Use The In-Situ Option

by Larry Revit, hearing scientist

 

To Save Dispensing Time and Improve Initial Customer Satisfaction

The In-Situ Option lets the dispenser set the controls on a hearing aid to match a custom target insertion gain curve, before the client arrives! You create a target curve in Quik-Probe, and then use In-Situ with Multi-curve to set up the hearing aid to match. It's easy! Here's how you do it:

  1. In Quik-Probe, enter the client's audiogram and select the appropriate target conversion. While still in Quik-Probe, use Multi-Curve to copy the target curve (CURVE 4) to REFERENCE 1.
  2. Press [RESET] to go to the COMPOSITE WEIGHTED GAIN test-chamber mode.
  3. Set the volume control on the instrument to a "use-gain" position. That would be about 10 to 15 dB below full-on gain. Occlude any vent and attach the instrument to the appropriate MZ coupler (preferably the MZ-1, using the client's custom earmold or shell).
  4. Press [MENU] and then [INSITU] to call the In-Situ Menu. Select "ITE", "ITC", or "BTE" for SOURCE CORRECTION, and select "OES AND INSERTION GAIN" for OUTPUT CORRECTION. Press [START] to run the In-Situ Option. What you see is the estimated insertion-gain response of the instrument.
  5. Set the source amplitude as will be used for verifying the insertion gain, once the client arrives. That would usually be about 65 dB SPL, the averaging long-term level of speech.
  6. Now go to Multi-Curve and select DUAL SCALING. Choose CURVE 1 (the ongoing real-time chamber curve) to get the left scale and REFERENCE 1 (the target insertion gain curve) to get the right scale.
  7. Now you're ready to adjust the hearing aid controls to match the target, while viewing the real-time esitmated insertion-gain curve.

     

      HINTS:
    • Adjust the overall (or mid-band) gain trimmer so the mid frequencies (1 to 2 KHz) match the target.
    • Adjust the low and high tone (or band) trimmers so the low- and high-frequency slopes match the target.
    • Adjust the resonant peak trimmer so the region between 2 and 4 KHz matches the target.
    • Vary the source amplitude of the speech-weighted signal to see that any signal processing is responding properly.

 

URGENT: The important final step will be to verify the fit using Quik-Probe. Although the In-Situ Option can estimate the insertion-gain response for the average ear, for many ears you may find significant differences in the real-ear insertion response. Areas to watch out for are: Increased roll-off at low frequencies, because of venting and leakage; Sharpening of peaks near receiver resonances, also because of venting and leakage; A shifted or inverted resonant peak, because of differences in the unaided earcanal resonance; Overall gain shift, because of middle-ear impedance differences or post-operative conditions.

In most cases, however, a pre-fitting setup of the hearing aid using the In-Situ Option should do a much better job than the traditional 2cc-coupler tests, for getting as close as possible to the prescribed fit before the client arrives. That should save the dispenser valuable time with the client, and the dispenser will look better by not having to fiddle with the controls too much. In many cases, where the client's ear is close to average, the fit will be perfect the first time the instrument is placed in the ear!

Encourage your 6500 users to take full advantage of the valuable In-Situ Option.

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