Apparatus for reproduction of sound; apparatus for sound level measurement; apparatus for sound transmission; digital sound processors; ear protectors against sound; sound processors; sound receiving head sets; anti-noise apparatus for noise suppression; anti-noise filters; apparatus for measuring noise; electronic noise cancellation apparatus; noise cancelling apparatus; noise suppression apparatus; noise suppressors (electrical components); ear defenders; ear plugs; ear protecting devices; ear protectors; ear protectors against sound; earphones (other than hearing aids for the deaf); hearing aids, other than for the deaf; control centres being parts of electrical speech communications; speech communications apparatus for use in noisy environments; speech processors; speech recognisers; computer software; cards incorporating electronic chips; chips (integrated circuits); central processing unit boards; circuit boards; battery chargers; battery packs; batteries