Abstract: Many transducers suffer from the problem that the way they behave in response to actuating signals of different frequencies, and particularly their directional properties, or beamwidth, depends on their physical size and shape. What is required is a transducer which changes its effective size as a function of frequency, and the present invention proposes such a transducer in which the transducer element (11, 12, 13)--the active part of the transducer, such as the diaphragm in a loudspeaker--permits automatic frequency-sensitive control of the beamwidth by providing frequency-dependent "shading" of the local response to the signal across the face of the element, using a resistive coating (11) in association with a capacitive layer (12, through which the currents representing that signal travel) such that the CR value of the combination varies over the surface of the element.