AUDIOMETER CARE AND CALIBRATION

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AUDIOMETER CARE AND CALIBRATION

• THE AUDIOMETRIC TEST ENVIRONMENT

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Audiometric Test Booth

• The noise levels within the test booth must not
  exceed specified levels.
• Army - Chapter 7, Table 7-1 DA PAM 40-501 (same
  as listed in the DODINST 6055.12)
• Navy - American National Standards Institute
  Criteria
• for Maximum Permissible Ambient Noise
  Levels
• for Audiometric Test Rooms (ANSI S3.1,
  1999).
• Air Force - DODINST 6055.12
• Noise levels within the test booth must be
  measured annually and certified.
• The certification sheet must be placed in plain
  view.
• This is usually performed by an Industrial
  Hygienist, but can
• also be done by an Audiologist or trained
  technician.

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Audiometric Test Booth Maximum Allowable Sound
Pressure Levels
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Audiometric Test Booth

• Ventilation Systems
• Test booths must provide adequate air exchange
  for patient comfort.
• Ventilation systems must not be too noisy.
• Construction of Audiometric Booths
• Walls are made of materials that reduce the
  transmission of sound.
• Do not paint the inside of an audiometric test
  chamber.

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Audiometric Test Booth

• Construction of Audiometric Booths (cont.)
• Reduction of high frequency sounds is greater
  than for low frequency sounds.
• The most common cause of audiometer booth failure
  is low frequency noise.

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Audiometric Test Booth

• Vibration and Audiometric Booths
• Vibration is a source of noise that must be
  controlled.
• Acoustical booths are mounted on vibration
  isolators or shock mounts that reduce or absorb
  the vibrations of surrounding structures.
• Never put an audiometric booth on blocks. To do
  so will eliminate the isolation effect of the
  shock mounts.
• Audiometric Booth Door
• The booth door is equipped with seals that should
  be air-tight.

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Audiometer Calibration
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Audiometer Electro-acoustic Calibration

• CALIBRATION REQUIREMENTS
• Annual, comprehensive electro-acoustical
  calibration.
• Equipment must meet requirements specified in
  ANSI S3.6 1996
• Daily Calibration
• Daily Functional Check

• Audiometers and headphones are calibrated
  together as a unit swapping headphones between
  audiometers is not permitted, as it will affect
  calibration.
• The audiometer must be tagged with a calibration
  sticker that states the date of next calibration.

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TECFICS

• The daily functional check detects hardware
  problems and ensures that the audiometer is
  working properly

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T

• The equipment check
• Audiometer connections
• Monitor on/off switch
• Printer connections

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E

• Earphone check
• Headband tension
• Earphone cushions
• Diaphragms
• Cords

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C

• Connections check
• Jacks connected securely to jack panel of booth

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F

• Frequency (Left ear ONLY)
• Tone is present for each frequency
• The pitch changes
• Non-wavering tone is present

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I
C

• Intensity (Right ear
• ONLY)
• Steady change in loudness

• Cross talk (Both ears)
• Tone is not present in the unused earphone

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S

• Static (Both ears)
• No interruption or static in the tone
• Trouble spots
• Cord connection to earphones
• Cord connection to jack
• Y where earphone cords are joined

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Daily Biological Calibration
Monitors audiometer output levels between annual
electro-acoustic calibration checks. The daily
biologic calibration check is performed each test
day on every audiometer prior to its use. The
DD 2217 Form establishes a legal record verifying
the audiometers functional capability.
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DAILY BIOLOGICAL CALIBRATION

• Listeners
• Human/Artificial Ear
• Requires 2 listeners per audiometer.
• Listeners must have normal hearing.
• Recording Results
• Results recorded on a DD 2217.
• Need a DD 2217 for each listener.
• Baseline is obtained after annual
  electro-acoustic calibration.
• Compare current test with original baseline.
  Results must be within /- 5 dB of original
  baseline (/-10 dB at 6000 Hz ).
• Immediately following electro-acoustic
  calibration, obtain baseline thresholds on a
  primary and alternate listener for each
  audiometer.

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Biologic Calibration

• Audiometer Failure
• 1st listener fails
• 2nd listener passes
• Audiometer passes/Hearing of Primary listener
  changed/Continue to use audiometer
• 1st listener fails
• 2nd listener fails
• Audiometer fails/Audiometer has changed/Remove
  audiometer from service
• 1st listener fails
• 2nd listener fails
• Substitute audiometer fails
• Ambient noise levels may be elevated

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Troubleshooting after the Daily Calibration Check

• Improper earphone placement
• Malfunction of the Artificial Ear (ME 500)
• Malfunction of the audiometer

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Daily Biological Calibration (continued)

• Completion of the DD Form 2217
• Enter audiometer information manufacturer,
  model, serial number, date of last
  electro-acoustic calibration.
• Enter listeners name, SSN or serial number for
  BioJoe, name of test facility and location.
• Date of testing year, month and day, name of
  examiner, check the block indicating whether
  calibration check passes or fails, and enter
  thresholds.
• The first line of threshold results must be the
  baseline results that are tested and entered
  immediately after the annual electro-acoustic
  calibration.

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ELECTRO-ACOUSTIC CALIBRATION

• Must be performed annually.
• Performed when an audiometer fails daily
  calibration.
• Compares and adjusts the output of an audiometer
  to a KNOWN STANDARD sound pressure level.
• ASO 1951 levels based on data collected at the
  Worlds Fair in 1937
• ISO 1964
• ANSI S3.6 1996 (current standard)
• The sound pressure levels used in calibration are
  equal to the average hearing sensitivity of a
  normal hearing young person.

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ELECTRO-ACOUSTIC CALIBRATION

• ARMY/ARMY NATIONAL GUARD
• Tobyhanna Army Depot
• DSN 795-7134 or [phone]
• Calibration performed by trained biomedical
  maintenance staff. On-site visits are rare.
• AIR FORCE
• MERC teams perform annual electro-acoustic
  calibration on-site
• May be done by contractor also
• NAVY
• Equipment Repair Branch, Navy Environmental
  Health Center, Naval Station, Norfolk, VA

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Audiometer Care

• Clean earphone cushions
• Hang headphones on hook to maintain proper
  headband tension
• Replace earphone cushions, cords and hand
  switches as needed
• Do not allow earphones to slap together

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Army Calibration Site Address
Medical Maintenance Operations Division Attn
MCMR-MMM-DP/Mr. Frank Martinsky Warehouse 4, Bay
1 11 Hap Arnold Blvd. Tobyhanna Army Depot, PA
18466-5063 [phone]
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QUESTIONS???
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Practice Time
Daily Functional Listening Check Daily
Biological Calibration