While most musical instruments rely on air or the vibration of air to produce sound, there are a few examples of instruments that don't use air as the primary medium. Here are some examples:
Electric guitar: Electric guitars produce sound through the amplification of the strings' vibrations by electromagnetic pickups. The pickups convert the string vibrations into electrical signals, which are then amplified and output through speakers.
Electric bass: Similar to the electric guitar, electric bass guitars generate sound through the amplification of the strings' vibrations by electromagnetic pickups.
Theremin: The theremin is an electronic instrument that uses two antennas to control pitch and volume. It relies on the interaction of the player's hands with the antennas to create electromagnetic fields, and the movement of the hands within those fields produces the desired sounds.
Electronic keyboards: Digital or electronic keyboards produce sound through electronic circuits and synthesized sounds. They don't rely on air vibration but instead use oscillators, samples, and various digital processes to create and manipulate sound.
Electric violin: Electric violins are similar to electric guitars, using pickups to convert the vibrations of the strings into electrical signals. These signals are then amplified and output through speakers.
Electronic drums: Electronic drum kits produce sound by triggering electronic sounds stored in a module when the drum pads or triggers are struck. The sound is produced through electronic circuits and played back through speakers or headphones.
These instruments demonstrate how technology and electronics can be used to create sound without relying on the vibration of air as the primary mechanism.