Different earhooks determine the optimum frequency response.
 
Zubehoer

The optimum frequency response can be optained with different earhooks. Three versions are available designed for specific corrections:

P (=Power), D (=damping of resonances) and E (=etymotic, i.e. the non-linear main resonances 1, 3, 5 etc. are attenuated).

Characteristic of earhook P / D / E
on the 2 ccm coupler
Earhook P: --------------
Earhook D: - - - - - - - -
Earhook E: .................
Input 90/60 dB SPL
Max. gain / Tone HN/LN