I am trying to understand how my iPhone can continually listening for me saying
Hey Cortana or
Okay Google without quickly draining my battery down.
I imagined two kind of algorithm. One that record slice of time such as 10 ms wide slices each 200 ms and perform a synchronous detection on specific frequencies. However these parameters strongly depend on the characteristic of my voice. Moreover, it will still consume a lot of CPU power to continually try to match a
Hey Siri in the middle of nowhere.
What kind of efficient low-power algorithm/implementation (hardware or software) can perform such task?
This is somehow related to this patent I think: https://www.google.com/patents/US20160253997
I read some articles that talk about hidden Markov models, but I doubt it is very low power approach.