Hearing Aid Selection Flashcards
What categories (4) have been successful to consider when selecting a HA for a pt
- Otologic Findings
- Cosmetic Concerns
- Perfomance Criteria
- Financial Consideration
Features of BTE HA’s
- Can be fit to any degree of HL (Mild-Profound)
- Usually fit with a custom mold
- Pt controls options (MTO, VC, and Multiple Memory Switches)
- A connection for Direct Audio Input (DAI) for accepting the input from a whole family of Assistive Listening Devices and Bluetooth short range wireless products
- Some have a switch that will select which mics are active in Multiple Microphone (directional)devices
Features of an Open Fitting HA
- Resembles a BTE but is a whole different generation of device
- Most use a 312 or a 10 size battery due to the decrease in size from a traditional BTE
- Decreases the problem of occlusion due to not having to use the earmold on Open Fit HA’s
- Due to advances in Feedback Management, non custom earbuds are able to deliver sufficient levels of gain to the individual
- MTO are usually not an option on Open Fit HA’s due to smaller size but Directional Mics are an option
- Can fit a wide variety of HL but with more severe HL’s acoustical Feedback may limit the severity served by Open Fit HA’s
Features of ITE (in the ear) HA’s
- Largest of the custom HA family and have been available since the 70’s
- Constructed from an ear impression of the external ear canal, concha bowl and helix
- usually can yield switch for VC, T-Coil switch that can be wired (loop) assistive Listening systems, Multiple Memory switches and Direction Microphone, and DAI
- Usually use a 13 or a 312 battery
- Can be used for most mild, moderate and severe HL’s and may be considered for Profound if proper technique is used in the molding and construction process.
Features of an ITC Hearing Aid
- Smaller version of the ITE
- usually surfaced with the opening of canal and is positioned to fill the complete canal opening
- Usually a 312 battery except for very small ears or when Directional mics are employed then size 10
- VC notch is usually included on faceplate
- Can have other options like DAI and MTO switch IF the ear is big enough
- Usually limited to 1 or 2 options due to its size
- Applicable for mild, and moderate HL
- Severe and Profound may work if proper technique is used to minimize acoustical feedback
Features of a CIC Hearing Aid
- Smaller version of the ITC
- Faceplate usually is recessed several millimeters into the opening of the canal
- Usually yields a 10 battery
- Patient controls are limited due to size
- Applicable for mild and moderate HL’s
- Severe and Profound can be successful in some cases if proper techniques is used to minimize acoustical feedback
If a patients has cosmetic concerns where they do not want the HA to be visible, what HA’s would be best for this pt, assuming the audiological considerations are not a contraindication.
ITC or a CIC
If the pt has no cosmetic concerns what HA’s can be suggested and why
ITE or BTE because it will allow the choice of more options, are easier to fit, require less preventative maintenance and have power cells that last longer
What does DI stand for and what is it
Directionality Index- The ability of the instruments to focus on sounds at 0 degrees (straight ahead) while rejecting those of angles of 90 degrees (sides) and 270 degrees (back)
The greater the DI the more noise that is rejected from angles not directly in front of the client
What does SNR stand for and what does it mean?
Signal to Noise Ratio-
- Measured in dB
- Signal is what the pt wants to hear and Signal is everything else
- Can help to determine if Directional mics are needed
Functional gain testing with CIC instrument is
Simple for the pt to understand with less test-retest variability than conventional sound field testing
With real ear measurement testing, what is true
The probe should be within 5mm of the Ear drum in order to avoid standing waves
The deeper microphone placement offers what advantage
Natural high frequency emphasis between 2700-4000 Hz
The deeper receiver placement offers what advantage
Increased headroom with undistorted output
CIC’s offer a reduction in feedback for ALL of the following reasons.
less venting is required with CIC’s
CIC’s are more tightly fitting
Less gain is required
The occlusion effect is due to
Increase in bone conduction sound for frequencies below 2000 Hz
All of the follow are considered possible disadvantages of CIC fittings
Lack of volume control
Cost
Higher return rate
Earmold impressions for CICs should
Extend at least 2mm beyond the second bend using medium viscosity, silicon material
With CIC fittings, what frequency modifications should be made
Less high frequency amplification should be provided due to the deeper microphone placement
What applies to SIE-O fitted HA
The occlusion effect is minimized
The speaker uses a soft silicone dome or molded, vented acrylic tip to secure the speaker in the ear canal
Allows for more gain than does a SIA instrument
What is a comparison between the SIE-O and SIE-S HA
The SIE-S provides greater acoustic advantages than does the SIE-O
SIA HA’s are designed primarily to
Reduce occlusion and the occlusion effect
SIA Open fit hearing aid applicable gains, without feedback cancellation, shows that the maximum stable gain before feedback to be close to
20dB
The vent as a two channel device, is identified with
Any fit or vented HA
Small diameter tubing of SIA HA’s has the effect of
Reducing the high frequency gain
With SIE-S HA
The only signal is from the HA and phase effects from a vent are not an issue
Evidence suggests that the practical, maximum stable high frequency gain of an open fit device, when feedback cancellation is activated, is closest to
35dB
Performance verification of SIA, SIE-O, and SIE-S HA fitting is best made by
Real ear probe microphone measurements
What is not an advantage of both the SIA and SIE HA fittings
Emphasis on earmold mechanics rather than on electroacoustical
