Ear Testing

Ear Testing

·        Voice Testing

·        Tuning fork tests:

o   Rinne Test: 512 Hz fork beside the ear. If conductive loss then bone conduction is better than air conduction. If sensorineural, air conduction best

o   Weber Test: Tuning fork on top of the head. Louder in affected ear if conductive loss, softer in affected ear if sensory loss

·        Pure Tone Audiometry:

o   Can establish severity of hearing impairment and whether sensorineural or conductive

o   Measures thresholds across a range of frequencies. Threshold = lowest intensity that can be detected

o   Usually only test in range of conversational speech (250 Hz to 8 KHz)

o   Normal hearing is 0 – 20 dB (zero is based on population surveys)

o   Harder if child aged 3 – 5: need to play games etc

·        Auditory Brainstem Response (ABR):

o   Detects evoked potentials in the brainstem in response to sound

o   Used for neonatal testing (reliable from full term), in older kids where behavioural responses are unclear and for testing the auditory nerve (eg acoustic neuroma – but MRI is gold standard, CT with contrast poorer)

·        Tympanomtery:

o   Measures compliance of middle ear

o   Normal is -100 to 100 daPa

o   Type A: normal (peak compliance over 0 daPa).  If peak is low ?scarring or adhesions

o   Type B: Flat curve (ie not compliant at any pressure).

·        Low volume type B: wax impaction or middle ear infusion

·        High volume type B: perforation or grommet

o   Type C: Peak shifted to the left.  Eustachian tube obstruction

·        Otoacoustic emissions:

o   Test for cochlear function, eg in neonatal screening

o   Also for tinnitis: is it cochlear or non-cochlear

·        Paediatric testing:

·         0 – 3 months: referred from neonatal high-risk register.  Need to correct (eg hearing aid implants) by 9 - 10 months otherwise speech impairment

·        6 – 12 months: distraction testing – looking for head turning, etc

·        1 – 2½ years: in a room with speakers