9 Headphones; earphones; earplugs for sound-deadening; audiometers; amplifiers, filters, digital and analog signal processors, special purpose electronic circuits and chips for signal processing, speech enhancement processors, voice controlled electronic circuitry, digital active noise reduction circuitry, and audio interfaces for communications systems, all for use in and/or together with earphones, headsets and audio systems; sound amplification, silencer and noise elimination circuitry for use in and/or together with earphones, headsets and audio systems for the filtering, reduction or elimination of extraneous noise or sound, and related electronic circuitry and devices used outside of the auditory canal in conjunction therewith; earplugs for divers; two- or multi-directional communication systems, radio systems and intercom systems comprising microphones, earphones, headsets and/or communications transducers and associated electronics communications transmitters and receivers with amplification, filtering, noise reduction, noise elimination and/or voice-activated control circuitry; communications, radio and intercom systems comprised of transmitters, receivers, microphones, earphones and electronic noise filters, all with integrated sound - and noise eliminator functions or with noise eliminators for the filtering, reduction or elimination of extraneous noise or sound; microphones, earphones, headsets, loudspeakers and sound transducers; microphones, earphones, headsets and sound transducers with integrated sound - and noise eliminator functions or noise eliminators for the filtering, reduction or elimination of extraneous noise or sound; electronic circuitry; computers, computer peripherals, integrated circuit computer chips and electronic computer circuitry; software for use in digital signal processing and enhancement, noise filtering, and in the filtering, reduction or elimination of extraneous noise and sound, and for two-way radio communication in highly stressful, noisy and difficult environments; electronic testing equipment and electronic sound and wave analysis apparatus for testing, tuning and evaluating sound amplification, transmission and filtering in highly stressful, noisy and difficult environments