Table Of Contents: Practical Applications of Sound
Sound waves cause the air around us to vibrate. When these vibrations reach our ears, the interaction produces what we call sound. The outer ear captures the sound as vibrating air molecules. The vibrating air causes the eardrum to vibrate. Three small bones in the middle ear carry the vibrations to the cochlea. The cochlea has tiny hairs which send a message to the brain along the auditory nerve. The brain processes the information it receives and interprets it as sound.
Some animals use a biological process called echolocation to help them hunt and navigate in the dark. Echolocation is the ability to locate a distant or a concealed object by reflecting sound waves off of the object. This is done by measuring the time taken for an echo to return and calculating the direction the echo came from. For example, a bat can send ultrasonic waves which reflect off of an insect and return to the bat’s ears. The bat then uses this reflected sound to pin point the exact location of the insect.
Although humans cannot hear ultrasonic waves, we have found many ways to use them. Ultrasonic devices are used in navigation, detection and location of objects and even medicine. For example, doctors use ultrasound waves to look inside the human body. Ultrasound waves enter the body and reflect off of internal body organs. These waves reflect differently off the different organs. An ultrasound device uses the reflected waves to make a picture called a sonogram. Sonograms can be used to find and treat medical conditions, as well as to examine developing babies before they are born.
Sonar stands for sound navigation and ranging. It is used to find the depth of water, map the ocean floor, and locate objects such as sunken ships. A sonar device sends a burst of ultrasound waves downward through the water. The waves strike a barrier, such as a sunken ship, and are reflected back. The device detects the waves and records how long it takes for the original wave to leave and return. A computer uses the speed of sound in water and the time for the wave to make a round trip to calculate the depth of the object.