The brain tissue cannot feel/hear any vibration of its own. It will be out of phase to some degree (air transmitted sound pressure VS bone tranmitted) no matter how large or small a person's head.Īgain, forget the brain tissue and vibration. The size of a person's head will have nothing to do with it. I'll stick with my hypothesis until someone tries the earplugs to disprove it. The only path the sound has other than the path through the bone with the tuning fork is in through the external ear. The tuning fork is external, so therefore only the sound transmitted into the bone is going to be of great enough amplitude to consider. With a folk singer, the sound is being generated internally within the singer. This is why folk singers sometimes sing with their finger in one ear.Īnd inplug in one ear won't increase the sound level in the ear canal in this case. Placing earplugs in one/both ears should lead to an increase in perceived volume as this prevents sound loss from the open ear canal.

Placing tuning forks against the skull are the basis of the Rinne and Weber tests of hearing. Therefore, differences in perceived volume should be due to transmission through the CSF. Evidence suggests that vibrations transmitted more efficiently by the bones of the skull would be perceived at similar volume regardless of the position of the tuning fork. I think the sound is being transferred to the middle or inner ear via the cerebrospinal fluild (CSF) and the tissues of the brain itself. However, if the effect is heard by people with different sized heads, or with different tuning forks on the same head, it makes me sceptical of this explanation.Īfter thinking for a while, I agree with twaaang. I initially thought this may be due to differences in phase, as Smyers suggested. #If not, then I'm talking out my rear and someone else will have to figure it out. #If the loudness level is now perceived as being louder in the ear that the tuning fork is nearer to or about the same loudness in both, then my hypothesis is correct and we have a bona-fide theory. #Then do the same experiement you did before. #It too is somewhat out of phase, but because the loudness is less through the air due to the distance being greater, the amount that it can cancel it out is much less, so it is perceived as being louder in the more distant ear.Īn interesting experiement to prove this out would be to get some of those foam earplugs, put them in your ears and let them fully expand for 5 minutes. #The other ear that is farther away from the tuning fork receives the sound through the air at a distance at least twice as far away, this means the loudness is at least one-forth as loud (inverse square law). #The results is one cancels out the other partially and is perceived as being softer. #Also, it is bound to be out of phase (although not perfectly 180 degrees) with the sound through the bone. #However, the ear that the tuning fork is nearest is so close that the sound through the air is fairly close in loudness as that through the bone. #So the same wave that reaches the inside of your ear via the bone gets there first, as well as louder. #Solids such as your skull transmit sound better, faster and with less loss, than the air. #The sound is travelling through your skull, as well as through the air. #The tuning fork is closer to one ear than the other. It's sort of the same thing if my hypothesis is correct that this effect is being caused by phase cancellation in your head. #Phase cancellation occurs every day all the time in sounds your hear, you just either don't notice because it is subtle, or really don't know what it is your are hearing. #So what you hear is a lot softer (and weird sometimes) when one is hooked up backward. #Ever hook up the wires backward on one of your stereo loudspeakers and then hook them up correctly and listen to the difference? #When they are backward, you put one loudspeaker out of phase perfectly 180 degrees out from the other. What is most likely in my mind is a phase cancellation issues. #So the brain itself vibrating isn't perceived at all, as it has no perception of its own and relys solely on external stimulus. #So in the case of the ears, it gets its only input from the ears for hearing. #It must receive all its input from the nerves. #Remember, the brain itself can't hear anything. Let me rule one thing out - From my understaning of physiology It's definitely nothing to do with left brain nerves to the right of the body.

#So I'll waste 10 minutes writing about this. #I'm no physiologist, but I am an acoustic engineer. Phys.I love this kind of stuff and will take a whack at it. (Cambridge University Press, Cambridge, 1985)

Tuning fork low frequency