Panel-form loudspeakers

A panel form loudspeaker comprising:

• a member having selected values of certain physical parameters which enable the member to sustain and propagate input vibrational energy in a predetermined frequency range by a plurality of resonant bending wave modes in at least one operative area extending transversely of thickness such that the frequencies of the resonant bending wave modes along at least two conceptual axes of the operative area are interleaved and spread so that there are substantially minimal clusterings and;
• disparities of spacings of said frequencies, the member when resonating having at least one site at which the number of vibrationally active resonance anti-nodes is relatively high;
• and
• a first transducer and a second transducer mounted on the member, each at a different one of said sites on the member, each of the transducers being capable of vibrating the member in at least a portion of the predetermined frequency range to couple to and excite the resonant bending wave modes in the member and cause the member to resonate and produce an acoustic output.