Hearing Evaluation

Purpose of the testing is to determine if there is a hearing loss present and to establish the type, degree (severity) and configuration of the loss.   Our center standardly performs the following tests… 

• Pure-tone audiometry is completed in a soundproof booth- a room with special treatment to the walls, ceiling, and floor to ensure that background noise does not affect test results. Only those sounds that the audiologist introduces into the room, either through earphones or through speakers located in the room, will be heard. Sounds may also be sent through a special headset "vibrator" that has been placed just behind the ear or on the forehead.
  
  

  The pure tone test is utilized to find the faintest tones a person can hear at selected pitches (frequencies) from low to high. The test is performed with the patient wearing earphones; insert earphones, or a bone transducer (a small vibrator that is placed upon the temporal bone behind the ear).  The bone transducer "by-passes" outer / middle ear blockages (wax, middle ear fluid, etc.) and tests the auditory nerve by vibrating the skull bones.  By comparing the results from the earphones versus the bone transducer, the audiologist is able to determine if the hearing loss identified is sensorineural ("nerve type hearing loss") or conductive (outer or middle ear pathology).  

  
  

  The result of pure tone testing is an audiogram. The audiogram is a chart that graphically represents a patients hearing sensitivity by plotting frequency (tone pitch) and intensity (loudness) on the two axes. Note the example below: results are interpreted in conjunction with other threshold measures. 

• Speech audiometry includes determining speech reception threshold (SRT) and testing of word recognition. Speech reception threshold testing determines the faintest level at which a person can hear and correctly repeat easy-to-distinguish two-syllable (spondaic) words.  A separate SRT is determined for each ear. 
  
  

  Tests of word recognition attempt to evaluate how well a person can distinguish words at a comfortable loudness level.  The individual being tested repeats words (or points to pictures). The percentage of words correctly repeated is recorded for each ear.  

  
  

  A PIPB test is performed at a level significantly above the previous level utilized for word recognition testing. This open set of monosyllabic words is presented at an elevated level and the score is compared back to that of the previous word recognition test. If a decline of 20% or greater is noted, the PIPB evaluation is considered abnormal (suggests "rollover"). This would suggest that additional diagnostic testing might be required to rule out retrocochlear pathology.

• Acoustic Immittance is performed to determine the status of the tympanic membrane and middle ear via tympanometry. The secondary purpose of this test is to evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem. This test does not directly assess auditory sensitivity, although results are interpreted in conjunction with other threshold measures.  
  
  • Tympanometry measures sound reflection from the tympanic membrane, while the operator varies air pressure in the ear canal. Tympanometry aids assessment of     the outer and middle ear system, including the Eustachian tube.
  • Acoustic Reflex Threshold is a middle ear measurement of stapedius muscle response to higher intensity and adequate duration sounds for individual frequencies.
  • Acoustic reflex decay test assesses the integrity of CN VIII. A contralateral continuous tone is presented for 10 seconds at a stimulus level 10 dB above the   acoustic reflex threshold for that stimulus frequency in that ear.