sound.txt

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Author:
jpowell22
ID:
117420
Filename:
sound.txt
Updated:
2011-11-16 23:15:07
Tags:
maureen
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Description:
11-10-11
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  1. What is an ultrasound?
    high frequency sound waves that can be converted to heat

    mechanical vibrations produced by oscillatory molecules
  2. What are the 3 aspects of sound?
    1. source- something within has to be vibrating.

    2. energy is transferred from the source in the form of longitudinal sound waves

    3. sound must be detected by ear or instrument
  3. What are sound waves?
    longitudinal waves that are transmitted through almost any substance - solid, liquid, or gas
  4. Do sound waves travel faster and lose less energy in liquids/solids, or air?
    liquids/solids

    *ear to train tracks
  5. What is loudness?
    sensation of listner related to the energy in the sound wave
  6. What depends on frequency and amplitude?
    loudness
  7. What is pitch?
    sensation of listener to a high or low pitch
  8. What depends on frequency?
    pitch
  9. What is the human audible range?
    20-20,000 Hz
  10. Above human hearing range is called what?
    ultrasonic

    >20,000Hz
  11. Below human hearing range is called what?
    infrasonic

    <20Hz
  12. What are the 4 steps for conversion of the ultrasound?
    1. pulse of US is emitted by a transducer

    2. crystal in transducer expands and contracts

    3. linear progagation of waves through the tissue (lining up)

    4. US is reflected at the interface where the tissues meet -> causes friction -> which causes heat
  13. What is the frequency of ultrasound?
    1,000,000Hz - 3,000,000Hz

    1MHz - 3MHz
  14. What is a transducer?
    head of US - electrical device that transforms an electrical pulse into mechanical vibrations
  15. What is the Piezoelectric effect?
    piezoelectric crystal - pressure from electrical current is exerted on the crystal in the US head

    pressure results in mechanical vibrations
  16. When is the only time sound waves are seen or felt?
    when reflected under water
  17. What does not transmit sound waves?
    air
  18. What may occur is US is on and the sound head is held in the air?
    crystal will shatter

    melt the cement in the unit

    transducer head will get really hot
  19. What are some coupling/medium agents used with US?
    aquasonic gel

    water

    creams/lotions

    medicated creams/lotions

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