ADVANCED AUDIOLOGY EXAM: A+ GRADED GUIDE WITH THE
LATEST KEY QUESTIONS AND ANSWERS.
Air Conduction Threshold Measurement
-Pure tone threshold 250-8000 HZ
-Provides information about severity of loss and configuration, NOT TYPE
-Tests the entire auditory system: Outer, Middle, Inner
Threshold
-The minimum effective sound pressure level of the signal that is capable of evoking an
auditory sensation.
-More than 20 dB difference between threshold frequencies, measured in inter-octive
frequencies (750, 1500, 3000)
Air Conduction Thransducers
-How sound is given to an individual
-Insert earphones: Better inter-aural attenuation (less opportunity for sound to be heard
from other ear), prevents collapsing ear canals, reduces occlusion effect, blocks env.
noise better, more comfortable,
-Circum-aural (supra-aural) headphones: over and around the ears.
-Soundfield speakers (test booth): used with very young children or persons with
developmental disabilities who won't tolerate headphones, must use warble pure tones
or narrow band noise...AVOID standing waves
Headphone/Earphone placement
-Always placed by clinician
-Supra-aural: earphone directly over ear canal opening
-Insert: as deep as possible, pull ear up and back
-Red = Right, Blue = Left
-Begin testing ear with better hearing (as reported by patient or previous test result)
Threshold Bracketing Technique
-Behavioral Audiometry
1. Familiarization Trial: Present signal at 30 dB HL (1000 HZ frequency)
-If patient responds begin threshold search
,-No Response: Increase level to 50 dB HL, then in 10 dB increments until patient
responds-then threshold search
-Still no response = sign of HL
2. OR....place tone continuously on and raise the level until the patient responds.
Threshold Search
-10 dB BELOW the level at which the patient responded during familiarization trial.
-Each time patient responds, decrease by 10 dB (down 10)
-No Response: up 5 dB
-Threshold: Lowest level at which patient responds to the tone 50% of the the time with
at least 3 RESPONSES.
-Example: Familiarization Trial
-Patient responds to 1000 Hz tone at 50 dB HL
-Starting Level? 40 dB HL
-No response: up 5 (45 dB HL) +
-Patient responds: down 10 (35 dB HL)
-No response: up 5 (40 dB HL)
-No response: up 5 (45 dB HL) +
-Patient Responds: down 10 (35)
-No response: up 5 (40)
- No response: up 5 (45)...response! +
Bone Conduction Audiometry
-Used to diagnose type of hearing loss (conductive sensorineural, mixed)
-Bypass the outer and middle ear
-Evaluates the integrity of the inner ear system cochlea and auditory nerve.
-Hearing: Sound transmitted by vibrations of bones in skull, hear own voice, triggered by
air conducted sound that are intense enough to set skull bones into vibration, OR direct
vibration with a TRANSDUCER...tuning fork, bone conduction oscillator.
1. Bone conduction oscillator is placed on the head (mastoid or forehead)
2. Threshold measured at 250, 500, 1000, 2000, and 4000 Hz
3. Bracketing procedure, same as for air conduction measurement (down 10, up 5)
4. Air thresholds and bone thresholds are compared to determine type of hearing loss
, Oscillator Placement
-Mastoid: Most Common
--Issues: people think that is the ear being tested, more sensitive to vibrotactile
stimulation behind the ear than the forehead
-Forehead:
--Issues: Lower maximum output (dynamic range) for bone conduction testing (requires
10 dB more forct ot drive oscillator at forehead), calibration of oscillator usually done for
mastoid.
When are bone conduction thresholds measured?
-Whenever air conduction thresholds indicate hearing loss (>15 dB HL) and/or when
middle ear evaluation indicates middle ear pathology
-Example: Bone conduction= 0, Air conduction = 15-20 dB
Sensorineural HL
-No significant air/bone gap
-When BC threshold is abnormal and within 10 dB of AC threshold
-HL due to problem in the inner ear
Mixed HL
-ABG: AC=50, BC=35
-ABG, but BC thresholds are abnormal
-HL due to problem of inner ear and problem in outer and/or middle ear.
Conductive HL
-ABG >10 dB
-BC threshold is better than AC
-AC=50 BC=10
-HL due to problem in the outer and /or middle ear, but inner ear is normal
Limitations of Bone Conduction testing
-Need to mask to obtain bone conduction thresholds for each ear
-Maximum output is limited: takes more energy to drive the bone conduction oscillator
-Cannot determine the diff. between SNHL and mixed HL when air conduction
thresholds exceed 75-80 dB HL
LATEST KEY QUESTIONS AND ANSWERS.
Air Conduction Threshold Measurement
-Pure tone threshold 250-8000 HZ
-Provides information about severity of loss and configuration, NOT TYPE
-Tests the entire auditory system: Outer, Middle, Inner
Threshold
-The minimum effective sound pressure level of the signal that is capable of evoking an
auditory sensation.
-More than 20 dB difference between threshold frequencies, measured in inter-octive
frequencies (750, 1500, 3000)
Air Conduction Thransducers
-How sound is given to an individual
-Insert earphones: Better inter-aural attenuation (less opportunity for sound to be heard
from other ear), prevents collapsing ear canals, reduces occlusion effect, blocks env.
noise better, more comfortable,
-Circum-aural (supra-aural) headphones: over and around the ears.
-Soundfield speakers (test booth): used with very young children or persons with
developmental disabilities who won't tolerate headphones, must use warble pure tones
or narrow band noise...AVOID standing waves
Headphone/Earphone placement
-Always placed by clinician
-Supra-aural: earphone directly over ear canal opening
-Insert: as deep as possible, pull ear up and back
-Red = Right, Blue = Left
-Begin testing ear with better hearing (as reported by patient or previous test result)
Threshold Bracketing Technique
-Behavioral Audiometry
1. Familiarization Trial: Present signal at 30 dB HL (1000 HZ frequency)
-If patient responds begin threshold search
,-No Response: Increase level to 50 dB HL, then in 10 dB increments until patient
responds-then threshold search
-Still no response = sign of HL
2. OR....place tone continuously on and raise the level until the patient responds.
Threshold Search
-10 dB BELOW the level at which the patient responded during familiarization trial.
-Each time patient responds, decrease by 10 dB (down 10)
-No Response: up 5 dB
-Threshold: Lowest level at which patient responds to the tone 50% of the the time with
at least 3 RESPONSES.
-Example: Familiarization Trial
-Patient responds to 1000 Hz tone at 50 dB HL
-Starting Level? 40 dB HL
-No response: up 5 (45 dB HL) +
-Patient responds: down 10 (35 dB HL)
-No response: up 5 (40 dB HL)
-No response: up 5 (45 dB HL) +
-Patient Responds: down 10 (35)
-No response: up 5 (40)
- No response: up 5 (45)...response! +
Bone Conduction Audiometry
-Used to diagnose type of hearing loss (conductive sensorineural, mixed)
-Bypass the outer and middle ear
-Evaluates the integrity of the inner ear system cochlea and auditory nerve.
-Hearing: Sound transmitted by vibrations of bones in skull, hear own voice, triggered by
air conducted sound that are intense enough to set skull bones into vibration, OR direct
vibration with a TRANSDUCER...tuning fork, bone conduction oscillator.
1. Bone conduction oscillator is placed on the head (mastoid or forehead)
2. Threshold measured at 250, 500, 1000, 2000, and 4000 Hz
3. Bracketing procedure, same as for air conduction measurement (down 10, up 5)
4. Air thresholds and bone thresholds are compared to determine type of hearing loss
, Oscillator Placement
-Mastoid: Most Common
--Issues: people think that is the ear being tested, more sensitive to vibrotactile
stimulation behind the ear than the forehead
-Forehead:
--Issues: Lower maximum output (dynamic range) for bone conduction testing (requires
10 dB more forct ot drive oscillator at forehead), calibration of oscillator usually done for
mastoid.
When are bone conduction thresholds measured?
-Whenever air conduction thresholds indicate hearing loss (>15 dB HL) and/or when
middle ear evaluation indicates middle ear pathology
-Example: Bone conduction= 0, Air conduction = 15-20 dB
Sensorineural HL
-No significant air/bone gap
-When BC threshold is abnormal and within 10 dB of AC threshold
-HL due to problem in the inner ear
Mixed HL
-ABG: AC=50, BC=35
-ABG, but BC thresholds are abnormal
-HL due to problem of inner ear and problem in outer and/or middle ear.
Conductive HL
-ABG >10 dB
-BC threshold is better than AC
-AC=50 BC=10
-HL due to problem in the outer and /or middle ear, but inner ear is normal
Limitations of Bone Conduction testing
-Need to mask to obtain bone conduction thresholds for each ear
-Maximum output is limited: takes more energy to drive the bone conduction oscillator
-Cannot determine the diff. between SNHL and mixed HL when air conduction
thresholds exceed 75-80 dB HL
