Exam 2: Dials and Tymps

Question 1

Parts of an audiometer: Oscillator and frequency selector

Answer 1

• internal component you will never actually see
• generates pure tones in varying frequencies: 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000 amd 8000 hz
• some audiometers allow for higher frequency testing
• you control the audiometer with the frequency selector (usually a dial on the front panel)

Question 2

Parts of an audiometer: what frequencies does the oscillator most often generate?

Answer 2

-125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000 amd 8000 hz

Question 3

Parts of an audiometer: intensity or attenuator dial

Answer 3

• controls the loudness of the signal being presented

- moves in 5db steps from -10 dBHL to 120 dBHL for most frequencies, less for lowest and highest frequencies

Question 4

Parts of an audiometer: presentation switch

Answer 4

• allows us to present the signal to the patient

- some people refer to this as the interruptor switch

Question 5

Parts of an audiometer: input signal selector

Answer 5

• allows us to choose what type of signal we want to present

- pure tone, warble tone, pulsating tone, speech, noise, live or recorded speech

Question 6

Tympanometry: basics, what they tell us

Answer 6

• Tymps measure the efficiency of energy flow from the middle ear system as air pressure is varied in the external ear canal
• the resulting data of this pressure change is called a tympanogram and can tell us the following:
• ear canal volume
• static admittance (height)
  
  • peak pressure
• this data allows us to fully describe the tympanogram

Question 7

Tympanometry: Equivalent Ear Canal Volume

Answer 7

• tells us the size of the patients’ ear canal
• normal for adults = 1.0 ml to 2.5 ml
• normal for preschoolers = 0.5 ml
• too low a volume indicates occlusion in ear canal or tester error, artifact i.e. a probe tip facing canal wall instead of the tymp membrane
• large canal can indicate a perforated tymp membrane or tubes in tymp membrane

Question 8

Tympanometry: Peak Pressure

Answer 8

• an estimate of the air pressure at which admittance is maximum
• normal peak pressure = 0 DaPa
• negative Peak Pressure usually indicates some degree of eustachian tube dysfunction, and can be a precursor to (or result of) otitis media

Question 9

Tymp Types: Type A (features, indications)

Answer 9

• normal middle ear pressure
• normal eardrum movement
• normal ear canal volume
• –indicate normal middle ear

Question 10

Tymp Types: Type B (features, indications)

Answer 10

• ”flat”
• no compliance or pressure peak indicated
• NORMAL ear canal volume
• –indicate middle ear fluid

Question 11

Tymp Types: Type B w/ abnormally large ear canal volume (features, indications)

Answer 11

• ”flat”
• no compliance or pressure peak indicated
• INCREASED ear canal volume
• –indicates perforated tymp membrane
• –indicates patent (unoccluded) PE tubes

Question 12

Tymp Types: Type C (features, indications)

Answer 12

• excessive negative middle-ear pressure (peak is towards left)
• normal or reduced compliance
• normal canal volume
• –indicates eustachian tube dysfunction
• –initiation or resolution of middle-ear fluid

Question 13

Tymp Types: Type As (features, indications)

Answer 13

• reduced compliance (shallow peak)
• normal middle-ear pressure
• normal ear canal volume
• –indications:
• –fixation of ossicles
• –scarring on Tymp Membrane
• –this MOVEMENT is sometimes seen in otosclerosis

Question 14

Tymp Types: Type Ad (features, indications)

Answer 14

(described as “flaccid”)

• increased compliance (big peak)
• normal middle-ear pressure
• normal ear canal volume
• –indicates disarticulation of ossicles