The theremin was one of the first electronic music instruments invented by Soviet inventor Léon Theremin in the 1920s. Performers could change the pitch and volume of the sound emitted by the instrument by moving their hands over two separate antennas without needing to touch anything.

Create your own digital version of the theremin using an Arduino, and ultrasonic distance sensor, and a buzzer. You can choose whether to change pitch or volume relative to the distance of the user's hand over the sensor.

Hint: it may help to look at a list of common frequencies of another instrument, such as a piano, to determine what frequency to play out of the speaker. You will also want to find out the minimum and maximum distance that your ultrasonic distance sensor can measure.