# Oído

Oído runs open-vocabulary English speech recognition entirely on a $5 ESP32-S3, a chip with no neural accelerator. Such microcontrollers previously managed only keyword spotting or a fixed command list, while a 13M-parameter Conformer-CTC occupies 14.0 MB at int8, too large for the 512 KB of on-chip SRAM and only partly placeable in PSRAM. The engine schedules execution around flash and PSRAM bandwidth, reaching 3.70%/8.23% word error rate on LibriSpeech test-clean/test-other, within 0.12 points of full precision and 1.8–2.8 fewer errors than the vendor recognizer on the same chip; measured on a board it runs at 1.97 times the audio duration on one core, not yet real time.

Oído runs open-vocabulary English speech recognition entirely on a $5 ESP32-S3, a chip with no neural accelerator. Such microcontrollers previously managed only keyword spotting or a fixed command list, while a 13M-parameter Conformer-CTC occupies 14.0 MB at int8, too large for the 512 KB of on-chip SRAM and only partly placeable in PSRAM. The engine schedules execution around flash and PSRAM bandwidth, reaching 3.70%/8.23% word error rate on LibriSpeech test-clean/test-other, within 0.12 points of full precision and 1.8–2.8 fewer errors than the vendor recognizer on the same chip; measured on a board it runs at 1.97 times the audio duration on one core, not yet real time.