested in the application for a “non-contact” hearing aid. I wonder how much power would be needed to project a sound beam for a hearing impaired person who doesn’t want to use a conventional hearing aid. Time to experiment…

  10. in order for this to work, the recieving brain needs a plugin!!!

    (code to redirect signals recieved from the spine into the sound module aka hearing)

    but of course, the manufacturer completely removed the service and diagnostic ports. looks like we need a redesign of the human body!

    updates for everyone! lolz

  11. Nothing at all bogus about the original Flanagan Neurophone; I built one in high school back in the early 80’s as for a school project. It really worked.

    However it didn’t use ultrasound directly. What it used instead was an interesting circuit that would generate a series of pulses which were conducted into the skin using special electrodes. While I suppose ultrasound might work just as well, it was not the way Flanagan did it.

    The theory was that the pulses looked enough like the way sound pulses coming from the inner ear do that the brain figures out that they must be sound and then routes them to the appropriate area of the brain for decoding.

    It is something similar to what someone with synesthesia (someone who can “feel” sounds or “hear” color) goes through all the time except this is an artificial form of it.

    I’ll be happy to dig up some details if anyone is interested.

    1. I know I’d love to know more about it!

      Could you correct me if I’m wrong, but I thought the original patent showed the device ending with a tank circuit with the electrodes working as the capacitor plates. Is that missing from this build or what? I’m not very good at reading schematics.

    2. I would be interested, I built the instructable and found that it did work but had to use a preamp on the audio input and could never get it loud enough, I am more interested in the effect of Hemi sync of the right and left brain hemispheres. I have tried using two signal generators 7 hertz apart in the range of 40,000 hz to create the alpha state to learn a new language. It puts me almost to sleep and I wonder If I am getting the benefit I was looking for or not. I introduce the hetrodine frequencies through the 4,000 hz pizo disk to my temples. and use earphones to hear the lessons.

  12. The TL494 Neurophone is indeed the wrong way to do it.

    It turns out Flanagan’s Neurophone does two things:

    – It replaces the rising and falling edges of the audio signal wave with edges that have the _slope_ of a 40-50kHz ultrasonic wave. The 40kHz carrier is unimportant, the slope is key.

    – It then double differentiates and highpass filters the result. This mimicks what would happen if you fed the signal into an antenna and then received the electromagnetic waves with your brain! The double-differentiated signal is now converted to mechanical energy with a piezo speaker, bypassing the brain’s radio receiver.

    The implication of this is that there are bits of our brain that act as a radio receiver with 100kHz bandwidth, and can process incoming audio. Which is crazy.

  13. Cross-posting from the blog, for all the commenters here interested in the updates:

    It turns out “earplug-style” (in-ear-monitor) headphones affect the brain in at least some of the ways a real Neurophone does. If you want the freedom of thought that the pink-noise Neurophone brings, an even more effective way of getting it turns out to be the following:

    Get some earplug-style headphones. Make sure they produce a good seal. One person used Sennheiser CX150s, which cost $18-30.

    Plug them into a pink noise generator. Use a good one! (Like this design: http://sound.westhost.com/project11.htm )

    And that’s it! If you want to sleep incredibly well, try this at night. A bit of medical tape under the ears will hold the cables in place.

    One heads-up: For maximum fidelity of the pink noise signal, it may help to use a headphone amplifier between the headphones and the pink noise generator. This is an easy-to-build design:

    http://headwize.com/projects/cmoy2_prj.htm

  14. Update: Maybe I wasn’t so far off after all. Neurophone inventor Patrick Flanagan has since confirmed the TL494 Neurophone design CAN produce Neurophone effects, though it’s still probably not as good as the real thing.

    Some research suggests this is why it works: the TL494’s square-wave output gets differentiated by the piezos (which are capacitors), producing a “Lilly wave”-like signal that mimics signals produced by nerves. (The Lilly Wave, as far as I understand, is a sharp positive spike followed by an equal but negative one. The idea is the first peak transports something, I think ions, across the barrier between nerves while negative spike brings them back so the nerves can use them again.)

  15. So after I have read all the comments.
    Has anyone successfully built a neurophone (this or another one)?

    I know that it works because about 10 years ago a neighbor, who has a company selling devices like this, gave me a demonstration.
    It was a demo for group synchronisation. We were 10 people sitting around a table. One of these persons put the pads on his skin. (I think it was put on the stomach)
    Then everyone held the hands of his two neighbors and everyone (including me) heard the music playing. He explained that the sound is conducted by the body liquids and the bones.

    So as I know for sure that its working, (Working defined as put electrodes on the skin and hear something no matter where the electrodes are placed)
    I want to build such a device!

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