Speaker Driver Material & The Sound of Dissimilar Materials

I'm sorry but "soundwaves"are not what we hear,soundwaves are nothing more than the pressure waves of air movement caused by the vibration of initiating object.If all we heard where soundwaves everything would have the same tone.It is the frequencies of vibration that gives us pitch,timbre(tone)& texture.This is where my confusion lies.Just can't seem to wrap my brain around how an aluminum or poly woofer can accurately vibrate at the same freq.as the wooden body of a cello(for example) & this is what I'm hoping someone can explain.
 Thanks for the reply though...