Amplification Flashcards
Auditory characteristic
At least 500Hz & 2kHz
4kHz expected to be determined early on in the fitting or ideally at the initial diagnostic process
Purpose of RECD
- To determine the individual acoustic transform for use with the DSL method
- To obtain SPL thresholds which is used to generate the appropriate gain & output response in a hearing instrument
RECD measurement
- Must measure baby’s RECD (if feasible)
- Obtained from SpeechMap DSL
- Coupling type should be the same (i.e. for hearing threshold measurement & RECD measurement)
4.
When to use age-appropriate predicted RECD values? If RECD measurement only done on one ear… what value to use for the other ear?
- Only in the event that individual RECD measurement cannot be obtained
- Use measured value from the obtained ear rather than age-related predicted values
Coupler targets should include
- Amplified LTASS across all freq.
2. MPO across all freq.
What to do when a new ear mould impressions is done
A new RECD measurement to include in the calculation of prescriptive targets.
Electroacoustic verification on baby and one thing must do with this method
Done using baby’s RECD, check HA is able to meet the gain and maximum output and fine tune them (Predicting the real-ear performance).
Must check for FB once it has been placed on the baby’s ear. FB manager application should be implemented at every fitting appt.
Directional mic. on or off when verifying?
Shouldn’t be activated when verifying HA for quiet listening environments
Generally to increase SNR, FM system is considered than directional mic use.
Automatic FB suppression
- Should be the last resort.
- Other strategies e.g. good ear mould fit, use of lubricant should be attempted prior to applying FB suppression strategies.
- FB application should be reassessed whoever new ear mould are obtained and should be turned off when not required
Verification stimuli
- To determine audibility and compression characteristics, HA should be verified at various input levels (soft, med, loud speech)
- Verification of speech targets should be completed uing stimuli approximating speech as closely as possible
- Maximum output characteristics for most hearing instuments must be verified using narrowband stimuli.
- For aids that use multichannel broadband output limiting, use a loud speech stimulus (80dB SPL ) and ensure the peaks fo speech fall at or below the upper limits of comfort
REMS priority in babies and young children
- Close match to Average targets & MPO
- Soft & Loud
* *NO compromise should be made to good match for soft and loud
If you made adjustments for soft and loud inputs, should you re-run average and loud ?? Why?
Yes, because that would affect the gain for average and MPO
FM/RM verification
- Verify HA (EHA65SPL) without the FM receiver attached
- Attach FM receiver to HA
- Set FM receiver to manufacturer’s default setting (FM transmitter should be turned ON and set on mute)
- Compare EHA65SPL with RM receiver on & off to determine if there are impedance or program changes to the HA response w/ FM receiver attached
- With HA attached to the 2cc coupler and test mic, place the HA outside of the test box at least 30 cm away from the FM transmitter (FM transmitter in the test box with omnidirectional setting)
5.
Non electroacoustic features
- Binaural (unless SSD)
- BTE (unless contraindicated) or Body worn for multiple disabilities, poor head control or sev-prf losses
- Mould: soft silicone for retention, comfort, safety and FB. Frequent replacement should be undertaken to reduce feedback due to fast ear growth)
- Vent- not feasible due to small size. But sometimes 1mm (no acoustical function but there to keep the ear aerated to avoid moisture build-up)
- Indicator light
- Volume control lock
- Paediatric tone hook- for retention and for smoother speech response
- Tamper-proof battery door
- Open fit avoided due to reduced robustness with thin tube
Electroacoustic features
- Ability to turn off adaptive features such as noise reduction, directional microphones
- Phase cancelling FB system
- Data logging
- DSLv5 prescriptive targets which should include LTASS & MPO targets across all freq.
- FM compatibility
- Speech enhancer
