Jaw Harp app
To find out what this instrument is and what it sounds like, go to YouTube.
To play music, turn the phone with the screen facing away from you, with the speaker holes facing up, and press it to your lower lip, as shown in the photo below.
When you briefly press a picture on the screen, a sound is heard. By changing the position of your lips and tongue, you can change the timbre of the sound in much the same way as when using a real musical instrument.
