https://audioxpress.com/article/the-impact-of-mems-speakers-in-audio
I am still of the opinion that despite the fact that there are other devices out there that are likely to prove to be competitors, these all seem to be some variant on the idea of making a membrane or other active element move air in an analog manner. They are still classical speakers, and still have all the problems that are inherent to analog speakers in an increasingly digital world. Only AP has DSR, and only DSR overcomes these limitations in a practical way for real digital devices. Mike Klasco, the author of this article, was one of the big name speaker experts who acknowledged this several years ago. He has not discussed this here at all, even though he basically said "proof of concept continues to progress", which could easily be taken as "watch this space".
"... This modular paradigm is comparable to “parametric speakers” such as
phased arrays or
using more transducers for increasing the dynamic range. Audio Pixels’ Digital Sound Reconstruction (DSR) technique is based on a theory introduced by Bell Labs in the 1930s. Originally a secure “digital” speech vocoder for military communications with a “digital speaker” to reconstruct the speech.
The sound wave is generated from the summation of discrete pulses that are produced from an array of pressure generating micro-transducers. Within each transducer is an array of identical elements fine-tuned to a particular frequency. As with analog speakers, different frequencies are produced by varying the timing of the motion. Proof-of-concept continues to progress. Audio Pixels is in partnership with Sony as one of its MEMS foundry partners and ICsense for the ASIC design. ..."
However I think his description is not actually very clear, and may even be misleadingly wrong.
"... array of identical elements fine-tuned to
a particular frequency ...
different frequencies are produced by varying the timing of the motion. ..."
The pixels are not "fine-tuned to a particular frequency", they
all always operate (switch) at a single ultrasonic timing frequency that is much higher than human hearing. This frequency is basically a clock-tick timing signal that times the turning on and off of the pixel. Yes, the sound is reconstructed by adding multiple pulses in a timed sequence of ticks that produces the progressive displacement of air that becomes the analog sound wave, and more are added or reversed over time depending on the wavelength and the amplitude of the emerging sound wave. The timing of the pixels actuations are not varied, rather, differing numbers of pixels are turned on or off as required like a Mexican wave that is coordinated by the clock-tick timing frequency. What this does is to permit all of the pixels to act
together as a
composite speaker membrane,
a virtual membrane. The larger the array of chips included in the "virtual membrane" the larger the number of pixels available, the louder the sound that can be produced, and the greater the range of frequencies that can be reproduced. And all of this is digital so there is no fancy D2A conversions or amplifiers or clever material engineering required to make the sound "sweet". Moreover, it is all simple, effective, and cheap!
So we are all currently drumming our fingers as we wait for news that AP's fabrication adjustments have perfected the current "work in progress on the proof of concept!" Hopefully not long to wait now, but realistically still several weeks before we hear anything definitive. AP may or may not tell us when they actually receive the wafers - early or late. I think (and have requested) they should at least announce that if nothing else, just so nobody freaks out and starts dumping shares again because the "deadline" of early Feb has passed without notice.
(20min delay)