2014 Inner Ear Physiology

Comparing hearing tests

TEST
TECHNIQUE
MEASUREMENT
EVALUATION
  • seal ear canal closed
  • apply known amount of sound energy
  • vary pressure in ear canal and repeat sound presentation
  • middle ear compliance
  • normal:  middle ear pressure = atmospheric air pressure

CONDUCTIVE HEARING LOSS

  • fluid in the middle ear
  • negative middle ear pressure
  • TM perforation
  • ossicular chain disruption
  • patency of ventilation tube
ACOUSTIC REFLEX TEST
  • apply loud sound
  • conduct tympanometry test
  • HL required to evoke acoustic reflex (detected as a decrease in middle ear compliance)
  • middle ear function
  • inner ear and auditory nerve/brainstem function
  • facial nerve function
RINNE
  • apply tuning fork to mastoid to determine bone conduction threshold
  • move fork away to determine air conduction threshold
  • compare air and bone conduction thresholds
  • conductive hearing loss
WEBER
  • apply tuning fork to mastoid to center of head or forehead
  • determine whether sound lateralizes
  • conductive hearing loss
  • sensorineural hearing loss
AUDIOGRAMS      
  • Behavioural
   
  • cochlear function
  • auditory pathway, CNS and motor response pathway
  • insert microphone and speaker into external ear canal
  • play either clicks or a series of tones at varying intensities
  • measure emissions from ear in response to tones
  • middle ear function
  • cochlear (esp. outer hair cell) function
  • apply EEG electrodes to scalp
  • put on earphones
  • vary stimulus intensity and frequency
  • amplitude and latency of EEG waveforms evoked by stimulus
  • middle ear function
  • inner ear and auditory nerve function
  • auditory pathway function
Email: Dr. Janet Fitzakerley | ©2014 University of Minnesota Medical School Duluth | Last modified: 15-feb-14 9:04 PM