this is exciting! it's still at prototype stage: 'getting about 90% accuracy [distinguishing between the spoken digits 'zero' to 'nine',] with the code as it stands.'<p>i wonder if modern continuous optimization algorithms could yield a neural network that would do better than this mfcc approach at, perhaps, even lower computational cost<p>they seem to have gotten more expensive lately, though (11.83¢ in quantity 500), and lcsc is out of stock on the ch32v003. they only have in stock ch32v203 and up, which costs 37.5¢. <a href="https://www.lcsc.com/products/Microcontroller-Units-MCUs-MPUs-SOCs_11329.html?keyword=ch32v" rel="nofollow">https://www.lcsc.com/products/Microcontroller-Units-MCUs-MPU...</a><p>digi-key, as usual, doesn't list the part at all