09_Intro to RECD Flashcards
Once we ____ the ear canal, we change the resonant properties of the ear
occlude
Ear canal dB SPL - coupler dB SPL = _____
RECD (dB)
What are the 2 key concepts regarding RECD?
1) It’s referenced to a specific coupler
2) A small earphone-like transducer is used to send sound into the ear (NOT a loudspeaker)
What are the steps for taking an RECD measurement?
- connect foamtip (or earmold) to RECD transducer
- a test signal will be pre-chosen for you
- measure that test signal in the coupler
- place the probe tube
- plate the foam tip or earmold over the probe tube s/ moving it
- measure the same test signal in the ear
- the system’s software will calculate the difference b/w the test box and ear measure in the direction of real ear minus coupler
Does Carl have an average RECD?
No
True or False: average transforms miss 30 dB of variance with RECDs
True
______ + HL audiogram + unique RECD = SPLogram
RETSPL
- this transform process (HL to SPL) is done by the software
Measured transforms are reliable to within ___ to ____ dB across frequencies.
2 - 5 dB
True or False: the size of a person’s RECD has no effect on the calculated SPL thresholds
False - whether a person has a large or small RECD will change the entire SPLogram
True or false: by measuring the RECD and including it, we increase the precision of the threshold definition on the SPLogram
True
Name the basic steps of a normal protocol for assessment through to fitting
- test hearing with insert phones
- measure RECD
- use software-based system that provides an RECD-corrected SPLogram
- select hearing aids and fit them to targets on the SPLogram using speech test signals
Which type of coupler RECD measured with, according to ANSI (2013)?
The HA1 2cc coupler
Can we use an HA2 coupler to measure RECD? Why might we do this?
Yes - the difference between the HA1 and HA2 couplers can be calculated, so we can use HA2.
We might do this to prevent infection control problems that might arise from using HA1 + putty, and because sometime putty won’t stick to earmolds (e.g vinyl)
All VF1 couplers are __ in colour, and the HA1 and HA2 for RECD are both ___ cc
Silver
2 cc
For the VF2, the silver couplers are ___ cc, and used in Speechmap for RECDs
0.4 cc
For the VF2, what is the purpose of the “TRIC adapter”?
A black rubber adapter that replaces the putty and BTE coupler stem
For the VF2, how many cc’s are the blue couplers and what are they used for?
2.0 cc
For ANSI testing ONLY
What colour and size are the Aurical couplers?
Silver
2 cc
How do you connect hearing aids to the HA1 coupler in the Aurical?
Using putty
How do you connect BTE hearing aids in the Aurical?
The BTE stem is removed from the 2cc portion and replaced with a cap to “build” the HA1
Why was the 0.4cc coupler developed? How does this work?
To support more accurate measurement in the extended high frequencies.
It’s lower volume provides a lower noise floor in the extended high frequencies.
Which coupler has a higher SPL: 0.4 cc or 2 cc?
- 4 cc because it has a smaller volume (about 15-20 dB difference)
- VF2 system automatically accounts for this difference
True or False: The RECD will change based on the coupling to the ear and by age.
True
What 3 things are RECD norms currently developed for?
Age (in months) (use corrected age for premies)
Foamtip vs earmold
To 8000 Hz
True or false: corrections for earmold vs foamtip coupling are published and implemented in all systems
False: some, but not all systems
We can use the RECD twice. What for?
1) converting HL thresholds to ear canal SPL for display on SPLogram
2) for predicting the real ear aided response (REAR) from coupler measures of the HA
**originally developed as a pediatric procedure
Fill in the equation to show how we can build the real ear SPLogram from coupler data if we have a measured RECD:
Coupler SPL + RECD + _____ = Real-ear SPL
Microphone location effects (MLE)
Fill in the equation:
___ + RECD + RETSPL = Real ear SPL
HL
Troubleshooting RECD:
What should you check if your RECD low frequency values are too low, compared to norms matched to age and coupling type?
- let foam expand completely
- reseat the earmold and/or use earmold lubricant
- crosscheck impedance and otoscopy results (tubes/vents typically have -10 to -15 dB at 250 Hz) (bigger than 2cc -> negative values)
- check the coupler (0.4cc RECDs are typically negative in the lows, so choose a software mode that lets you see it as a simulated HA1-referenced RECD
Troubleshooting RECD:
What should you do if the high frequency values are too low or have a notch, compared to age and coupling type matched norms?
- the probe tube may be too shallow
Note: earmold RECDs in adults usually roll off after 2k. Very small ears may not show this pattern
Troubleshooting RECD:
What could be the cause of the RECD graph having an odd shape
The person may have been talking during the measurement. Re-try.
