SOUND: Sound is waves produced by vibrations, such as those generated by the string instruments of a guitar or the vocal cords of the larynx. These waves are transmitted through air or water. Sound waves that reach the receiver’s ears usually through the air at 340m/s in the case of human beings, where they are perceived by the eardrum, which is a very sensitive membrane. Aquatic animals are capable of perceiving waves transmitted through water to communicate with each other. In water, sounds travel faster and with fewer losses. At speeds ranging between 1400 and 1600 m/s. Ultrasonic sounds have been very useful for boats.