WinCHAP User’s Manual The DSL/NAL-NL1 Module 67
The DSL and NAL methods for performing RECD measurements are slightly
different. DSL recommends performing all RECD measurements using an HA-2
coupler, even when fitting a canal-type aid that would normally be tested with
an HA-1 coupler; DSL automatically compensates for the acoustical difference
between the couplers.
NAL recommends performing the RECD measurement using the coupler that
will be later used for performing coupler measurements. That is, when fitting a
BTE aid, use an HA-2 coupler for the RECD. When fitting a canal aid such as an
ITE, ITC, or CIC, use an HA-1 coupler. Unlike DSL, NAL doesn’t compensate for
the difference between the HA-1 and HA-2 couplers.
FP40 and 6500-CX Analyzer
The coupler measurement part of the RECD is taken with a 50 Ohm insert ear
-
phone plugged into the external speaker jack of the FP40 or 6500 hearing aid
analyzer. Once this measurement has been taken, it will automatically be used
for all future RECD measurements, even those taken with different clients.
1. Connect the insert earphone to the appropriate coupler. There are several
different possible methods. Use the method most appropriate for your fit
-
ting.
• BTE without custom mold available and ITE/Canal per DSL specs:
Connect the insert earphone directly to the ear level adapter on an
HA-2 coupler.
• BTE with custom mold: Connect the insert earphone to the patient’s
custom ear mold, and use putty to connect the ear mold to the HA-1
coupler.
• ITE/Canal per NAL specs: Connect the insert earphone to an HA-1
coupler using a foam ear tip and Fun Tak.
2. Thread a probe tube through the probe calibration adapter. The tip of the
probe tube should extend no more than three millimeters past the non-
ridged end of the adapter. Fix the probe tube in place at its entry point,
with a bit of Fun-Tak. See Figure 6.2.4.1A.
3. Push the probe calibration adapter into the coupler.
4. Plug the insert earphone into the external speaker jack on the back of the
analyzer.
5. Click Get RECD in the Audiometry window. This will open the RECD
measurement window. See Figure 6.2.4.1B.
6. Select
Coupler.
7. Select the source level by using the arrow buttons located to the left of
the Coupler button. The default level of 70 dB SPL is recommended.
8. Click Start Test. The coupler measurement will be performed.
