Ultrasonic sound or Ultrasound
Ultrasonic sound is the term used for sound waves with frequencies greater than 20,000 Hz. These waves cannot be heard by the human ear, but the audible frequency range for other animals includes ultrasound frequencies. For example dogs can hear ultrasonic sound. Ultrasonic whistles are used on cars to alert deer to oncoming traffic so that they will not leap across the road in front of cars.
An important use of ultrasound is in examining inner parts of the body. Thus ultrasound is an alternative to X-rays. The ultrasonic waves allow different tissues such as organs and bones to be ‘seen’ or distinguished by bouncing of ultrasonic waves by the objects examined. The waves are detected, analysed and stored in a computer. An echogram is an image obtained by the use of reflected ultrasonic waves. It is used as a medical diagnostic tool. Ultrasonic sound is having application in marine surveying also.
· Ultra sound can be used in cleaning technology. Minute foreign particles can be removed from objects placed in a liquid bath through which ultrasound is passed.
· Ultrasounds can also be used to detect cracks and flaws in metal blocks.
· Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called ‘echo cardiography’.
· Ultrasound may be employed to break small ‘stones’ formed in the kidney into fine grains. These grains later get flushed out with urine.