Why is it that when you sing at the same tone your ear vibrate.?

Question

One day my friend and I were practiceing singining. When we hit the same note both of us had a ringing noise in our ears. My friend and I were wondering why this happened.

Answer 1

is that so?

perhaps you're marvelous singers!

i tried it with my friend, watching the ear intently but no ear vibrated.we just burst out laughing like the idiots we are.. . . lol

Answer 2

"ringing noise"...

I'm guessing that perhaps it was not so much a "ring" like a door bell, but rather a kind of buzzing or vibrating sensation, probably at a slightly different pitch?  And probably you had to hold the note for a few seconds - it didn't happen when  you glided through the notes.  I hear the same thing - often when I am doing scales or vocalizations with a piano.

My theory is:

When you and your friend hit the same note, the sound waves in the air form what is called "constructive interference" in physics - the energy waves of the similar notes actually add to together, and get bigger and stronger.  So the major note, and many secondary or resonance frequencies will be amplified, as well.  So, your ear will be getting constructive feedback - the sound it hears will be louder than what you created, and have stronger secondary harmonics, as well.

And the same note will sound somewhat different in you head than it does in the air - the sound is conducted from your throat and mouth mostly by bones in your jaw and skull to your ear, which is filled with fluid.  Vibrations will sound different in diferent media.  (think about how strange your own voice sounds to you on a tape recorder - even though everyone else says it is an accurate recording...)

The external notes, if held for a couple of seconds, will set up a resonance or standing wave inside the fluid of the ear.  You'll also be getting similar, but slightly different vibrations from the bones in you jaw and skull - they will also set up standing waves or resonance waves.  The "ringing" is the combination of the standing waves set up by stronger than normal external sound and it's harmonics, plus the internal sound.  The combination is going to be slightly different from either the external or the internal sound by itself - so it sounds like not exactly the note itself, but a "ringing" which is kind of like it.

In order for this happen, we need to have an external source hitting the same note, and have the note held for a couple of seconds so the standing waves can develop and start resonating in our ear.  If we glide through the notes, the standing waves and resonance don't have time to develop.