You're not going mad
Written and dispatched to silicon.com from the marina at Gocek in Turkey via a free wi-fi service
About an hour ago a lady from Belgium emailed me saying she was worried about the fact she keeps hearing Morse Code in her head without the aid of any radio receiver or other form of electronics.
Scanning the internet I found a large number of pages giving 'hocus pocus and pseudo-scientific mumbo-jumbo' explanations - and worse, a lot of paranoia from those worried about everything including their own shadow.
So I decided I'd better try and put the record straight. Here is my email reply to the lady:
No need to worry about this as it is a common occurrence and fully understood and explainable. Earwax and moisture on the outside of the ear, and electrolytes in the inner ear are ideal mechanisms for creating a 'rectifying or electro-mechanical action'. This means that the energy from a nearby radio transmitter gets converted into an electrical and/or mechanical signal in your ear. Any mechanical flexing of wax or rectification by the electrolytes will do the trick! And any direct conversion to an electrical current in the acoustic nerves, and ditto, you will hear it.
Another likely mechanism is the electrical signal to mechanical vibration conversion due to metal-based fillings in teeth and the associated moisture and acidity in the mouth. Sound propagation would then go via the jawbone to the ear.
The chemistry is a bit complex as is the electrical/mechanical conversion and can include several signals at once 'heterodyning or interfering' to give you a clear tone. But it is explainable - and you are not going mad. And I sometimes hear similar transmissions too!
Who is the culprit for the transmission? Not many people use Morse Code anymore but radio beacons, embassies and some news agencies do. So listen to the signal and see if it repeats regularly: If yes - then it is undoubtedly some form of beacon. If the Morse code is slow and deliberate it is most likely a human operator. If the Morse is incredibly fast it is most likely a machine. In either case it may be an embassy, the military, a news feed by an agency etc.
One of the last vestiges of a Morse generation is the amateur radio community. Just have a look around your community for unusual antennas on houses and buildings and see what you can find.
I hope this helps you.
P.S. There are a lot of bogus/misleading websites on this topic that purport to be authoritative but in reality they add nothing to the understanding short of witchcraft and paranoid thinking!
Searching through my writings in the early 1990s I found this rather more succinct explanation:
"We are largely made up of water, electrolytes, salts and sugars, which is an ideal soup for electrical rectification. Or to put it another way, our ears can look like a cats-whisker crystal set. The only problem with this phenomenon is its unreliability; you can never predict when it's going to work, and sometimes it really is an unwanted distraction."
It is interesting that we increasingly live with and rely upon our technology for our survival, and yet the web is full of superstition and unfounded explanations of what we have fully comprehended for decades. During my search I found all manner of discussion groups making a big and mysterious deal about cross-channel interference in analogue TV and radio systems.
The really worrying thing is that the people responsible seem to have lost the ability to search out the truth and would sooner perpetuate errors of understanding, half-truths and what amounts to worse than 'old wives tales'! Even more worrying: our education systems now seem to be almost encouraging this kind of nonsense.
As the number of people in society with deep technical knowledge (of anything) shrinks we may be left with more and more of this stuff dissipating human effort and resources, and goodness knows we can ill-afford such waste!