Lecture 3 Flashcards
What is pure tone audiometry?
Provides the most basic measure of hearing acuity. Is the threshold of hearing across the frequency range.
Measured in dBHL (hearing level/loss). The point at which a person can just hear a pure tone.
What is the conversion from sound pressure level to hearing level to an audiogram?
dBHL = dBSPL. Sound pressure level means that this is the level that the average person can hear at a certain frequency. Norms have been created to that at any frequency dBHL=0.
dBSPL 11 at 10 micropascals -> dBHL = 0 at 2000Hz
What can pure tones tell us?
The type of hearing loss (CHL, SNHL). Provide quantifiable frequency-specific information about damage to the auditory system.
“Degree”/ “Configuration”
What is bone conduction?
Positioned behind the ear, the BC sends the signal directly to the cochlea. Bypasses the ear canal and middle ear signal.
If AC is bad and BC is good, then something is going on in the ear canal or middle ear; everything past the inner ear is fine.
For bone conduction where do the symbols go for each ear, what is the symbol?
Right ear BC is always on the left of the line, left ear BC is always on the right of the line.
Symbol = >
What is air conduction?
Measures the response of the whole auditory system. Sends signal into the ear canal, middle ear, cochlea to the brain. Can use supra-aurals or inserts.
What is conductive hearing loss?
Difference between the air and bone conducted results - the BC is better than the AC, but BC is in normal range, AC is not normal.
Shows that the cochlea is fine, but there may be hearing loss in the ear canal/air conducted route - something preventing sound from getting to the cochlea.
What is mixed hearing loss?
Air bone gap is greater than 10dB (considered to be a middle ear disorder), bit of both sensorineural and conductive loss. Both AC and BC are abnormal.
What is sensorineural hearing loss?
BC and AC are abnormal (same or within 10dB). Is at the cochlea or beyond.
What is the pure tone average?
What are some issues with this?
PTA - the average of air conducted responses to 500Hz, 1000Hz and 2000Hz. Has diagnostic value, important for what person says they hear vs. actual measurements. Frequencies are important for someone to be able to hear speech (3 averaged).
Issues: Not always a great correlation - your assumption that they can’t hear frequencies vs. what they actually hear (assumption based on PTA).
What are some of the common descriptors for the configuration of hearing loss?
Flat, sloping (down), rising, notched, cookiebite, reverse u-shaped, high frequency (flat, slop down to the right), other.
Also gradually (less steep slope), precipitously (steep slope), sharply.
In general, how do you describe the pure tone results?
Type: conductive, mixed, sensorineural
Degree: mild, moderate severe
Configuration: sharply, precipitously
What are the types of receivers used for pure tone audiometry?
Supra-aural earphone (environmental), insert earphone, bone vibrator, circumaural earphone (more sound proofing), loudspeakers (for children).
What 3 components must the receiver have?
Good frequency range
Good dynamic range
Good stability over time, handling, temperature
Why do HL/SPL conversion values change for each receiver?
Because there are different norms that we hear differently (mastoid/cochlea). Have to create new norms. At 0dBSPL, can hear more quiet sounds if in bone oscillator.
