Is the soundpressure, which is created by air movement, the same as if it is created by sounds? If you use a microphone with a pop filter and without a pop filter and you blow into it, than there is a huge difference in soundpressure, but is this really soundpressure like from a noise? For example: Noise is a longitudinal airwave, which deflects the microphone membrane and is than registered by the microphone. But if I blow air onto that membrane it is only deflected in one direction as long as the wind blow goes and it does not create a „sound“. Can this wind even create a soundpressure? Can you damage a microphone membrane by just blowing air into it. How much sound pressure can a air blow create? Scuba divers regulary perform a valsalva maneuver. They equalize pressure in the middle ear by pressing air into it. This leads to a deflection of the tympanic membrane, but it does not sound very loud. Why? I thought if blowing wind onto it, there will be a huge soundpressure, like on a microphone without a pop filter. Can you explain it to me? I‘m new in acoustics.
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When you blow on a microphone, the air flow is not perfectly smooth. There are many little swirls and such. These vibrate the microphone membrane, and the vibration is sound. If you smoothly and uniformly increase air pressure over the whole microphone, you will smoothly press on the membrane and create no sound.
In your ear, pressure waves are converted into mechanical vibrations. The vibrations stimulate nerves, and you hear a sound. If you smoothly increase pressure, there are no vibrations and no sensation of sound.
Sound takes very little motion of your ear drum. The loudest sound I ever heard was a very small ant that walked into my ear and across my eardrum.
answered Sep 2, 2018 at 0:16
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$\begingroup$ Very nice answer. Thank you a lot. But I still have one question. Your example with the little ant is very apt. But why is pressure equalization (eg. while scuba diving) not that loud? I thought it should be loud, because if you perform a valsalva maneuver, than the air is pressed into the middle ear and than blocked by the eardrum. This airstream creates also vibrations on the tissues in the middle ear. Here is a link about the valsalva maneuver: en.m.wikipedia.org/wiki/Valsalva_maneuver $\endgroup$– J. ScottCommented Sep 2, 2018 at 12:25
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$\begingroup$ I don't know. Bats "shout" really loudly and then immediately listen for a very faint echo. To keep from being temporarily deafened, they have a mechanism to "disconnect" their ears as they shout. scientificamerican.com/article/how-do-bats-echolocate-an But I doubt this is happening in people. $\endgroup$ Commented Sep 3, 2018 at 1:03