The effectiveness of ten different ear-protectors (6 types of earmuffs and 4 types of earplugs) has been tested under laboratory conditions and in the real occupational environment.

Three methods were used:

(1) physical, utilizing a dummy head; (2) subjective, real-ear, executed on trained human subjects; (3) subjective, measuring TTS2 resulting from occupational, one-workday exposure.

It could be shown that the ear protection efficiency ascertained on the basis of TTS2 measurements on workers exposed to noise in their occupational environment is, in nearly all cases, smaller than the efficiency expected, taking into account the sound damping of the same protectors, tested under laboratory conditions, using the physical or real-ear method.