1) A robust tuning fork that maintains its sound output for several seconds. Move the fork toward or away from your audience to exhibit the shift in frequency.
2) A piezo siren is incased in a ball and thrown across the room or swung in a circle on the end of a string.
3) A reed is mounted on the end of a tube and the tube is spun as air is blown into the tube to make it sound. Tube can be mounted on a motor or hand rotor.
Questions:
When is the sound highter/lower?
Would this work on the moon?
