I'm sure plenty of people on this site have heard of Patrick Flanagan's Neurophone (in short it allows people to hear through their skin) & was wondering if anybody here knows how it processes audio signals.

I would buy one if it didn't seem so terribly overpriced & I'd build one myself if I could get a complete schematic of it, but I think the availability of it could be broadened tremendously by simply figuring out how it processes an audio signal. From there the bulk of the device could simply be emulated using Audacity or similar audio-editing software.

*Here is a set of papers that describes in detail its history and functioning. The Rex Research page is also very informative (articles, patents, etc.).

*Here is a schematic. However, I cannot vouch for its veracity...As an aside, this website has some other interesting information on it as well.

If I am not mistaken, I believe the original version functioned through bone conduction. There are headphones (example) that will produce a similar effect.

I've read the patents & much of the other content on the rexresearch page before & there seems to be no sign that it works through bone conduction.

As for the schematic, it's as unreliable as it is difficult to decipher.

You are right! Thank you for pointing that out, and please forgive my error. After a little study, I think I might have figured out how it works. While the documents go into much more detail, I will try to give a very simplified summary as I understand it thus far.

Nerves can communicate in two ways:

*The electrical impulses change in length (a "firing rate code")
*The electrical impulses change in ratio to one another (a "temporal, or time, code")

The circuit turns an audio signal into these types of patterns and relays it to an electrode (or in our case, a piezoelectric speaker). Since our flesh is a liquid crystal, we can pick up this signal no matter where we place it on the body. Any nerve (not just those making up our auditory system) can interpret this information, therefore even the deaf (with inner ear damage) can "hear" with it. The sound shows up as a vibration inside one's brain instead of being picked up by the ears.

As for the schematic, I actually thought it was really neat how the author made a PCB-like layout in ASCII art. Although, I will admit it is somewhat tricky to decipher. Connecting the lines as described in the document produces the following:



And, I think it might be something like this:



I hope that helps. Again, I have not made or even checked this circuit yet, so I cannot attest to its validity. If you do decide to make it, be safe and good luck.

Thank you for the far more readable schematics. Did you make them yourself?

Admittedly I'm no where near as good at understanding schematics as I am at building things from them. I might build this if I could get my hands on the right components any time soon, but I mostly just want to know what the circuit is supposed to do to the audio input. I know the first thing involves square waves somehow, I don't know if it's modulated somehow, or just overlaid on the input or what.

Trying to get any detailed information has been far more effort than it seems it's worth. I just wanted it because I read it could be used for hypnosis or subliminal messages.

No problem. It was just put together with the information already provided by the other schematic.

There is a short section in The Excalibur Briefing by Tom Bearden that gives a nice description of what the "Method and Apparatus for Simplifying Speech Waveforms" is and does. From what I gather, the essential steps are:

Step 1 - An audio signal is reduced to square waves that retain the periods of the original sound waves, but not all the more specific aspects of that sound. This is done with a "clipper circuit".

Step 2 - This is then fed through a "high band-pass filter". This emphasizes the time differences.

Step 3 - Finally, the signal is transmitted as electrical pulses along the skin by treating the body as part of a "tank circuit". This allows the nerves to receive it.

The last article on the Rex Research page, Another Look at the Neurophone by Rick Andersen, says that while such a simple circuit would indeed work, it would sound tinny as if the person is "speaking through a kazoo". It then goes on to describe a different way of making it that can yield a much higher quality sound. The part entitled Integrate, Compare, Differentiate, and Sum is particularly relevant to this circuit here as they seem quite similar in some ways. It also goes into a few really fascinating explanations of how it relates to the functioning of the cochlea, and its similarity to the functioning of the retina as well!

There is quite a lot of detailed information on the Rex Research page (e.g.: explanations of the different versions of the Neurophone, the history of its discovery, ideas as to how it works physiologically, etc.). It takes a little patience to go through, but it is definitely worth it.

While I'm sure pretty much anything played through such a device would be an interesting experience (hypnotic inductions and subliminal messages included), I think it would be particularly suited for brainwave entrainment and experiments in neurogenesis. It might even be possible to use the device to help repair brain damage and the like. That would be wonderful!

Thank you for starting this topic. I will continue to try to learn more about it.

I remembered back in February when I saw this article in NewScientist that the army had been using transcranial electric stimulation to boost learning (in a hypnosis-like state) by applying ~9 volts of current with the anode on the right temple (possibly the right motor cortex from other things I've read on hypnosis) & the cathode on the left arm. I figured that if this was done with the neurophone, the wearer would more easily remember or be more inclined to act on the message carried through the neurophone.

I sent an email out & was told that a batch of neurophones are being made in Germany that might be on sale for around $800 each. I still think emulating it would be a far better idea, regardless of sound quality.

What a stroke of luck:

Make a DIY Flanagan ‘Neurophone’ with a TL494 « some electronic projects