compression waves

[Ron Nossaman]

>>What i did say is that I believe  [!!] bridges are transparent to
longitudinal
>>modes.........highly unlikely that any external clamping mechanism 
>>will be able to prevent the internal wave transmission past it, as 
>>long as the molecular structure is continuous. Transmission waves 
>>simply pass right past these clamped bits. They will eventually be 
>>reflected when they reach the geometric and physical _end_ of the 
>>bar, or localized discontinuities.
>
>This contradicts Conklin's finding (which I have verified) that the 
>frequency of the wave is a function of the speaking length.  As I 
>mentioned yesterday, the propping up of the speaking length with a 
>_simple_ bridge, by which I mean the equivalent of a low violin 
>bridge, is of course adequate to change the base frequency of the 
>transverse waves but will not affect that of the compression wave. 
>By contrast, anything in the nature of a firm clamp, which includes 
>the clamping effect of a piano bridge, does serve as a termination 
>(broadly speaking) of the wire with respect also to the main 
>compression wave.  I say nothing of its harmonics, since I haven't 
>tested these.

This is very similar to the results I just got with a quick and dirty
monochord. A round, unanchored "bridge" didn't much affect LM1, but a
solidly anchored pinned bridge, like one found in an actual "modern" piano,
produces an LM1 dependant on the speaking length. A piano like bridge
doesn't, by my observation, seem to be transparent to LM.

Ron N