1) SPL measured at the mic is basically a reading of pressure variation in the air, which is due to molecular motion on not one, but two sides of the microphone.
Since in my first musings I discussed molecules interacting on the front of the microphone diaphragm, what about the restorative force coming from the OTHER side of the microphone that allows measurement of complete wave modulation?
If the restorative force is limited to approximately atmospheric pressure, the restorative force on the microphone would be ~14 PSI with a perfect vacuum on the other side.
14 PSI corresponds to a pressure variation of approximately 190db, therefore, our measurement capability is limited to a little over this unless other factors are brought into play.
So, basically we are trying to do two very simple things to the microphone, right?
The first is exert as close to infinite force as possible on side 1 of the diaphragm. The second is to then exert as close to zero force as possible on side 1 of the diaphragm.
Doing this will yield our theoretical peak variation in pressure and allow the aforementioned ~190db measurement, right?
See rarefaction question.
If we stimulate maximum air velocity towards the microphone, don't we then engender molecular momentum in one direction, allowing for that very low pressure area over the microphone?
Think of the microphone diaphragm as curved. When we exert our pressure phase of limited duration, we push the curved diaphragm down. As we do this, molecules flow over the diaphragm much like water would, and flow off to the sides. As we exhaust our pressure phase, we end up with the rarefaction phase right in front of the microphone, because air molecules were displaced perpendicular to wave motion by the curved microphone. If the rarefaction phase exists in front of the microphone, some portion of the restorative pressure on the microphone can take advantage of this to restore the microphone.
But, what portion? If the rarefaction phase is a portion of a spherical surface, there can be a flow from only those portions perpendicular to this rarefaction field, which means from the microphone or from previously transmitting molecules in the wave, right?
(I don't know who's gonna see this leap..i'm not sure if I have it fully constructed yet )
So, could we assign a frequency to the speed at which these two high pressure area's flow into this low pressure area in relation to the wave frequency?
hmmmmmm
ShadowStar
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I've actually read that.. RC didn't make much sense on that one, I must say.. Contradicted himself a few times.
ShadowStar
RC and Brad Eubank, who I know, seem to have their greatest impasse concerning exactly how the meter reads SPL related to amplitude vs frequency.. If that was definitively answered, one or the other would have been at least the momentary winner of that debate..
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