A new thin speaker.

The BBC website has announced a new ultra-thin speaker consisting of several thin laminations. This idea reminds me of a science fiction short story I wrote back in the 70s. Where I suggested that speakers would be built which worked on the same principle as a thin film capacitor but spread out flat and glued to the wall just like ordinary wallpaper.

With more recent discoveries I was assuming that a sound emitting diode would be invented. The idea in both cases is to provide much larger driver area to move the required volume of air. As driver area increases so excursion drops for the same output at the same frequency. As frequency drops so must excursion increase dramatically. A limit is reached around 10Hz beyond which it becomes very difficult to effectively couple conventional drivers to the air. An impedance mismatch makes ULFs very difficult to reproduce with any degree of efficiency.

The Thigpen rotary 'fan' subwoofer was a brilliant attempt to overcome the difficulties of reproducing anything below 10Hz. It has not achieved widespread adpoption for a number of reasons. Its very high installed price is one of the most obvious problems. Though unwanted noise seems to be an issue requiring heavy damping in a plenum before exposure of its output to the listening room itself. I am surprised that no attempt has been made to provide a cowl to direct the air without turbulence through the panel aperture surrounding the fan itself.

It may be that this new ultra-thin speaker will be just as incapable of reproducing deep bass as the previous NXT panels. Perhaps it is as well that most of us have no capacity for reproducing sub-10Hz frequencies anyway. ULF infrasonics carry well and might cause all sorts of problems for neighbours.

Flat-Panel Stereo Speakers - Popular Mechanics

The new speaker claims a good spread of sound and lack of point source but the wording of the BBC article is extremely confusing. I am not aware of having been "blasted" at any time in my long audio journey. Not even by early horn tweeters.

BBC NEWS | Technology | Thin speaker offers 'crisp sound'