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!
Assistive Listening Devices. Assistive listening devices (ALDs) or assistive listening systems include a large variety of devices designed to help you hear sounds in everyday activities. ALDs are available in some public places such as auditoriums, movie theaters, houses of worship, and meeting rooms.