I get what your saying Lord... it works on a very similar idea (infact maybe the same), as this:

F = BIl sin è
(F=force, B= flux density, I= currnet, è= angle of currnet in relation to flux lines, l= lenght of conductor) ,which can be re-arranger to give:
I = F/ Blsinè....
So basically, the more force, and more prependicular (as sin 90 = 1) the louder the signal...I understand!