Real ear measurement is a method used by an audiologist to make sure that hearing aids are set up the right way for an individual by measuring the sound levels in ear canals.
Most real-ear measurement systems require you to calibrate the probe tube prior to conducting real-ear measurements. Probe tube calibration accounts for the acoustic effects the probe tube introduces as sound travels through it (e.g., while placed in the ear canal) to the probe microphone during actual use conditions. In effect, calibration removes the acoustic effects the probe tube and microphone introduce during real-ear measurement, thereby making the probe tube and the microphone ‘acoustically invisible.’As the probe tube calibration values will be applied to all probe microphone readings via a mathematical correction, careful and accurate probe tube calibration is particularly important. Audiologists should refer to the specific manufacturer’s supporting documentation for instructions on how to calibrate their system and what to expect in terms of the probe tube calibration curve for their equipment.
Prior to conducting any real-ear measurement, it is important to perform an otoscopic examination. This serves to provide information about a number of factors that could impact your results, including the presence of cerumen or other debris which may interfere with placement of the probe tube and/or block the probe tube. If the ear canal appears occluded or if cerumen is located where it may affect probe tube placement, the cerumen should be removed prior to conducting real-ear measurements (Tecca, 1994). Otoscopic examination also provides details regarding the specific anatomy of the ear canal, which is useful when placing the probe tube.