Comments on combinations of hearing protection equipment

If ear plugs and ear muffs are worn simultaneously, the sound attenuation of the combination may be reduced, owing to leakage caused by contact between the ear plugs and the ear muffs (DGUV Regel 112-194 (to date: BGR/GUV-R 194) governing the use of hearing protection, January 2015, Section 3.2.1.1.8 at www.dguv.de/fb-psa, in German).