On May 10, 2009, at 2:48 PM, Escapement wrote: > My understanding of a transducer has always been that it is a device > that > takes one form of information or energy and converts it into another > form. > (Like the speaker example given where *electrical current* is > converted to > physical vibrations through the electromagnetic voice coil). The > speaker > isn't a transducer because the voice coil vibrates the membrane - > it's a > transducer because it takes the *electrical current* in the wire and > converts it to vibrations *(sound)*. In the same way that a > microphone is a > transducer because it takes *sound* and converts it to an *electrical > signal*. > > But with the soundboard I don't see this conversion. After thinking it over, I agree with you on this. A classic series of transducers would be a coal fire (heat energy) heating water to make steam that is directed at a turbine, causing it to spin (mechanical energy), which, by means of magnetic field and copper coils makes electric current (electrical energy), which, directed through the filament of a light bulb makes light energy (and heat energy). All are real conversions to obviously different forms of energy. With a piano, though, we have the mechanical energy of a finger moving a key, which causes a hammer to hit a string and sets it to vibrate. Mechanical energy converted to mechanical energy in a different form via the action of intermediary mechanical devices. The string is coupled to a soundboard, and energy is transferred causing the soundboard to vibrate, again a mechanical transfer to a mechanical form of energy. The soundboard, having a large surface area, and operating in atmosphere, transfers some of its vibrational energy to air particles, which oscillate creating waves. This still seems like mechanical energy to me. The air oscillations reach an ear drum, setting it vibrating. IOW, a whole series of transfers of mechanical movement from one device or medium to another. Not being versed in physics, I don't know whether there is a difference I am missing, but it seems much more like a continuum than any two steps in the example above. I wonder also about referring to sound as energy. It takes energy to make sound happen, so sound can be said to be a manifestation of energy. But is sound a "form of energy?" Maybe this is too abstruse to worry about, but some of the confusion in this discussion seems to come from assumptions like the notion that sound is equivalent to energy, and similar analogies that maybe aren't actually valid. Regards, Fred Sturm University of New Mexico fssturm at unm.edu
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