Knock: Tap Your Desk

Your phone is standing on the desk. Your hands are on the keyboard. Knock on the table, and the reel scrolls.

Knock listens for knocks on the desk around your phone and turns them into commands. Using the phone's two microphones and its motion sensor, it tells a knock right in front of the phone from one further away, and two knocks from three. That gives you four commands for each table:

- Knock twice near the phone: scroll down
- Three times near: scroll up
- Twice far away: open your assistant
- Three times far away: play or pause music

Change any of them to go back, go home, open recent apps, notifications or quick settings, swipe, take a screenshot, lock the screen, switch the flashlight, skip a track, or open any app.

TEACH IT YOUR DESK
Every table sounds different, so Knock learns yours. Stand the phone in its holder, knock eight times on two spots, and it is ready in about a minute. Teach it again any time to make it sharper. Use it at more than one desk? Give each table its own profile.

BUILT TO IGNORE EVERYTHING ELSE
Typing, your mouse, a mug set down, music or videos playing from the phone itself: Knock is tuned to tell these apart from a deliberate knock. Single knocks never do anything. Practice mode lets you try it without running any actions.

ACCESSIBILITY SERVICE: WHAT IT IS FOR
To carry out your commands, Knock uses Android's AccessibilityService API. When you knock a command, its service performs the action you chose: scroll, swipe, back, home, recent apps, notifications, quick settings, screenshot or lock screen. It acts only right after a knock you taught it. It does not read, collect or store anything on your screen. It stays off until you turn it on in Android's Accessibility settings, after Knock explains this in the app, and you can turn it off there any time.

PRIVATE BY DESIGN
Knock has no internet permission. What the microphone hears is processed on the phone as it arrives and never recorded or sent anywhere. While Knock is listening, Android shows its microphone indicator and Knock shows a notification with an off switch. No account, no ads, no analytics.

Works best with the phone standing still in a holder or stand on a solid desk. Phones that give apps two separate microphones can tell spots apart; on others you still get two commands from one spot.