Ultra science – ultrasonics and man

“The baby inside womb is developing well”, “the patient is suffering from stones in the liver”, “something hard substance at 220 meters away from here” etc etc are certain statements we come across in our daily life. But we least bother about the science behind these things. It can be only possible by ‘ultra sound technology’.

Sound is a form of energy , which can travel in medium and is produced by the vibration of matter.

Vibrations produce a wide range of frequencies and of which can be heard are audible and can’t are un audible. We can hear sounds of frequencies ranging between 20Hz to 20KHz and are called audible, where as frequencies beyond 20kHz are ultrasound, can’t hear, but studied under ultrasonics.

• Ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater than about 20 kilohertz. The term sonic is applied to ultrasoundwaves of very high amplitudes. Hypersound, sometimes called praetersound or microsound, is sound waves of frequencies greater than 10¹³ hertz. At such high frequencies it is very difficult for a sound wave to propagate efficiently; indeed, above a frequency of about 1.25 × 10¹³ hertz it is impossible for longitudinal waves to propagate at all, even in a liquid or a solid, because the molecules of the material in which the waves are traveling cannot pass the vibration along rapidly enough.
• Many animals have the ability to hear sounds in the human ultrasonic frequency range. A presumed sensitivity of roaches and rodents to frequencies in the 40 kilohertz region has led to the manufacture of “pest controllers” that emit loud sounds in that frequency range to drive the pests away, but they do not appear to work as advertised.
• Some ranges of hearing for mammals and insects are compared with those of humans in the table.
• Frequency range of hearing for humans
  and selected animals

ANIMAL	frequency (hertz)
	low		high
humans	20		20,000
cats	100		32,000
dogs	40		46,000
horses	31		40,000
elephants	16		12,000
cattle	16		40,000
bats	1,000		150,000
grasshoppers and locusts	100		50,000
rodents	1,000		100,000
whales and dolphins	70		150,000
seals and sea lions	200		55,000

An ultrasound scan, also referred to as a sonogram, diagnostic sonography, and ultrasonography, is a device that uses high frequency sound waves to create an image of some part of the inside of the body, such as the stomach, liver, heart, tendons, muscles, joints and blood vessels.
Experts say that as sound waves, rather than radiation are used, ultrasound scans are safe. Obstetric sonography is frequently used to check the baby in the womb.
This article looks specifically at ultrasound scans. We also have articles in our knowledge center about CT scans, MRI scans and PET scans.
Ultrasound scans are used to detect problems in the liver, heart, kidney or the abdomen. They may also be useful in helping the surgeon when carrying out some types of biopsies.
The word "ultrasound", in physics, refers to all sound with a frequency humans cannot hear. In diagnostic sonography, the ultrasound is usually between 2 and 18 MHz. Higher frequencies provide better quality images, but are more readily absorbed by the skin and other tissue, so they cannot penetrate as deeply as lower frequencies. Lower frequencies can penetrate deeper, but the image quality is inferior.
According to MediLexicon's medical dictionary:
Diagnostic ultrasound is: "the use of ultrasound to obtain images for medical diagnostic purposes, employing frequencies ranging from 1.6 to about 10 MHz."
Therapeutic ultrasound is: "high intensity ultrasound causing coagulation necrosis of tissue, used in treatment of some benign tumors, such as uterine leiomyomata."
Ultrasound scans and sonograms
The difference between an ultrasound scan and a sonogram is:
• An ultrasound scan is the procedure, the event
• A sonogram is the image produced when an ultrasound scan is performed
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