>Ron I need (please :) )your comments on this to clarify where I think you stand >on this point. > >My understanding is that when the strings transverse wave hits the bridge... it >creates a wave front that moves out in all directions of the sound board >assembly, and it has to do so through the whole thickness of the panel. Is >this >correct in your view ? (Speed in any given direction is dependant on stiffness >in that direction ?... yes ? no ?) > >-- >Richard Brekne The physical mass of the string oscillating beyond the line between the speaking length terminations physically displaces the bridge. The string tension variations from the string oscillations rock the bridge also. This is direct physical movement from applied force. Compression waves will also pass through the bridge material, as will transverse waves and progressive transverse waves along it's length. The bridge movement physically displaces the soundboard in a pistonic motion, and with a torquing from the rocking motion. All sorts of things then happen in the soundboard, from diaphragm action to big S curves, to radiating ripples of the entire medium, to internal compression waves, to any other kind of wave form you might like to imagine. These wave forms will obey the natural laws said to govern them by any number of technical books or any other reliable source. If the laws say the waves will travel faster in the direction that is stiffer, that's what I would expect them to do. All sorts of incredibly complex interactions of all this movement occur in reflection, absorption, augmentation and cancellation. Air is displaced by this physical movement of the board (not just the surface) and sound is heard. The soundboard movement moves the bridge, which moves all of the strings which serve as the energy reservoir that keeps the cycle going until the initial energy is dissipated in the work of moving mass and as heat from internal friction losses. The movement of the bridge by the string is not a wave function. It is a mass applied force action/reaction. The string moves the bridge. The bridge moves the soundboard. That is the principal driver of the system. Ron N
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