Hold a note.

What this is for

• Tuning by ear — play A4 (440Hz) and tune your A string until the wobble disappears. The wobble is "beating" — when two slightly-different frequencies interfere.
• Vocal warmups — sing a long held tone over the drone. Sirens, lip rolls, sustained vowels.
• Drone meditation — sit with a sustained tone. Indian classical music calls this the "tanpura." A5 is bright, A3 is grounding.
• Interval ear training — hit "+ add second note," set them to a third / fifth / octave apart, hold both. Learn the sound of each interval.

Hold spacebar to toggle play. Press a note's letter (A-G, or # for sharps) to change pitch.