1、MEASURING THRESHOLDS DIRECTLY IN dB SPL (AURICAL)The Aurical Audiometry module has the unique capability to directly measure hearing thresholds in dB SPL as opposed to dB HL. This is useful as it avoids the necessity of measuring an RECD to transform thresholds from HL to SPL and is particularly use
2、ful when setting hearing aids*. However, if you have a younger child who will not sit still long enough for you to perform probe microphone measurements in-situ (in front of the loudspeaker) you will still need to measure a RECD to enable hearing aid verification in the coupler. To measure threshold
3、s directly in dB SPL you will need the following transducer headset:Figure 1. Standard SPL probe headset.This Madsen REM/SPL combination insert phone and probe microphone headset is supplied as standard. One disadvantage of using the above probe tip is that audiometry must be carried out using the s
4、upplied coloured eartips rather than a custom earmould. As you are primarily performing audiometry to accurately set up the hearing aid less errors will occur if you use the custom earmould. The following has been proposed to allow you to use the custom earmould for audiometry. If you would like to
5、continue to use the coloured eartips, as in the set-up above, please refer to Aurical Manual page 3-32 to 3.41.* You may want to continue to measure thresholds in dB HL for diagnostic purposes but note possible errors due to small ear canal volumes and transducer calibration issues- see Kevin Munros
6、 lecture on day 2 of the generic event. To use a custom earmould for audiometry you need to remove the probe tip and attach the RECD coupling to the end of the plastic tube. You can then attach the custom earmould (Figure 2). For comfort and work flow efficiency you can also replace the thicker sili
7、con tube with your usual REM thin probe tube. In doing this you have the same test set up required to measure a RECD.Figure 2. Transducer with thicker tubing and insert nipple to allow attachment of earmould.Before any measurements are obtained the silicone probe tube must be calibrated. To avoid ha
8、ving to remove the probe tube before testing it is advisable to calibrate the probe tube in the REM module first, save your calibration and exit and then calibrate the probe tube in the Audiometry module. Please follow the instructions below which assume you have already called up a patient via Audi
9、tbase.1. Open AURICAL REM module, you are going to calibrate your probe tubes. If the DSL target set-up page defaults on your screen click on CANCEL. Check to make sure you are in In-situ SPL*. Prepare to calibrate the probe tube:* If you are in Coupler Test rather than In-situ SPL click on MODE and
10、 un-tick Coupler Test. Use a new black tip probe tube, attach it to the probe mic attachment then position the end of the probe tube so that it is aligned with the reference microphone. Hold the probe tube and reference microphone facing the loudspeaker at the same distance you will be placing the i
11、ndividual (90cm as recommended by the manufacturer). Calibrate left and right ears if you are fitting bilateral hearing aids. SAVE by clicking on the GREEN save and exit TICK (top right of screen).2. Open AURICAL AUIDIOMETRY module. Click on HL/SPL tool bar and click on dB SPL. You should be in a SP
12、Logram format.3. Click on the TEST MODE tool bar and select PROBE CALIBRATION. 4. With the end of the probe tube still over the reference microphone opening hold the transducer 15cm from the loudspeaker. Calibrate both the left and right probes.5. Click on TEST MODE tool bar again and select SPL CAL
13、IBRATION. 6. You are now going to place the probe tube in the ear canal with the intention of placing the end of the tube 5-6mm from the ear drum. Make sure you use otoscopy to help guide the probe tube into the correct position. The probe tube black marker should be placed at the intra-tragal notch
14、. Use age appropriate guidelines when measuring the length of the probe tube. Check to make sure the end of the tube is approx 5mm past the end of the ear mould. Once the probe tube is in the correct position carefully place the earmould in the ear, taking care not to displace the probe tube. Use lu
15、bricant if you are working with a soft earmould or young child. Attach the RECD coupling end of the thick plastic tubing to the end of the earmould tubing (see picture). Check that Output is SOUNDFIELD INTERNAL and click on start. The software will quickly present a 70 dB signal across frequencies t
16、o use as a reference when determining actual SPL for each determined threshold. Exit when calibration is complete. You are now ready to commence standard audiometric testing, but thresholds will be recorded in dB SPL rather than dB HL.7. Once you have completed testing you may want to visualise the
17、audiogram in HL. To do this click on HL/SPL on the tool bar and click on HL. Toggle back to SPL when you are ready to exit the program. Click on the GREEN TICK to save and exit.8. Click on AURICAL REM to re-open your REM software. The probe tubes should already be calibrated so you are ready to comm
18、ence verification. If you are going to verify the hearing aid in-situ remove the RECD tubing and attach the hearing aid to the earmould. Check that you are in In-situ SPL mode. If you are going to verify in the coupler you need to measure a RECD. 9. Click on MODE , ensure COUPLER TEST is selected an
19、d then click on RECD. Make sure Do coupler step first isnt ticked and proceed with measuring Step 1 which is the real ear portion of the RECD. The earmould, probe tube and RECD transducer should already be in the correct position. Click on START. Carefully remove the transducer from the test ear and
20、 attach the end of the thick tubing to the coupler and press START (or if you have measured the coupler response at the beginning of the day click on re-use saved coupler measure. This avoids you having to remove the earmould). This is the second part of the RECD measurement (coupler test) and what
21、you will see on your screen is the resultant RECD. 10.Click on EXIT and you should see the RECD on the little gain screen on the right side of the screen and Coupler audiogram and targets on the big dB SPL screen. If you have this the other way round click on VIEW and select SPL/Gain.11.If you are h
22、appy with the RECD click on the GREEN TICK to save and exit. This is good practice as if the software crashes at least you have saved the measurements that required child co-operation. You are now ready to open up the hearing aid manufacturer software. Some manufacturer software will automatically use the measured RECD to help Auto-fit the hearing aid to prescribed targets (Phonak). Re-open the REM software and attach the hearing aid to the coupler and verify the response in the coupler. The child does not need to be present at this stage.
