Katz Chapter 6: Transducers for Audiologic Testing

What is a transducer?

Transducer- a device that converts ______energy into ______energy

For audiology, two main types:

1)Those that convert ______energy to ______energy (microphones)

2)Those that convert ______energy to acoustic or ______energy (earphones, loudspeakers, and bone vibrators)

Selecting an appropriate transducer

Price of a transducer depends on:

1)the broadness of the ______response

2)the ______of its frequency response

3)its ______range

4)the ______of the signal that it must reproduce (only an issue of very brief signals, less that a few ms)

Transducers have a max output. If you push it beyond the maximum, the output will be ______.

Must match the output impedance from the ______to the input impedance of the ______

Air Conduction

-What is the use to the transducer?

  • if you need to test ______ear at a time, ear phones or insert instead of sound field

-Is there too much ambient noise?

  • use ______which have a better seal than supra-aural ear phones (not a problem with a sound booth)

-Supra-aural Earphones

  • Disadvantages:
  • Air leak is possible without careful ______
  • Pressure on pinna can ______ear canal
  • Unable to reproduce ______signals accurately
  • ______frequency response
  • Creation of ______effect
  • Reduced ______l attenuation
  • Why do we still use them?
  • For audiometric pure tone testing, many of these disadvantages are not an issue
  • All of the studies from the last 50 years have used earphones
  • They’re reliable
  • They’re easy to use

-Circumaural Earphone Cushions

  • Use:
  • To reduce the ______effect
  • For attenuating ______noise in the test booth
  • More ______that supra-aural cushions
  • Problems:
  • ______issues
  • Don’t fit standard ______
  • Use not recommended because of the ______issue

-Headset (headband)

  • Can’t really separate ______from headband
  • Hand held ear phones:
  • Have low ______
  • Low validity
  • Lack of ______fit, resulting in loss of sound
  • Inconsistent relationship between the ______and the eardrum
  • Increase in SPL if held too ______to the ear
  • Only advantage: solves the problem of headbands not fitting ______heads
  • Solution: find children’s headband, use inserts

-Insert Receivers (ER-3A)

  • Uses a tube coupled to a the ear by a ______insert
  • Advantages:
  • Completely fill all but the most ______ear canals
  • Less ______effect than supra-aurals
  • Less ______attenuation than supra-aurals
  • Disposable
  • Disadvantages
  • Cannot use with a ______ear
  • Initial concerns about calibration have been resolved
  • Must be sure of a straight, ______insertion to receive all benefits

-Loudspeakers

  • used for ______testing (tones, speech and noise)
  • when patient:
  • will not ______headphones, inserts
  • head is too ______for headphones
  • needed for a specific ______(HA eval, CI eval)
  • hard to calibrate
  • many factors affect testing: head position, standing waves, etc

-Bone Conduction

  • used to measure ______reserve
  • not great for ______
  • minimal ______attenuation

-Microphones

  • transducer that changes ______signal to ______signal
  • modern microphones have a fairly ______and flat response that makes it easier to modify its output
  • the specific type of microphone needed in a situation depends on its _____

-Types of Microphones

  • Communication
  • When used simply to communicate with the patient (and not for testing) a microphone does not need a very ______frequency response range or broad dynamic range
  • However, audiologists tend to use the same microphone for both speech testing and communication therefore, the microphone be adequate for clear ______signals
  • Live voice testing
  • Here it is important that the microphone have a ______frequency response range to encompass all English phonemes