"remember too that sound travels as well through springy floors (and walls)"
Absolutely, but my point is once the sound wave strikes/energizes a solid surface/object, the transmission then becomes mechanical, no longer acoustical. I consider acoustical to mean through the air.
In this view, sound waves do not pass through walls and windows directly. Coming from their source they strike a solid surface (drywall or glass in this case) where the energy is transferred by mechanical means. Some level of sound is reflected back, while some frequencies are filtered out (dissipated) in this process which is why higher pitched sounds may not survive. That transferred mechanical energy which survives then excites (vibrates) the air on the other side of the wall or window where it becomes acoustic again.
Consider the transformations with your violin. You pull the bow across a string which creates a mechanical resonance. If someone stands close enough to you they may hear the acoustic transmission of that string vibration, although it will be at a very low level. But the string vibrates the bridge as well as the air, which transmits energy to the soundboard (top of your instrument), which then vibrates air within the cavity of your instrument which becomes amplified by resonant reinforcement and comes out the f holes as acoustic sound waves which can now be heard from a much greater distance. (And yes, some acoustic sound is also projected out from the soundboard itself.) All this involves two different types of energy transfer.
I'm not trying to split hairs here and I don't pretend to understand this as well as a trained engineer or physicist. But I do believe if we are to address a problem it serves us to understand the causes as best as we can. This is why I break down vibration issues for turntables into three separate sources - acoustic, internal mechanical, and external mechanical.
Absolutely, but my point is once the sound wave strikes/energizes a solid surface/object, the transmission then becomes mechanical, no longer acoustical. I consider acoustical to mean through the air.
In this view, sound waves do not pass through walls and windows directly. Coming from their source they strike a solid surface (drywall or glass in this case) where the energy is transferred by mechanical means. Some level of sound is reflected back, while some frequencies are filtered out (dissipated) in this process which is why higher pitched sounds may not survive. That transferred mechanical energy which survives then excites (vibrates) the air on the other side of the wall or window where it becomes acoustic again.
Consider the transformations with your violin. You pull the bow across a string which creates a mechanical resonance. If someone stands close enough to you they may hear the acoustic transmission of that string vibration, although it will be at a very low level. But the string vibrates the bridge as well as the air, which transmits energy to the soundboard (top of your instrument), which then vibrates air within the cavity of your instrument which becomes amplified by resonant reinforcement and comes out the f holes as acoustic sound waves which can now be heard from a much greater distance. (And yes, some acoustic sound is also projected out from the soundboard itself.) All this involves two different types of energy transfer.
I'm not trying to split hairs here and I don't pretend to understand this as well as a trained engineer or physicist. But I do believe if we are to address a problem it serves us to understand the causes as best as we can. This is why I break down vibration issues for turntables into three separate sources - acoustic, internal mechanical, and external mechanical.