HP RM500SL manual Real-Ear Measurement Setup, FastFacts 10.2 REM calibration facts

10Real-Ear Measurement Setup

10.1Section overview

For safe and effective operation, the Real-Ear Measurement (REM) system must be properly set up and calibrated, the client must be properly positioned and the probe tube must be properly positioned in the ear canal. Note that the REM speaker is in the lid of the test chamber which must be open to a near-vertical position for all real-ear measurements.

Real-Ear Unaided Response (REUR): SPL, or band SPL, in the open (unaided) ear canal for a given stimulus.

Real-Ear Unaided Gain (REUG): Difference, in dB, between the REUR and the stimulus SPL, or stimulus band SPL.

Real-Ear Aided Response (REAR): SPL, or band SPL, in the ear canal for a given stimulus, with a working hearing aid in place.

Real-Ear Aided Gain (REAG): Difference, in dB, between the REAR and the stimulus SPL, or stimulus band SPL.

Real-Ear Saturation Response (RESR): The REAR obtained using a narrow-band signal at a level high enough to saturate the hearing aid (usually 85 - 90 dB SPL).

Real-Ear-to-Coupler Difference (RECD): Difference, in dB, between the real-ear SPL and the 2cc coupler SPL produced by the same transducer driven by the same signal.

This section covers the following topics:
10.2: REM calibration facts	10.6: ABR nHL to eHL setup
10.3: Calibration of REM probe microphone	10.7: Positioning the client
10.4: Calibration check for probe module	10.8: Positioning the probe tube
10.5: Max TM SPL setup

FastFacts 10.1: Real-ear measurement setup

10.2 REM calibration facts

The probe microphone and its associated tubing does not have a flat frequency response. The REM calibration process compares this response with the flat, factory-calibrated response of the REM reference microphone and compensates all subsequent probe-tube measurements for this difference. It may be performed as often as desired but will be invalidated at 1 am the following day or at 1 am the following Monday, depending on the choice of Daily or Weekly calibration interval. After the calibration has expired, you will be prompted to calibrate whenever you attempt a test that uses the REM microphones.

It is suggested that a copy of the calibration curves for the probe modules when new be posted near the RM500SL for comparison with daily or weekly curves. If there is a drift in calibration with time, the module may need replacement. See 10.4: Calibration check for probe module.

Calibration should be repeated if probe modules are switched or if a probe-tube with different dimensions is installed.

FastFacts 10.2: REM calibration facts

0611 RM500SL User’s Guide Version 2.8 Page 50