On-device speech-to-text for VAHA: the model, where transcription happens, and a first accuracy test

Summary

Describes VAHA's speech-to-text stage and checks the current build against the product README. The device transcribes its own captures on the device with faster-whisper base.en by default; the README's model table says small (277M, "fine-tuned") while its pipeline description says base.en. Notes recorded on the phone are transcribed on the device when the app is connected, sent to Groq when it is not and a key is set, and lose their recording when it is not and no key is set; with a key set, note text also goes to Groq for titles. A first test on 12 synthetic sentences (120 words) on a development computer found 3 word errors for base.en and 2 for small, one misheard word apart, with small about 2.9 times slower. TRL 3; the path to TRL 4 is limits for accuracy and speed, a corrected README, phone recordings kept until transcribed, and the test repeated on the UNO Q with real speech.

Key findings

• Model. The device runs base.en by default; the README's model table says small (277M), and its pipeline description says base.en.
• Where it runs. Device captures never leave the device for transcription. Phone-recorded notes can be sent to Groq, and with a Groq key set, note text goes to Groq for titles.
• Lost recordings. A phone-recorded note's audio is deleted after every transcription attempt, including when no transcript was made.
• Accuracy and speed. One word separates the two models on a 120-word synthetic test; small took about 2.9 times as long. Not yet measured on the UNO Q or with real speech.