Transcript Instrumentation

CONDUCTIVE
Normal hearing
SENSORINEURAL
Outer ear
Middle ear
Inner ear
Auditory nerve
Outer ear
Middle ear
Inner ear
Auditory nerve
Outer ear
Middle ear
Inner ear
Auditory nerve
Outer ear
Middle ear
Inner ear
Auditory nerve
AC √, BC √
Conductive HL
AC X, BC √
Sensorineural HL
AC X, BC X
Mixed HL
AC X, BC X
Diagnostic tuning fork tests
1.
Schwabach (Dabobert Schwabach, 1846-1920)
2.
Rinne (Heinrich Rinne, 1819-1868)
3.
Bing (Albert Bing, 1844-1922)
4.
Weber (1832-1891)
The Schwabach test

Bone conduction test

Place tuning fork alternatively on mastoid process of patient and
tester

Is sound heard or not?

Results:

Normal Schwabach: Both stop hearing at the same time

Diminished Schwabach: SN hearing loss

Prolonged Schwabach: Conductive hearing loss

False normal Schwabach: Response to better ear, not test ear
The Rinne test

Compare hearing sensitivity with AC to that with BC

Results:

Positive Rinne: Normal hearing or SN hearing loss

Negative Rinne: Conductive hearing loss

False negative Rinne: Non-test ear responds
The Bing test

Based on the ‘occlusion effect’: If hearing is normal, loudness of BC
tone increases when ear canal is closed.

Tuning fork held to mastoid process of patient while ear canal is
alternatively closed and opened by tester.

Results

Positive Bing: Sound alternates in loudness. Normal hearing and
SN hearing loss

Negative Bing: No change in loudness. Conductive hearing loss

False positive Bing
The Weber test (1834)

Based on ‘lateralization’.

Tuning fork placed on the midline of the skull.

Where is the sound heard? Left, Right, Both ears, or midline?

Results

Normal or bilateral symmetrical hearing loss: Midline or in both
ears

Unilateral SN hearing loss: In better ear

Unilateral conductive hearing loss: In poorer ear