I have two designs in mind for a spherical speaker:
- (Works only for an infra-sonic speaker) The speaker could be a balloon with an active pressure control that changes the balloon radius according to the signal input to produce spherical wavefronts.
- (Works for audible sound) The diaphragm could be shaped like a football with multiple segments stitched together. The individual segments can be connected to a movable coil, fixed magnet system. If all the coils are in phase this speaker should also produce spherical wavefronts.