A sound
transducer (10) for imparting acoustical energy directly to a
solid surface (12) while achieving the
sound quality and
frequency response found only in conventional diaphragm speakers. The sound
transducer (10) comprises a pair of symmetrical
magnet assemblies (16, 18), a pair of symmetrical voice coils (66, 68), and an
actuator (22). The
magnet assemblies (16, 18) each present an area of concentrated
magnetic flux (60, 62). The symmetrical voice coils (66, 68) are positioned in the vicinity of the areas of concentrated
magnetic flux and are operable to receive an alternating
audio signal which causes the voice coils to move relative to the
magnet assemblies. The
actuator (22) moves with the voice coils and includes a foot (70) for
coupling with a
solid surface to impart movement to the
solid surface and thereby produce sound when the voice coils receive the
audio signal. The
actuator (22) is coupled to the voice coils (66, 68) by an elongated shaft (24). The shaft (24) is supported for linear movement by a pair of spaced-apart bearings (74, 76).