Why is it that certain frequencies make your eardrums beat?

Does anyone else get that thing where certain frequencies of sound will make your eardrums beat or flutter? What is that?

Are you talking about certain frequencies alone or are you talking about combinations of frequencies?

If you mix two sine waves together that are relatively close in frequency, you will perceive them to be “beating” together to form a third frequency. For example, if you mix a 100 Hz wave with a 105 Hz wave, you’ll hear a 5 Hz “beat”, which will sound like a flutter.

Heterodyne radio receivers work on the same basic principle, except with radio waves instead of audio frequencies.

Beating and fluttering from single frequencies can be caused by physical problems with your ears, such as certain forms of tinnitus, mucus or blockages in your Eustachian tubes, problems with your eardrums, etc.

Sorry to respond so late – had a very busy day. I’ll try to describe it the best I can. I thought maybe it was something more common that others would recognize.

The first time I remember feeling it was when my mother would vigorously scrape out a pan with a metal spoon. (This would be decades ago.) I believe sometimes water running in a stainless steel sink will do it too. I can’t seem to recall many other specific instances of it even though it has always happened to me sporadically, except for today, which is why I posted. I got a sudden urge to hear “Isn’t It a Pity,” a George Harrison song, and was pleased to find a remastered version. To my amazement, it happened all the way through the song.

I used to sing in choir, and I know the phenomenon you mention, where two very close notes will appear to “beat” together. That’s an artifact of the waveforms generated, and it happens externally. You hear a phasing sound – but you hear it normally.

What I am talking about is an actual physical sensation inside my ear. If it isn’t my eardrum, it’s one of the tiny inner ear bones, because I can feel actual motion or vibration inside. It’s not painful but it is uncomfortable. Today was the first time it happened other than (mostly) momentarily. It doesn’t seem to be associated with loudness; it’s just certain sounds. (almost certainly not single frequencies) If it makes any difference, I have pretty acute hearing.

I don’t know if that’s what the OP means, but I hear a beating noise when I open only one window (on the driver’s side, say) in a fast-moving car. Once I open a window on the opposite side, even if only a little, it goes away. Anecdotally, this seems to affect some people more than others. My mother and I are very sensitive to it, while my father and my wife hardly seem to notice.

That one would be the Helmholtz effect. Some people will notice it more than others, but it makes a big difference where you are in the car in relation to the open window(s).

Occasionally I get an effect when listening to voice or some music, normally in my left ear when I have the audio piped into my right ear (holding a phone up to my right ear, for instance). The left ear will have a physical pulsing sensation, a bit like a muscle spasm approximately in sync with the syllables or the music’s beat. Is this similar to what you’re experiencing?

Yes, exactly! Very interesting, thank you.

You might be experiencing “tympanic flutter”. It’s an abnormal version of the “tympanic reflex”, which is a reflex where little muscles in your ear tighten your eardrum. It happens normally to protect your hearing and equalize loud noises: your own swallowing or speaking, or loud external noises. However, some people become sensitive to sound (often in particular frequencies) so that this reflex is triggered abnormally. More here, from a site about more severe hyperacusis.

I have this in one ear in mid-upper frequency ranges. When I play music I can wear an earplug, but unfortunately it also triggers when lots of people are talking so social gatherings can be irritating.

I get the impression that the OP is describing something like this (because of the part about the metal pan) rather than the sensation of low-frequency flutter, which I think is more like a tactile perception of sound pressure changes - that is, being sensed by something other than the eardrums and associated equipment.

I get the tympanic reflex thing with jingling coins, but only when I’m tired, for some reason.