Chapter 3: The Human Ear, Hearing Loss, and Pure-Tone Hearing Tests Flashcards
Conductive Mechanism
Outer and Middle ear
Sensory/neural Mechanism
Inner ear, auditory nerve and pathways beyond
Air Conduction
How well sound travels through the outer and middle ear to asses overall degree of hearing loss
Bone Conduction
Bypasses the conductive system (outer and middle ear) to directly stimulate inner ear and asses sensory/neural mechanism
Weber Tuning Fork Test
-A test of perceived tone lateralization.
-Normal or symmetrical hearing loss will hear tone in the midline
-Tone will lateralize to better ear for asymmetric sensory/neural loss and to the poorer ear in conductive hearing loss
Rinne Tuning Fork Test
-A comparison of perceived loudness of an air-conducted signal to a bone-conducted signal
-Normal hearing or sensory/neural hearing loss will hear the tone better by air conduction
-Those with conductive hearing loss will hear better by bone conduction
Three-frequency PTA
-Average of 500, 1000, 2000 Hz
-Useful for predicting the threshold for speech as well as for the degree of communication impact by hearing loss
-Most often conducted
Two-Frequency PTA (Pure tone average)
-Average of the lowest two thresholds at 500, 1000, and 2000 Hz
-Often a better predictor of the threshold for speech especially with steeply sloping audiometric configurations
Variable PTA
-Average of the poorest three thresholds at 500,1000, 2000, 4000 Hz
-More effective than three frequency PTA in regard to degree of communication impact
Air Bone Gap (ABG)
The difference between air-conduction thresholds and bone-conduction thresholds
Cautions in assessing hearing loss
-Tactile responses
-Cross hearing
-Nonorganic hearing loss
Normal Hearing
Normal thresholds in both AC and BC
Conductive Loss
loss of sensitivity in AC thresholds, but not in BC thresholds
Sensory/neural loss
Equal loss of sensitivity in both AC and BC thresholds at a given frequency
Mixed Loss
Loss of sensitivity in both AC and BC thresholds, and an ABG of at least 15 dB
