Page "Loudspeaker" Paragraph 34

Bending wave transducers use a diaphragm that is intentionally flexible.

The rigidity of the material increases from the center to the outside.

Short wavelengths radiate primarily from the inner area, while longer waves reach the edge of the speaker.

To prevent reflections from the outside back into the center, long waves are absorbed by a surrounding damper.

Such transducers can cover a wide frequency range ( 80 Hz to 35, 000 Hz ) and have been promoted as being close to an ideal point sound source.

This uncommon approach is being taken by only a very few manufacturers, in very different arrangements.