Headsets, headphones, earphones and earbuds; hands-free communication apparatus and equipment for mobile telephones; microphones; telephones; telephone adaptors; telephone cables; battery chargers; hands-free communication apparatus and equipment for use in offices and with personal computers; wire and wireless communication apparatus; communication software and communication interface units; busy light indicators for use with wire and wireless communication apparatus; software; noise measurement apparatus; noise level indicators; apparatus for recording, transmission and reproduction of sound