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 useful 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 thresholds 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 supplied 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 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 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 silicon 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 having 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 Auditbase.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 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 individual (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 SPLogram 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 CALIBRATION. 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. 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 lubricant 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 to 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 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