A transducer comprising: a flat strip of metal formed into a closed metal loop with two substantially parallel sides and rounded corners, a solenoid fixed to a surface on a first parallel side, and fixed magnets attached to an opposite parallel side of the trapezoidal shape to bring the fixed magnets into proximity with the solenoid, wherein at least one lateral side of the trapezoidal shape coupling said parallel sides has a continuously varying width, resulting in the transducer being able to resonate with high fidelity over a range of frequencies in response to reception of a signal comprising varying frequencies.