There are some open source libraries that make this relatively easy:
- https://github.com/Kitt-AI/snowboy (looks to be shutdown now) - https://github.com/cmusphinx/pocketsphinx
This avoids having to stream audio 24x7 to a cloud model which would be super expensive. This being said, I'm pretty sure what the Alexa does, for example, is send any positive wake word to a cloud model (that is bigger and more accurate) to verify the prediction of the local wake word detection model AFAIK.
Once you are positive you have a positive wake word detected - that's when you start streaming to an accurate cloud based transcription model like Assembly to minimize costs!
Here's an example repo that might be interesting (from initial impressions, though there are many more out there) : https://github.com/vineeths96/Spoken-Keyword-Spotting
uMusic patent: https://patents.google.com/patent/CN1637743A/en
Further reading: http://products.bose.com/pdf/customer_service/owners/uMusic_...
The best do it yourself instructions are in a book called Tiny ML.
Compared to super deep transformers, you'll find that deployed WW detectors are as simple as SVMs or 2 layer NNs.
It'd be cool if there was the ability to train a phrase locally on your own premises and then use that to begin the real transcription.
This probably wouldn't be super difficult to build, but was wondering if it was available (didn't see anything at a glance)