Why is the term Roger Wilco considered by some to be an incorrect phrase - trivia question /questions answer / answers
Aerophones; any class of musical instruments in which a vibrating mass of air produces the initial sound including bull roarers and sirens. They are found in many countries throughout Africa and are normally incorporated with dancing, the musicians having to synchronize their footwork along with playing their notes!
For theaters and other public buildings, the Americans with Disabilities Act mandates that earphone listening devices be provided on-site. Those devices use infrared light waves or an FM radio signal to transmit sound from the performers' microphones, she notes.