Apple explains how neural networks work for ‘Hey Siri’ command

Apple has published an article explaining how the “Hey Siri” command works, which iOS users can use to activate the digital assistant without touching a button. This shows, among other things, that iOS devices use two separate checks.

Initially, the coprocessor on the soc, which Apple gives names like M8, M9 and M10, checks with a small neural network how likely the microphone has picked up the command “Hey Siri,” the paper in Apple’s paper says. own online publication on machine learning. That neural network has layers of 32 units. If the probability is low that the phone caught ‘Hey Siri’ then nothing will happen. If the user may have yelled “Hey Siri” and the phone isn’t sure, the software listens carefully for a few seconds.

If the microphone probably did pick up “Hey Siri,” then the coprocessor wakes up CPU cores to push the audio through a larger neural network with 192 units per layer. If it also reveals that the user has yelled “Hey Siri,” the audio continues to the server, where the speech recognition system checks to make sure the user hasn’t accidentally said something like “Hey, seriously.” If so, the server sends a signal to the phone that the CPU cores can be switched off again.

With that system of extensive checks, Apple wants to make sure that the phone doesn’t accidentally activate Siri without it being necessary, something that would cause annoyance to users. The system works more limited on the Apple Watch, because the watch has less processing power. On the Watch, Siri is allowed to use 5 percent of the processing power of the CPU cores when the screen turns on, when the user makes a wrist movement. If the watch doesn’t detect any movement, the software won’t listen to audio either.

It is the first time that Apple explains the operation of the command in such detail. The article appeared on the blog Apple started this summer about machine learning. Being able to publish research and present it at conferences is important for many scientists because it gives rise to prestige in the scientific world. Apple is a company that traditionally keeps much of its own research secret to try to gain an edge over competitors and keep new features a surprise for the public.