# How close does a meteorite have to be in order to be heard by the human ear?

...speaking of Perseid meteor showers...How close would a Perseid meteorite have to be in order to be heard by the human ear? Is it even possible to hear a Perseid meteorite? If they come close enough, would we hear "ka-boom!", or would it sizzle, or do they always burn up before we hear them?

-
It's impossible to hear a meteor, as there isn't enough matter in space to transmit the sound. A meteorite is a different matter though. –  Ignacio Vazquez-Abrams Aug 13 '12 at 3:50
Its also related to the size of the meteorite. What should be the size of the meteorite that it can reach the ground? (if it is from Perseid meteor shower) –  Asphir Dom Aug 13 '12 at 6:55

There are a few phenomena that can cause sound to be heard from a meteorite. Here it says that sonic booms as well as shock waves due to larger fragments breaking up can reach and be detected by the human ear. There is also the so-called electrophonic effect.

Given that most meteorites burn up at ~100km altitude, sonic boom and shock waves would take

$t \approx \frac{100\mathrm{\ km} }{340 \mathrm{\ m/s}} \approx 5 \mathrm{\ minutes}$

before reaching your ear. Even if the sound is strong enough to be heard after 100km of travel, it'd be hard to associate that sound with a specific meteorite during a shower.

Here it is mentioned that low frequency radio waves emitted by a meteorite burning up can cause the human ear to register sound -- the electrophonic effect. A more detailed explanation can be found here (Sorry I couldn't find a link that works properly describing the effect in relation to meteorites). This sound would be heard instantly upon seeing the meteorite (as radio waves travel at $c$), and resemble a low hissing sound ("like bacon frying").

-
That ~ about is correct. There exist meteorites that reach the surface. I have a witness, a sailor, who 40 years ago in the middle of the ocean heard the bang of a falling meteorite, which they were tracking by eye. –  anna v Aug 13 '12 at 10:53
@annav most burn up, and indeed, some reach the surface. I'd imagine much louder sound would be the result from those type of meteorites -- partly because they can bring their shockwaves closer to the observer, and partly because they are necessarily larger. –  Rody Oldenhuis Aug 13 '12 at 11:44