09_Intro to RECD

Question 1

Once we ____ the ear canal, we change the resonant properties of the ear

Answer 1

occlude

Question 2

Ear canal dB SPL - coupler dB SPL = _____

Answer 2

RECD (dB)

Question 3

What are the 2 key concepts regarding RECD?

Answer 3

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)

Question 4

What are the steps for taking an RECD measurement?

Answer 4

• 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

Question 5

Does Carl have an average RECD?

Answer 5

No

Question 6

True or False: average transforms miss 30 dB of variance with RECDs

Answer 6

True

Question 7

______ + HL audiogram + unique RECD = SPLogram

Answer 7

RETSPL

- this transform process (HL to SPL) is done by the software

Question 8

Measured transforms are reliable to within ___ to ____ dB across frequencies.

Answer 8

2 - 5 dB

Question 9

True or False: the size of a person’s RECD has no effect on the calculated SPL thresholds

Answer 9

False - whether a person has a large or small RECD will change the entire SPLogram

Question 10

True or false: by measuring the RECD and including it, we increase the precision of the threshold definition on the SPLogram

Answer 10

True

Question 11

Name the basic steps of a normal protocol for assessment through to fitting

Answer 11

• 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

Question 12

Which type of coupler RECD measured with, according to ANSI (2013)?

Answer 12

The HA1 2cc coupler

Question 13

Can we use an HA2 coupler to measure RECD? Why might we do this?

Answer 13

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)

Question 14

All VF1 couplers are __ in colour, and the HA1 and HA2 for RECD are both ___ cc

Answer 14

Silver

2 cc

Question 15

For the VF2, the silver couplers are ___ cc, and used in Speechmap for RECDs

Answer 15

0.4 cc

Question 16

For the VF2, what is the purpose of the “TRIC adapter”?

Answer 16

A black rubber adapter that replaces the putty and BTE coupler stem

Question 17

For the VF2, how many cc’s are the blue couplers and what are they used for?

Answer 17

2.0 cc

For ANSI testing ONLY

Question 18

What colour and size are the Aurical couplers?

Answer 18

Silver

2 cc

Question 19

How do you connect hearing aids to the HA1 coupler in the Aurical?

Answer 19

Using putty

Question 20

How do you connect BTE hearing aids in the Aurical?

Answer 20

The BTE stem is removed from the 2cc portion and replaced with a cap to “build” the HA1

Question 21

Why was the 0.4cc coupler developed? How does this work?

Answer 21

To support more accurate measurement in the extended high frequencies.
It’s lower volume provides a lower noise floor in the extended high frequencies.

Question 22

Which coupler has a higher SPL: 0.4 cc or 2 cc?

Answer 22

0. 4 cc because it has a smaller volume (about 15-20 dB difference)
   - VF2 system automatically accounts for this difference

Question 23

True or False: The RECD will change based on the coupling to the ear and by age.

Answer 23

True

Question 24

What 3 things are RECD norms currently developed for?

Answer 24

Age (in months) (use corrected age for premies)
Foamtip vs earmold
To 8000 Hz

Question 25

True or false: corrections for earmold vs foamtip coupling are published and implemented in all systems

Answer 25

False: some, but not all systems

Question 26

We can use the RECD twice. What for?

Answer 26

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

Question 27

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

Answer 27

Microphone location effects (MLE)

Question 28

Fill in the equation:

___ + RECD + RETSPL = Real ear SPL

Answer 28

HL

Question 29

Troubleshooting RECD:

What should you check if your RECD low frequency values are too low, compared to norms matched to age and coupling type?

Answer 29

• 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

Question 30

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?

Answer 30

• 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

Question 31

Troubleshooting RECD:

What could be the cause of the RECD graph having an odd shape

Answer 31

The person may have been talking during the measurement. Re-try.