Final Exam Review Flashcards
What is the Lybarger prescription?
“Half-gain” rule
1944
What is the POGO and POGO II prescription?
POGO (1983) POGO II (1988)
Half-gain + low-frequency correction factor
What is the Berger prescription?
More than half gain for middle frequencies
1979, 1988
What is the Libby prescription?
Gain about 1/3 of the hearing loss
1986
What is the NAL-R prescription?
LTASS placed @ MCL
Intelligibility is assumed to be maximized when all bands of speech are perceived to have the same loudness
1986
What is the NAL-RP prescription?
Change in slope from 46% to 31%
What is the DSL prescription?
Achieve audibility & comfort in each frequency region
What is the Cambridge prescritpion?
Essentially the same rationale as NAL
Which prescriptive method provides the most gain?
From greatest to least amount of gain:
- Berger
- DSL
- POGO
- NAL-R
- Libby
What is the IHAFF/Contour?
IHAFF- Independent Hearing Aid Fitting Form
- IHAFF protocol aims to normalize loudness at each frequency
- Recommends CT of 40-45 dB
What is the FIG6?
- Developed by Killon & Fikret-Pasa (1993)
- Use of average loudness data
- Loudness normalization
What is the DSL [i/o]?
Goal: restore amplification characteristics so all acoustic signals available to WNL listener available to HoH listener within auditory DR
Loudness equalization
What is the DSL 5.0?
Adjustment to gain: lows, mids, highs
- Correction for conductive hearing loss
- Correction for binaural amplification
What is the NAL-NL1 prescritpion?
- Underlying rationale = maximize speech intelligibility (not to restore normal loudness) but with overall loudness of speech at any level being no more than perceived by a listener with normal hearing
Two theoretical models used:
- Speech intelligibility index
- Method for calculating loudness
- Prescribed gain for 70 dB input similar to NAL-RP
What are difficult issues related to selecting a prescription method?
- Acclimatization & adaptation gain & frequency response
- Patients adapt to the tinny sound of the hearing aids and get more benefit
- The more the patient listens with amplification, the more they adapt - Preferred loudness
- Hearing aid users prefer 3-4 dB less than what’s prescribed - Dead regions
- Damage to the inner hair cells; no signal going to the brain
- Sending sound to dead regions results in distortion - Severe hearing loss, effective audibility, & high-frequency amplification
How can you verify hearing aid performance?
- Probe microphone measurements
- Real ear measurements with speakers in front and in back of the patient
Why do you need to verify hearing aid performance?
- For quality control, to make sure they are getting sufficient volume to hear speech
- Also used to counsel the patient
What is the primary goal of orientation?
PHAST (Desjardins & Doherty, 2009)
- Remove your hearing aid
- Open the battery door
- Change the hearing aid battery
- Demonstrate how you clean your hearing aid
- Put your hearing aids in
- Turn up the volume
- How do you use the telephone with your hearing aids
- How do you use the noise program/directional microphone
What are appropriate expectations for new hearing aid users?
Listening in quiet
- We expect patients will hear better in quiet situations
Background noise
- They should hear better in background noise with hearing aids (if it’s a moderate level)
- They will not hear better in an extremely noisy situation
- Their hearing in loud background noise should be no worse than listening without their hearing aids
- They should expect to hear soft speech, average speech should be comfortable, and loud speech should not be uncomfortable
Earmold/earshell comfort
- It should be comfortable to wear for the patient
Own Voice
- They should expect that their own voice is acceptable to them (counsel them on getting used to the occlusion effect)
Acoustic Feedback
- There should be no feedback during regular use
- Not unusual for older patients to put their hearing aids on upside down or on opposite ears
What is the bottom line of the hearing aid fitting?
- Patient understanding of hearing loss consequences and treatment options
- Acknowledgement and “ownership” of hearing loss
- Help to overcome obstacles to better hearing
- Orientation/instruction
- Help patient with other communication strategies
- Provide perceptual training in speech understanding
What does the acronym “BUS” stand for?
B- Benefit
- Make sure that we have decreased the disability
- Want the patients to be able to hear certain things again (speech & environmental sounds)
U- Use
- Want the patient to use their hearing aids in every possible situation where they have trouble hearing
S-Satisfaction
- Want the patient to be satisfied with the selection, fitting, and outcome of their hearing aids
Why is it necessary to validate the fitting?
- Demonstrate benefit
- We can’t determine from an audiogram, occupation, and age, how the patient will do with their hearing aids - Justify cost
- Especially with premium hearing aids
- Any hearing aid will provide measurable benefit (especially in quiet) - Help with patient management
- Reduce return rate
- Demonstrate benefit to the patient
How can the clinician validate the fitting?
Objective
- Limitations
- Doesn’t give a sense of listening in environmental sounds
- Doesn’t take into consideration the self-monitoring of the patient’s voice
- Can’t recreate all listening environments - Benefits
- Direct/objective way to determine how well the patient hears with their hearing aids and without
- Can quantify residual difficulty that they might have - Speech testing in quiet
- Only a moderate correlation between objective measurement of benefit and self-reported measurement of benefit (not 1:1 relationship)
- Fixed presentation level (55 dB)
- Normal low frequency and steeply sloping high frequency hearing loss (40 dB)
- To compare aided to unaided; program 1 and 2; compare monaural to binaural fitting - Speech testing in noise
- HINT vs. Q-SIN
Subjective
- Informal assessment
- Evaluation of self-perceived benefit
- Evaluation of use time
- Evaluation of satisfaction
What is the SSQ?
Speech, Spatial, and Qualities of Hearing
- Short version (12 questions)
- Localization ability
- Spatial awareness
What is the GPHAB?
Gatehouse, 1999
What is the summary of validation?
- Benefit (e.g., APHAB, COSI, HHI-A/E, GPHAB, SSQ)
- Aided Performance (e.g., APHAB, COSI, HHI-A/E, GPHAB, SSQ or speech tests)
- Usage (IOI-HA, GPHAB)
- Problems with hearing aids
- Satisfaction (e.g., an overall rating; if a low rating is given, follow-up with informal questioning or SADL)
What are the challenges of validating patients with high frequency sensorineural hearing loss?
- Difficult to measure objective benefit
- Benefit best measured with COSI
- Ceiling effects for measuring speech in quiet and speech in noise
What are the different kinds of frequency lowering algorithms?
1) Linear frequency compression
- If energy above 2500 Hz is greater than the energy below 2500 Hz, FL occurs
2) Linear frequency transposition
- Audibility extender by Widex
- Continually searches for the most intense spectral peak in a limited frequency range known as the source region
- Determined by a programmable start frequency that is selected between 630-6000 Hz (Ex. if we welect 2000 Hz, energy above that is moved into the target region)
- Target region is one octave below the source region (where the source region is moved to)
- Below the nominal start frequency, there is a potential mixing of energy from the original input signal, the transposed signal from the basic mode, and the transposed signal from the expanded mode
- FL is continuous, but dynamic
- All FL occurs below the start frequency
3) Nonlinear frequency compression
- Sound Recover by Phonak
- Frequency selective and is implemented nonlinearly in the spectral domain across time
- Start frequency is between 1500-6000 Hz
- All frequency lowering occurs above the start frequency
- The compression ratio can vary from 1.5:1 to 4.0:1
4) Spectral envelope warping
- Spectral IQ by Starkey
- Uses a classifier that looks for spectral features in the high frequency spectrum that are characteristics of speech
- The term translation has been used to describe the algorithm behavior as the features are added to the low frequency signal in a way that preserves their natural harmonic structure
What is feedback?
Leakage out of the hearing aid that feeds back into the hearing aid microphone
What is feedback control?
- Reduces or eliminates feedback by changing device settings
- Shifting resonant peak to a lower frequency, adjusting low level gain, and decreasing bandwidth
Disadvantages: gain or the bandwidth is reduced which can affect speech intelligibility
What is feedback cancellation?
- Identifies and eliminates feedback without altering gain or frequency response
- Analyzes feedback path and isolates feedback signal at the hearing aid input so they can subtract and cancel the feedback
- Narrow band notch filters: put a notch in a feedback frequency
- Phase cancellation: when the feedback frequency is detected, the hearing aid produces a signal that is 180 degrees out of phase to cancel the signal
- Is not effective if you have an ill fitting ear mold or inappropriate vent size
What is entrainment?
The sound that the hearing aid produces when the hearing aid hears music or feedback
What is data logging?
- Tells the clinician how many hours a day the patient wore their hearing aids
- Really useful for trouble shooting, reprogramming, and/or hearing aid follow-up
How does the NFMI wireless connection option work?
NFMI (Oticon, Phonak)
- Near field magnetic induction
- 3 to 15 megaHz range
- The hardware is well established and easily used/accessible
- Operates within a frequency band that easily propagates through and around the human head and body
- Limited transmission range
- Requires pairing devices and relay devices remain close to the hearing aids
How does the 2.4 GHz wireless connection option work?
- Resound
- Industrial scientific medical band
- Allows signals to propagate easily through air so there’s less degradation of the signal strength
- Allows long-distance audio streaming (up to 30 feet)
Disadvantage: the high-frequency nature results in a short wavelength that does not propagate well through and around the head; poor connection between both ears
How does the 900 MHz wireless connection work?
Starkey
- Industrial scientific medical band
- Allows for long distance wireless programming
- Ear to ear binaural processing without an inter-medical device
- Will propagate through and around the body
- Only stand alone option for far field wireless transmission and reliable ear to ear communication
If the patient has trouble changing their battery, what should the clinician do?
Cause: using wrong size or inserting incorrectly
Solution: re-instruction
If the patient has trouble operating controls, what should the clinician do?
Cause: poor understanding, insufficient instruction
Solution: re-instruction, add a remote control
If the patient complains of discomfort, what should the clinician do?
Cause: ear mold too big/small, tubing receiver too long/short
Solution: remake, change length
If the patient complains of poor retention, what should the clinician do?
Cause: wrong size ear mold or dome
Solution: increase/decrease size, add canal-lok, add retention wire
If the patient complains of their own voice quality, what should the clinician do?
Cause: occlusion (hollow, barrel-sound), too loud, too soft (muffled)
Solution: increase venting, increase compression, decrease compression
If the patient complains of feedback, what should the clinician do?
Cause: ear mold or dome inserted incorrectly, poor fit, feedback manager needs to be calibrated or turned off (depending on when feedback occurs), cerumen in sound path, too much venting
Solutions: re-instruction, re-make or re-size dome, feedback manager calibration or turn off FB manager, cerumen management, decrease vent size
If the patient complains of sound quality, what should the clinician do?
Cause: too tinny, too loud
Solutions: counsel about acclimatization, turn on adaptation manager
If the patient’s hearing aids are weak, what is the cause and solution to the problem?
Cause:
- Weak battery
- Clogged sound bore or receiver
- Clogged microphone inlet port or faulty microphone
Solution:
- Replace battery
- Clear receiver/replace wax guard
- Replace receiver
- Clear microphone port
If the patient’s hearing aid(s) is dead, what is the cause and solution to the problem?
Cause:
- Dead battery
- Clogged sound bore or receiver
- Clogged microphone inlet port or faulty microphone
Solution:
- Replace battery
- Replace receiver
- Replace microphone
If the patient’s hearing aid(s) is distorted, what is the cause and solution to the problem?
Cause:
- Weak battery
- Dirty battery contacts
- Faulty transducer or amplifier
Solution:
- Replace battery
- Clean battery contacts
- Replace transducer
If the patient’s hearing aid(s) is noisy, what is the cause and solution to the problem?
Cause:
- Faulty volume control or tone control
- Interference from electronic devices
- Hearing aid in telecoil mode
- Dirty battery contacts
- Faulty transducer
Solution:
- Clean battery contacts
- Clean volume control
If the patient’s hearing aid(s) is experiencing feedback, what is the the cause and solution to the problem?
Cause:
- Improper insertion
- Poor fit
- Vent plug has fallen out
- Microphone out of place (internal FB)
- Receiving tubing detached from receiver
- Split in earhook or tubing
Solution:
- Rule out cerumen
- Decrease venting
- Remake earmold or refit dome
- Rule out microphone out of place
