The Noise Pollution is a type of energy pollution in which distracting, irritating, or    damaging sounds are freely audib...
In simple words the Noise Pollution can be defined   like the excess of sound thatdisrupts the normal conditions of   the ...
While the noise does not accumulate,         moved or maintained atthe time as the others types of pollutions,    can also...
Sounds are considered noise pollution if they adversely affect wildlife, human  activity, or are capable of damaging    ph...
The decibel (dB) is a measure of sound   intensity; that is, the magnitude of thefluctuations in air pressure caused by so...
The "A" filter (dBA) is the one most            frequently used.The "C" filter (dBC) puts more weight onlow-frequency soun...
The Noise pollution can affectboth your health and well being              in    several different ways.
Effects Of Noise On Humans  1. Auditory effects interfering withhearing; auditory fatigue and deafness.  2. Non-auditory e...
3. Physiological effects affecting     biological functions; anxiety,neurosis, insomnia, dizziness, nausea,       fatigue,...
4. Endocrine and hormonal changes relating to stress and noise levels.      i.e. raised adrenaline and              choles...
5. Psychological effects - physical and  mental fatigue, loss of concentration,     lower efficiency, reduced output, abse...
However, as more and more research are beingdone, more serious health risks have developed due        to the increase in n...
Changes in the immune system and birth defects have been attributed to noise  exposure, but evidence is limited.  Although...
Beyond these effects, elevated noise   levels can create stress, increase    workplace accident rates, andstimulate aggres...
Cardiovascular effects  Noise has been associated with importantcardiovascular health problems. In 1999, theWHO concluded ...
Industrial noise is usually considered   mainly from the point of view of  environmental health and safety as     sustaine...
Modern thinking in occupationalsafety and health identifies noise as hazardous to worker safety  and health in many places...
Noise also acts synergistically with other hazards      to increase the risk of harm to workers. In  particular, noise and...
No one on earth can escape the sounds of                   noise.In the past thirty years, noise in all areas,   especiall...
Noise can have a negative effect on humans,domestic and wild animals, ecologicalsystems, buildings and other structures.Ef...
Acoustic Pollution          Several years ago in the protection regulations of the environment noise was not considered to...
1. First, we must determine whether the noiselevel is such that it causes loss of audition. To                            ...
3. If it is established that the noise isgenerated by a machine, we should see how to modify it, so it produces less      ...
4. If after applying the earlierrecommendation, the discomfort by the noise  persists, provision for workers protective  e...
5. If the walls of the compound are    harsh acoustically, it will produce   echoes and reflections, which will       incr...
Noise-canceling headphonesThese reduce unwanted ambient sounds (i.e.,   acoustic noise) by means of active noise  control ...
Possible       Solutions•Auditory personalizedprotection•Absorbent materials•Acoustics barriers•Isolations
Personal ProtectionIt constitutes one of the most efficient methods          and simultaneously economic.   It is a questi...
VIBRATION
DEFINITION• VIBRATION IS OSCILATORY MOTION• A CYCLE OF SPECIFIC ACTIVITY BACK-  FORTH, UP AND DOWN RESULTING FROM  REVERSA...
RESPONSE DEPENDS ON:•   FREQUENCY OF VIBRATION•   AMPLITUDE OF VIBRATION•   TIME HISTORY OF VIBRATION EXPOSURE•   DIRECTIO...
MAGNITUDE IS INFLUENCED BY:• TYPE, WEIGHT, AND CONDITION OF TOOL• ACCELERATION AND FREQUENCY  PRODUCED BY TOOL – TOOL TYPE...
TYPES• WHOLE BODY VIBRATION• SEGMENTAL (HAND-ARM) VIBRATION
WHO’S AT RISK?• ANYONE WHO ABSORBS MACHINE  VIBRATION THROUGH THEIR HANDS AND  ARMS WHILE WORKING A FAST-MOVING  HAND TOOL...
HOW MANY EXPOSED• APPROXIMATELY 1.2 MILLION EXPOSED• 50 - 60 % OF WORKER POPULATION HAVE  SYMPTOMS
TOOLS MOST COMMONLY        ASSOCIATED:•   POWERED HAMMERS•   CHISELS, CHAIN SAWS•   SANDERS, GRINDERS, RIVETERS•   BREAKER...
WHAT IS VIBRATION SYNDROME• VASOSPASTIC, NEUROMUSCULAR,  ARTHRITIC DISORDERS OF THE  HANDS AND UPPER LIMBS• COMPOSITE OF V...
SYMPTOMS OF VIBRATION         SYNDROME•   DISCOMFORT FROM COLD•   TINGLING, NUMBING•   BLANCHING FINGERS•   PAIN
CONTROL STRATEGIES:           STRATEGIES• ENGINEERING AND WORK PRACTICES• ANTI-VIBRATION CLOTHING, EQUIPMENT  AND TRAINING...
ENGINEERING CONTROLS:• REDUCTION AT SOURCE• REDUCTION OF  TRANSMISSION• PROCESS MODIFICATION
REDUCTION AT SOURCE• REDUCE SPEED OF TOOL• REDUCE WEIGHT AND POWER NEEDED  TO DRIVE THE TOOL• CHANGE TYPE OF TOOL – E.G. R...
REDUCTION AT TRANSMISSION• PROVIDE CUSHION TO ACT AS A  VIBRATION ISOLATER IN A SEATED  TASK• PROVIDE ANTI-FATIGUE MATS FO...
PROCESS MODIFICATION• CHANGES IN ANY ASPECT OF PROCESS  TO ELIMINATE NEED FOR VIBRATING  TOOLS OR EQUIPMENT• USING MECHANI...
WORK MODIFICATION       APPROACHES• LIMIT NUMBERS OF HOURS• REDUCE NUMBER OF DAYS PER  WEEK• ROTATE BETWEEN VIBRATING AND ...
WORK PRACTICES•   LENGTH OF WORK DAY•   JOB ROTATION•   SELECT LOW VIBRATION TOOLS•   DESIGN WORK TASK AND WORKPLACE    ER...
ADMINISTRATIVE CONTROLS• PPE TO REDUCE TRANSMISSION OF  VIBRATING ENERGY TO THE HAND• PROTECT AGAINST EXPOSURE TO COLD  AN...
• Infrasound refers to waves or vibrations with a  frequency below the audibility range of the human  ear (i.e. < 20 Hz). ...
• Infrasound is especially dangerous, due to its  strong vibrations, or oscillations.• They hug the ground, travel for lon...
• Waves of infrasound are invisible, but  they slam into living tissues and physical  structures with great force.    The ...
EXAMPLES• Natural explosions from volcanoes produce  infrasonic waves. When Krakatau exploded, an  entire island was lifte...
Uses of infrasound:1. Medical: (therapeutic devices) - Several studies conducted in Russia and    Europe reported that inf...
2. Monitoring activities of the atmosphere:  - Infrasonic waves will be influenced by the  atmosphere during its propagati...
3. Forecasting natural disasters: Many disasters,  such as volcanic eruptions, earthquakes, land-  slides and clear-air tu...
• High-frequency sound waves that is above the  audibility range of the human ear [approximately  22kHz]; Wavelength of ab...
How does ultrasound work and how to     produce images of ultrasound?• Ultrasound waves images are produced by a  transduc...
• Ultrasound travels faster in dense  materials and slower in compressible  materials. In soft tissue sound travels at  ma...
Uses of ultrasound:1. Medical:• sonography: Ultrasound waves can be bounced    off of tissues using special devices. The e...
• Pulse echo visualization:• The information of objects is obtained by using  discrete lines of sight, with the transducer...
• Doppler effect:• Ultrasound based diagnostic imaging technique can  be enhanced with Doppler measurements, which  employ...
2. In animals:• For navigation: Bats use ultrasound for navigation. They send out ultrasounds and judges the distance of o...
Communication:• Whales make use of ultrasounds for  communication purposes. Individual pods  of whales have their own dist...
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  • YOU WILL BE ABLE TO: IDENTIFY INDUSTRIES AND JOBS IN WHICH OCCUPATIONAL VIBRATION IS A RECOGNIZED EXPOSURE EXPLAIN TO OUR INSUREDS THE EARLY SIGNS OF ILLNESS OR INJURY FROM WORKING WITH VIBRATING TOOLS CONDUCT SUBJECTIVE EVALUATIONS OF OCCUPATIONAL VIBRATION EXPOSURES AND RECOMMEND PRACTICAL CONTROLS TO MINIMIZE THE EXPOSURE
  • Transcript of "Noise"

    1. 1. The Noise Pollution is a type of energy pollution in which distracting, irritating, or damaging sounds are freely audible. As with other forms of energy pollution (such as heat and light pollution), noise pollution contaminants are not physical particles, but rather waves that interferewith naturally-occurring waves of a similar type in the same environment.
    2. 2. In simple words the Noise Pollution can be defined like the excess of sound thatdisrupts the normal conditions of the environment in a certain area.
    3. 3. While the noise does not accumulate, moved or maintained atthe time as the others types of pollutions, can also cause negative effects – - physiological, - psychological, - economic, - socially speaking to the quality of life if it is not controlled properly.
    4. 4. Sounds are considered noise pollution if they adversely affect wildlife, human activity, or are capable of damaging physical structures on a regular, repeating basis.In the broadest sense of the term, a sound may be considered noise pollution if it disturbs any natural process or causes human harm, even if the sound does not occur on a regular basis.
    5. 5. The decibel (dB) is a measure of sound intensity; that is, the magnitude of thefluctuations in air pressure caused by sound waves. The decibel scale is logarithmic, notarithmetic. This means that a doubling of sound intensity is not represented as a doubling of the decibel level. Decibels are usually measured with a filter that emphasizes sounds in certain frequencies.
    6. 6. The "A" filter (dBA) is the one most frequently used.The "C" filter (dBC) puts more weight onlow-frequency sounds such as the bass in amplified music. Normal conversation is around 60 dB.Noise of less than 75 dB, even for long periods is unlikely to damage your hearing.
    7. 7. The Noise pollution can affectboth your health and well being in several different ways.
    8. 8. Effects Of Noise On Humans 1. Auditory effects interfering withhearing; auditory fatigue and deafness. 2. Non-auditory effects interfering with social behaviour; problems with communications, sleep, recreation, mental equilibrium (peace), and the ability to concentrate at work
    9. 9. 3. Physiological effects affecting biological functions; anxiety,neurosis, insomnia, dizziness, nausea, fatigue, visual symptoms, hypertension, cardiovascular symptoms, liver changes, nervous symptoms, changes in skin, fast irregular heart beats (tachycardia).
    10. 10. 4. Endocrine and hormonal changes relating to stress and noise levels. i.e. raised adrenaline and cholesterol.Noise causes blood vessels to close cutting down blood supply to the fingers and toes. Respiratory changes occur due to noise.
    11. 11. 5. Psychological effects - physical and mental fatigue, loss of concentration, lower efficiency, reduced output, absenteeism, higher rates of accidents, behavioural changes, errors at work, loss of sleep, psychosomatic disorders, diseases related to stress, mental illness, aggravation of existing stress problems and mental illness, neurotic effects, rage anger, crime.
    12. 12. However, as more and more research are beingdone, more serious health risks have developed due to the increase in noise pollution.- Hearing loss (conductive or sensorineural) - Hypertension - Aggressive behavior - Serious sleep loss - Heart disease (stress related)- Danger to people - cover warning signals &: Cause accidents
    13. 13. Changes in the immune system and birth defects have been attributed to noise exposure, but evidence is limited. Although some presbycusis may occur naturally with age, in many developed nations the cumulative impact of noise issufficient to impair the hearing of a largefraction of the population over the course of a lifetime.
    14. 14. Beyond these effects, elevated noise levels can create stress, increase workplace accident rates, andstimulate aggression and other anti- social behaviors. The most significant causes arevehicle and aircraft noise, prolonged exposure to loud music, and industrial noise.
    15. 15. Cardiovascular effects Noise has been associated with importantcardiovascular health problems. In 1999, theWHO concluded that the available evidence showed a weak association between long-term noise exposure above 67-70 dB(A) andhypertension. Recent studies have suggested that noise levels of 50 dB(A) at night may also increase the risk of myocardial infarction by chronically elevating cortisol production
    16. 16. Industrial noise is usually considered mainly from the point of view of environmental health and safety as sustained exposure can cause permanent hearing damage. Traditionally, workplace noise has been a hazard linked to heavy industries such as ship-building and associated only with noise induced hearing loss (NIHL).
    17. 17. Modern thinking in occupationalsafety and health identifies noise as hazardous to worker safety and health in many places ofemployment and by a variety of means.
    18. 18. Noise also acts synergistically with other hazards to increase the risk of harm to workers. In particular, noise and dangerous substances (e.g. some solvents) that have some tendencies towards ototoxicity may give rise to rapid ear damage. A-weighted measurements are commonly usedto determine noise levels that can cause harm tothe human ear, and special exposure meters are available that integrate noise over a period of time to give an Leq value (equivalent sound pressure level), defined by standards.
    19. 19. No one on earth can escape the sounds of noise.In the past thirty years, noise in all areas, especially in urban areas, have been increasing rapidly.There are numerous effects on the humanenvironment due to the increase in noise pollution.
    20. 20. Noise can have a negative effect on humans,domestic and wild animals, ecologicalsystems, buildings and other structures.EffectPhysical effects from noise include:vibration to buildings,damage to glass windows,plaster cracking,damage to building foundations.Jet aircraft have damaged roadsand buildings.
    21. 21. Acoustic Pollution Several years ago in the protection regulations of the environment noise was not considered to be the pollutant. Then in all the countries of the world there have been elaborated procedure and bylaws that they entrust of the protection of the environment against the excess of noise. The most serious efforts of the international communities aretranslated in policies of prevention and control of the sonorous pollution.
    22. 22. 1. First, we must determine whether the noiselevel is such that it causes loss of audition. To audition do it, comparing measurements made with established norms, which indicate noise level by activity and exposure times, partners both are taken corrective action to reduce harmful levels of noise.2. It is known that a noise level below 85dB (A) does not cause harm to the employee. employeeHowever, it can be very annoying, depending on the activity taking place.
    23. 23. 3. If it is established that the noise isgenerated by a machine, we should see how to modify it, so it produces less noise. Sometimes lowering its speed is sufficient. You can also make a total closure of the machine, or you can exchange it for another quieter.
    24. 24. 4. If after applying the earlierrecommendation, the discomfort by the noise persists, provision for workers protective equipment such as earmuffs and ear plugs should be done. Important is to ensure that workers use the equipment properly, motivating and monitoring their use, particularly when the noise level may injure over time, their hearing ability.
    25. 25. 5. If the walls of the compound are harsh acoustically, it will produce echoes and reflections, which will increase the sound pressure. In this case, we should seek absorbent materials for coating the walls,especially if there are machines located close to these walls. This will reduce the sound pressure.
    26. 26. Noise-canceling headphonesThese reduce unwanted ambient sounds (i.e., acoustic noise) by means of active noise control (ANC). Essentially, this involves using a microphone, placed near the ear, and electronic circuitry which generates an "antinoise" sound wave with the opposite polarity of the sound wave arriving at the microphone. This results in destructive interference, which cancels out the noisewithin the enclosed volume of the headphone.
    27. 27. Possible Solutions•Auditory personalizedprotection•Absorbent materials•Acoustics barriers•Isolations
    28. 28. Personal ProtectionIt constitutes one of the most efficient methods and simultaneously economic. It is a question of the auditory stopperscalled (or acoustic shells), that they have the ability to reduce the noise in almost 20 dB, dB which allows that the person who uses them could be located in very noisy environments without any problem. Very used by the workmen and other workers of some noisy industries.
    29. 29. VIBRATION
    30. 30. DEFINITION• VIBRATION IS OSCILATORY MOTION• A CYCLE OF SPECIFIC ACTIVITY BACK- FORTH, UP AND DOWN RESULTING FROM REVERSAL OF ENERGY• FREQUENCIES OF 100 HZ OR HIGHER ARE ABSORBED BY THE HANDS AND WRISTS• FREQUENCIES UNDER 100 HZ ARE ABSORBED BY THE UPPER LIMB JOINTS
    31. 31. RESPONSE DEPENDS ON:• FREQUENCY OF VIBRATION• AMPLITUDE OF VIBRATION• TIME HISTORY OF VIBRATION EXPOSURE• DIRECTION OF VIBRATION• POINT OF APPLICATION OF VIBRATION• HOW MUCH VIBRATION IS TRANSMITTED• AFFECT OF CLOTHING AND EQUIPMENT• BODY SIZE (HEIGHT AND WEIGHT)• BODY POSTURE/ BODY TENSION POSTURE
    32. 32. MAGNITUDE IS INFLUENCED BY:• TYPE, WEIGHT, AND CONDITION OF TOOL• ACCELERATION AND FREQUENCY PRODUCED BY TOOL – TOOL TYPE, ENVIRONMENTAL, ANTI-VIBRATION MATERIAL – OPERATING SPEED, ERGONOMICS OF USE• GRIPPING FORCES• ORIENTATION AND POSTURE OF THE HANDS, ARMS, AND BODY DURING WORK• PARTS OF HANDS IN DIRECT CONTACT WITH THE VIBRATING SURFACE
    33. 33. TYPES• WHOLE BODY VIBRATION• SEGMENTAL (HAND-ARM) VIBRATION
    34. 34. WHO’S AT RISK?• ANYONE WHO ABSORBS MACHINE VIBRATION THROUGH THEIR HANDS AND ARMS WHILE WORKING A FAST-MOVING HAND TOOL --• OR THROUGH THE BUTTOCKS AND THE SOLES OF THE FEET WHILE RIDING IN OR STANDING NEAR VIBRATING, HEAVY MACHINERY--• RUNS THE RISK.
    35. 35. HOW MANY EXPOSED• APPROXIMATELY 1.2 MILLION EXPOSED• 50 - 60 % OF WORKER POPULATION HAVE SYMPTOMS
    36. 36. TOOLS MOST COMMONLY ASSOCIATED:• POWERED HAMMERS• CHISELS, CHAIN SAWS• SANDERS, GRINDERS, RIVETERS• BREAKERS, DRILLS, COMPACTORS• SHARPENERS, SHAPERS
    37. 37. WHAT IS VIBRATION SYNDROME• VASOSPASTIC, NEUROMUSCULAR, ARTHRITIC DISORDERS OF THE HANDS AND UPPER LIMBS• COMPOSITE OF VIBRATION INDUCED SIGNS AND SYMPTOMS (e.g. NUMBNESS, TINGLING OF THE FINGERS, EPISODIC BLANCHING OF THE FINGERS, PAIN, REDUCED GRIP STRENGTH AND DEXTERITY
    38. 38. SYMPTOMS OF VIBRATION SYNDROME• DISCOMFORT FROM COLD• TINGLING, NUMBING• BLANCHING FINGERS• PAIN
    39. 39. CONTROL STRATEGIES: STRATEGIES• ENGINEERING AND WORK PRACTICES• ANTI-VIBRATION CLOTHING, EQUIPMENT AND TRAINING• GOALS: – REDUCE THE INTENSITY – REDUCE THE EXPOSURE DURATION – IDENTIFY THE EARLY SIGNS AND SYMPTOMS
    40. 40. ENGINEERING CONTROLS:• REDUCTION AT SOURCE• REDUCTION OF TRANSMISSION• PROCESS MODIFICATION
    41. 41. REDUCTION AT SOURCE• REDUCE SPEED OF TOOL• REDUCE WEIGHT AND POWER NEEDED TO DRIVE THE TOOL• CHANGE TYPE OF TOOL – E.G. RECIPROCATING ENGINE TO ROTARY OR ELECTRIC MOTOR• TOOL MAINTENANCE• MOUNT EQUIPMENT ON SPRINGS OR COMPRESSION PADS• USE MATERIALS THAT GENERATE LESS VIBRATION
    42. 42. REDUCTION AT TRANSMISSION• PROVIDE CUSHION TO ACT AS A VIBRATION ISOLATER IN A SEATED TASK• PROVIDE ANTI-FATIGUE MATS FOR STANDING OPERATION• DESIGN TOOLS TO REDUCE VIBRATION TRANSMITTED TO THE HANDS,• COUNTER WEIGHT TOOLS TO MINIMIZE GRIPPING REQUIRED TO OPERATE THEM – DAMPENING MATERIALS AND GLOVES ARE USUALLY MORE EFFECTIVE FOR HIGHER
    43. 43. PROCESS MODIFICATION• CHANGES IN ANY ASPECT OF PROCESS TO ELIMINATE NEED FOR VIBRATING TOOLS OR EQUIPMENT• USING MECHANICAL AIDS (CHUCKS, CLAMPS) TO HOLD MATERIAL – REDUCES TIME OR INTENSITY OF EXPOSURE• ROBOTICS• AUTOMATION• SUBSTITUTION OF MATERIALS – PLASTICS FOR HARD METAL
    44. 44. WORK MODIFICATION APPROACHES• LIMIT NUMBERS OF HOURS• REDUCE NUMBER OF DAYS PER WEEK• ROTATE BETWEEN VIBRATING AND NON-VIBRATING TOOL TASKS• SCHEDULE MAINTENANCE BREAKS
    45. 45. WORK PRACTICES• LENGTH OF WORK DAY• JOB ROTATION• SELECT LOW VIBRATION TOOLS• DESIGN WORK TASK AND WORKPLACE ERGONOMICALLY• REDUCE GRIP FORCE APPLIED• REDUCE FORCE APPLIED• RESTRICT USE OF PIECE WORK AND INCENTIVE PAY• ERGONOMIC WORK POSTURES
    46. 46. ADMINISTRATIVE CONTROLS• PPE TO REDUCE TRANSMISSION OF VIBRATING ENERGY TO THE HAND• PROTECT AGAINST EXPOSURE TO COLD AND TRAUMA• TRAINING – SOURCE OF VIBRATION – ADVERSE HEALTH AND SAFETY EFFECTS – EARLY SIGNS AND SYMPTOMS – USE AND AVAILABILITY OF VIBRATION PROTECTIVE CLOTHING – ANTI-VIBRATION DEVICES – VALUE OF GOOD TOOL MAINTENANCE – WORK PRACTICE PROCEDURES
    47. 47. • Infrasound refers to waves or vibrations with a frequency below the audibility range of the human ear (i.e. < 20 Hz). Hence, these waves cannot be heard by humans.• They can be felt and, as studies have shown, they produce a range of effects in some people including anxiety, extreme sorrow, and chills.• Infrasonic waves can carry over long distances [thousands of kilometres] and are less susceptible to disturbance or interference than waves of higher frequencies.• Infrasound may be produced by wind, types of earthquakes, ocean waves, and certain things such as avalanches, volcanoes, and meteors etc…
    48. 48. • Infrasound is especially dangerous, due to its strong vibrations, or oscillations.• They hug the ground, travel for long distances without losing strength, and are unstoppable.• Furthermore, not much amplitude is needed to produce negative effects in the human body.• Therefore, even mild infrasound exposure requires several hours, or even days, to reverse the resulting symptoms.
    49. 49. • Waves of infrasound are invisible, but they slam into living tissues and physical structures with great force. The sensation vibrates internal organs and buildings, flattening objects as the sonic wave strikes. At certain pitches, it can explode matter.
    50. 50. EXAMPLES• Natural explosions from volcanoes produce infrasonic waves. When Krakatau exploded, an entire island was lifted 100 miles into the air, and windows were shattered 1,000 miles away from ground zero. The shock waves, affecting both earth and atmosphere, continued for hours.• Explosives, such as atomic weapons, produce weapons infrasound. Zone one is ground zero and its destruction. Zone 2 is a powerful, speeding, sonic wave of reduced air pressure. This concussion blast travels at great distances away from ground zero and few survive its destructive path.
    51. 51. Uses of infrasound:1. Medical: (therapeutic devices) - Several studies conducted in Russia and Europe reported that infrasound has therapeutic effects. - Infrasound peumomassage: At 4 Hz, the progression of myopia in school children can be stabilized. - Infrasound phonophersis in antibacterial drugs: In treatment of patients with bacterial keratitis, it is as effective as local instillations of the same drugs.
    52. 52. 2. Monitoring activities of the atmosphere: - Infrasonic waves will be influenced by the atmosphere during its propagation, which is closely related with the distribution of temperature and wind in the atmosphere. - By measuring the propagation properties of infrasonic waves generated by natural sources, one can detect some characteristics and rules of the large scale meteorological motions.
    53. 53. 3. Forecasting natural disasters: Many disasters, such as volcanic eruptions, earthquakes, land- slides and clear-air turbulences, radiate infrasound in advance. By monitoring the infrasound waves, we can forecast these disasters. FUN FACTS! Elephants have the ability to emit infrasound to communicate at distances of up to 10 miles (12 - 35 Hz.). Even tigers emit infrasound. “Odd sensations that people attribute to ghosts may be caused by infrasonic vibrations” -- Psychologist Richard Wiseman of the University of Hertfordshire
    54. 54. • High-frequency sound waves that is above the audibility range of the human ear [approximately 22kHz]; Wavelength of about 1.5 mm• Sound cannot be heard but can be emitted and detected by special machines• The speed of ultrasound does not depend on its frequency; it depends on what material or tissue it is travelling in. in Both the mass and spacing of the molecules and the attracting force between the particles of the material have effects on the speed of the ultrasound as it passes through.
    55. 55. How does ultrasound work and how to produce images of ultrasound?• Ultrasound waves images are produced by a transducer.• A transducer is a device that takes power from one source, converts the energy into another form, and delivers the power to another target.• In this case, the transducer acts as a loudspeaker or a microphone, it converts electrical signals to ultrasound waves, and picks up the reflected waves, converting them back into electrical signals.• The electrical signals returned to the transducer are used to form pictures on a television screen.
    56. 56. • Ultrasound travels faster in dense materials and slower in compressible materials. In soft tissue sound travels at materials 1500 m/s, in bones about 3400 m/s, and in air 330 m/s.• Travels freely through fluid and soft tissues but is reflected back as echoes when it hits a more solid/dense surface• When the ultrasound hits different structures in the body of different density, it sends back echoes of varying strength
    57. 57. Uses of ultrasound:1. Medical:• sonography: Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram.• Ultrasound is often used to examine a foetus during pregnancy, or a fatal heart.• Ultrasound usually ranges from one MHz (one million cycles per second) to 20 MHz. This is because tissues absorb higher frequency energy more readily, hence producing fainter images.
    58. 58. • Pulse echo visualization:• The information of objects is obtained by using discrete lines of sight, with the transducer position and orientation which defines the line of sight and the delay of received echoes, which is used to determine the range of the echo-producing object.• It can be used in a wide range of clinical conditions and is useful in many parts of the body.• There are 3 modes of the pulse echo visualization (i.e. A-mode, M-mode, and B-mode)
    59. 59. • Doppler effect:• Ultrasound based diagnostic imaging technique can be enhanced with Doppler measurements, which employ the Doppler effect to assess whether structures (usually blood) are moving towards or away from the probe, and its relative velocity.• The principal applications of Doppler effect are in cardiac and peripheral vesicular diagnostic specialties. Current qualitative applications involve 2 aspects of blood flow evaluation. Doppler devices are primarily concerned with the detection and evaluation of blood flow disturbances resulting from valves and septal defects.
    60. 60. 2. In animals:• For navigation: Bats use ultrasound for navigation. They send out ultrasounds and judges the distance of objects ahead of them, or what the objects are, by the received echoes. This allows them to catch flying insects while flying full speed in pitch darkness.
    61. 61. Communication:• Whales make use of ultrasounds for communication purposes. Individual pods of whales have their own distinctive dialect of calls, similar to songbirds.• Singing whales are usually solitary males who exhibit it in a shallow smooth- bottomed area where sound propagates well. They are interpreted as territorial and mating calls.
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