Update 10/20/17: Some users are reporting that this feature is rolling out. Those users are reporting that they saw a notification telling them to retrain their hotword with "Hey Google." Check your notifications to see if the feature is out for you!
The Google Pixel 2 and Google Pixel 2 XL were officially announced just 10 days ago, and while they have yet to reach the hands of consumers they are bring showcased at Verizon Wireless stores throughout the United States. We've been digging in to the Pixel 2's system applications to bring you the latest Pixel Launcher and Google Camera app, but we've also been looking for more hidden aspects such as the dark quick settings theme and evidence for Bluetooth battery level reporting. Most of the Google apps pre-installed on the Pixel 2 aren't new with one notable exception—the Google App. Version 7.3.28.21 of the Google App can only be found on the Pixel 2/Pixel 2 XL and it hints at "Hey Google" hotword detection coming to Google Assistant on phones.
Although an APK teardown can often predict features that may arrive in a future update of an application, it is possible that any of the features we mention here may not make it in a future release. This is because these features are currently unimplemented in the live build and may be pulled at any time by Google in a future build.
"Hey Google" Hotword Detection coming to Google Assistant
Currently, there is only one hotword that can trigger Google Assistant on smartphones. You have to say "Ok Google" to make Assistant start listening. Many of you may have grown accustomed to this hotword, but for many of us who own a Google Home device there's another way to activate Assistant. The other hotword that is only available on Google Home devices is "Hey Google." Personally, I think this hotword rolls off the tongue far more naturally and so I exclusively say "Hey Google" to wake my Google Home.
That's why I was excited to find the following strings in this latest Google App version on the Pixel 2:
<string name="hotword_enrollment_summary_text_screen_assistant_device">Your Assistant can now recognize your voice when you say \"%1$s\" or \"%2$s\".</string>
<string name="hotword_enrollment_summary_usage_example_first">"Ok Google, what's my name?"</string>
<string name="hotword_enrollment_summary_usage_example_second">"Hey Google, what's the traffic to work?"</string>
<string name="hotword_enrollment_summary_usage_example_third">Ok Google, tell me about my day.</string>
As you can see, the app advertises that Assistant can recognize your voice when you say one of two hotwords. Those two hotwords are elaborated on in the next few lines: "Ok Google" or "Hey Google."
Compare this to the same set of lines from the existing Google app version on the Play Store:
<string name="hotword_enrollment_summary_text_screen_assistant_device">Your Assistant can now recognize your voice.</string>
<string name="hotword_enrollment_summary_usage_example_first">"%1$s, what's my name?"</string>
<string name="hotword_enrollment_summary_usage_example_second">"%1$s, what's the traffic to work?"</string>
<string name="hotword_enrollment_summary_usage_example_third">%1$s, tell me about my day.</string>
Before, the app only tells you that a single hotword will work to wake Assistant (we know this to be "Ok Google").
I haven't been able to confirm if "Hey Google" hotword detection can indeed be enabled on the latest Google App version. That's because, unfortunately, the Google App version that I extracted from the Pixel 2 is incomplete—I need to grab the odex file too. Furthermore, the Verizon demo unit obviously didn't allow me to add a Google account so I'm unable to train Google Assistant in store to see if "Hey Google" is an accepted phrase.
Once I get my hands on the Google Pixel 2 XL, I'll be sure to let you guys know if you can indeed use "Hey Google" to talk to your phone.