REAR Measures to Verify Directional Performance (Revit, 2000)
Reference microphone OFF.
Measuring only at 00 does not provide information on directional performance.
Need to make 2nd measure with the real-ear loudspeaker in the “null.” (e.g., Phonak AZ and Senso at 1800; Prisma and Signia @ 110 or 2500)
Hearing aids with WDRC may present a potential problem because gain increases when the signal is in the null (gain increase as input level decreases). Thus, the “back” measure may not display the ”full” potential of attenuation from the rear.