Behavioral Ax Flashcards
Two ways we can quantify the sound in Behavioral
Assessment,
- Volunteer the sound
- Objective audiometry
Gold standard is the
Behavioral ax
Why do we want to do PTA?
- Estimate degree of handicap
- Get baseline measure of hearing
- Monitor changes in hearing
- For screening hearing loss
- For determining candidacy for a hearing aid or a cochlear implant
- For selecting the frequency-gain characteristics of a hearing aid.
Human hearing range
20-20,000 Hz
Hearing is sensitive to speech sounds @
250-8000Hz
lowest, faintest, softest intensity that the person can hear/detect /discern
Thresholds
air conduction, degree of your hearing, if may normal, mild, moderate, profound; only test by AC
SCREENING
gagamit ng iba’t ibang transducer and we’re able to assess the outer, middle, and inner ear, asl well as the neural components gagamit ng iba’t ibang transducer and we’re able to assess the outer, middle, and inner ear, asl well as the neural components
DIAGNOSTIC
○ Simple signal
○ Standard frequency, phase, amplitude, and duration
PURE TONE
○ vary in frequency over a range that is within a few percent of the nominal frequency
Warble tone
Noticeable to the ear as a noise of distinguishable pitch, and which represents a dominant feature of the total source noise
Narrow band
Transducers
- Supra aural
- Circumaural
- Inserts
- Speakers
- Bone vibrators
○ Widely available
○ Ease of calibration
Surpra-aural
Better seal
Circumaural
○ Better interaural attenuation
○ Better test-retest at 6-8KHz
○ Better for collapsing canal
inserts
XXX for perforated ear
Inserts
Free field→ azimuth
Not ear specific
Speakers
○ Placed behind the mastoid process - Pwede ilagay sa forehead
○ Has a lower sound output limit as compared with AC transducers (60-70 dB)
Bone Vibrator
● Higher maximum output For patients with ear infection
● Lower interaural attenuation May feel heavy for the patient
● Higher interaural attenuation
AC audiometry
● For collapsing ear canals
● For patients with small head
● Lower interaural attenuation
● May feel heavy for the patient
● More expensive because of foam tip replacements
● Not reliable with eardrum perforations
AC audiometry
● Bypasses the outer ear and the middle ear
● Directly stimulates the inner ear (cochlea)
● Used to measure the function of the cochlea or the
“sensory” function
Bone Conduction Audiometry
● Better for the concentration of the tester
● Less cues available for the patient
Two room set-up
Better for patients that need constant feedback or reassurance
For patients that need constant supervision during testing
One room set up
Start at intensity that patient will most recognize well
Familiarization method
More likely that patient has residual
hearing at 1000Hz compared to other frequencies
Start with 0 hz
○ For familiarization
○ If the patient says hearing is equal on both ears, start with the right ear
Test better ear
○ Duration: 1-2 seconds
○ Warble tone: for patients with tinnitus, and for children
○ Narrowband: Ideal for HA and CI aided testing
Stimulus tone
Get inter-octave thresholds if there is a difference of
20dB or between octaves
Frequency hierarchy in PTA
1000Hz →2000Hz →4000Hz →8000Hz →500Hz →250Hz →Recheck 1KHz
Present tone at 40dB! If there is a Response:
decrease level by 10dB
Present tone at 40dB, if no response:
increase level by 20dB. If 90dB, increase by 10dB.
Determining threshold
level at which responses were obtained at two ascending runs (50%)
Both AC and BC are 25 dB or better across all freq
Normal
Only BC is within normal range across all freq
Conductive
Both AC and BC are abnormal but gap is <10
dB
Sensorineural
Both AC and BC are abnormal and gap is >15 dB
Mixed
25 dB or better
Normal
26dB - 40 dB
Mild
41 dB - 60 dB
Moderate
61 dB - 80 dB
Severe
81 dB or greater
Profound
