You need to start an Activity with only the Action set to android.intent.action.VOICE_ASSIST and the Google Now Speech recognizer pops up. Try this using the developer tools: adb shell am start -a android.intent.action.VOICE_ASSIST

Pro tip: Use Google Now to launch your next Android app Nov 18, 2014 Touchless Control – Republic Help Some commands result in a search query Both Moto Voice and Google Voice Search work by associating what you say to a specific command like the weather, time, calling, etc.. If there isn't a command or special response for your query, Google Voice Search will return a web search result. Can't play media 4 Ways to Use Google Voice Search - wikiHow

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