Using the FONIX 7000 to Verify Coupler and Real-Ear Performance ...

Real Ear Measurements 46
3. Comfortable, but Slightly Soft
2. Soft
1. Very Soft
0. Cannot Hear at All
5. Place the probe tube in the ear canal of the test ear so the
tip is 6 mm from the TM and tape the probe tube in place.
6. Position the insert earphone of TDH headset into or onto
the test ear.
7. Present a continuous pure-tone from the audiometer to the
insert earphone or headset @ 500, 1000, 2000, 3000 and
4000 Hz
8. Complete a practice run @ 1000 Hz
9. Use an ascending procedure starting @ 20 dB SL re:
threshold at 1000 Hz.
10. Increase 10 dB until the patient provides a response of
“Uncomfortably loud” (7).
11. Decrease 10 dB and begin to ascend in 5 dB steps
until the patient provides a response of “Loud, but OK” #6.
Then ascend in 5 dB steps until the patient once again provides a response of
“Uncomfortably Loud”
12. Decrease 10 dB and increase 5 dB until patient provides the same LDL for a
loudness judgment of “Loud, but OK” (#6) half the time. This is the LDL for the
test frequency and ear.
13. Repeat at 2000, 3000, 4000 and 500 Hz and then test the opposite ear.
Figure 59 – Probe mic and
insert earphone placement
for measuring LDLs
14. At the first test frequency (1000 Hz), present a 70 dB HL signal. On the monitor,
the clinician should see a value greater than 70 dB SPL. If the value is less than
70 dB SPL, then either the probe is clogged or pinched. The clinician needs to
replace or reposition the probe tube.
15. The difference between the dial reading on the audiometer (70 dB HL) and the
measured SPL seen on the monitor is the REDD (Real-Ear-To-Dial-Difference).
Quickly repeat this measure at 2000, 3000, 4000 and 500 Hz.
16. You can add the REDD to the audiometric threshold at each frequency to convert
audiometric threshold (dB HL) to threshold in dB SPL. This can be a very useful
tool for clinicians who believe in the verification process of assuring that soft
sounds (in dB SPL) are audible (i.e., live speech mapping). Measuring the REDD
and adding these values to the patients audiometric threshold is far more
accurate than entering thresholds into a real ear analyzer and have the software
complete average transformations!