Today we release Whistle, a speech recognition model for mobiles, wearables, robots, smart home, automotive and microcontrollers. It is one 16.9 MB file, runs on the CPU with no dependencies, and loads into the same C++ engine as Needle, from the same container and the same quantisation.
The front end. 16 kHz mono audio is framed at a 25 ms window and a 10 ms hop into 80 log-mel bins, band-limited to 250-3500 Hz and normalised per channel. Thirty seconds is 3,000 frames. A convolutional stem of 128 channels and kernel 9 halves that count three times, leaving 375 frames at one per 80 ms. Every stage after this runs at that rate, and embed returns one row per frame.
The encoder. Eight Simple Attention blocks: four mHC residual lanes and a Monarch Hadamard MLP in place of the feed-forward network, the same blocks Needle uses. The attention is not causal. A frame at 3 s attends to a frame at 12 s.
