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!
ANSWER: There is limited data on how well electronic or high-frequency sound devices work for household pest control. These devices may be called ultrasonic, electronic, microvibration or electromagnetic pest repellers.The manufacturers state that they use high-frequency sound waves or electromagnetic output to repel insects (cockroaches, fleas, house flies, mosquitoes, rodents, moles, and other pests).ut rodents seem to learn to avoid the mechanisms used. Mice quickly become accustomed to regularly repeated sounds. Ultrasonic sounds have limited use in rodent control because they are directional and do not penetrate behind objects.