So would u suggest a sine wave of rhe harmknic or maybe just playing the sound of actual recorded cat purr on speaker into back of neck?
I am not sure what would be better, a recorded cat's purr or a 120 Hz sine wave.
A couple of weeks ago I tried passing a 120 Hz sine wave (created by a tone generator app on my computer) through a HiFi amplifier and into a HiFi loudspeaker, and turning the volume to a reasonable level. After just a few minutes, I found the sound quite annoying, and it also made my ears go a bit funny. So that experiment was quickly terminated.
So then I started thinking in terms of trying to create a 120 Hz mechanical vibration directly in the body tissues. The first idea that came to mind was women's sexual vibrators; I wondered if any might have a vibration frequency around 120 Hz.
Intriguingly, I came across
this article on the use of a 120 Hz vibrator applied to the throat to improve the voice quality and vocal range of singers. Unfortunately the vibrator used in that article (the Lelo SIRI) is quite expensive, at £130.
After a bit more Googling, I came across a much cheaper and probably better solution:
audio exciters. I'd never heard of these before, but basically they are gadgets that you glue or screw onto a surface such as a table, cupboard, etc, and they turn that surface into a loudspeaker. I was looking at
this 30 watt audio exciter made by Monacor which costs just £15.
I've not bought this item yet, but I imagine that if you placed this exciter directly in contact with your neck, it would transfer the vibrations into the neck tissues quite efficiently. As with a regular loudspeaker, an audio exciter needs to be driven by a HiFi amplifier.
I think this experiment though would not be without risk. It might somehow make the ligaments worse, and/or the vibrations might not be good for the brain.
This study looked at the effects of vibrations that people receive from traveling in motor vehicles, and found that there was a cumulative ill effect on the brain.