Abstract: An earpiece has a structural configuration effective to removably interlock its outer surface contiguously to the outer ear auricle of the earpiece wearer. A microphone substantially exclusively receives, from the air of the external auditory canal, outbound voice sounds caused by the reverse modulation of the tympanic membrane when the earpiece wearer speaks. An outbound audio circuit is electrically connected to the microphone which converts the outbound voice sounds to electrical voice signals. The outbound audio circuit amplifies the outbound electrical voice signals to a preselected fixed level output gain and removes noise from the voice signals.

Abstract: An earpiece has a structural configuration effective to removably interlock its outer surface contiguously to the outer ear auricle of the earpiece wearer. A microphone substantially exclusively receives, from the air of the external auditory canal, outbound voice sounds caused by the reverse modulation of the tympanic membrane when the earpiece wearer speaks. An outbound audio circuit is electrically connected to the microphone which converts the outbound voice sounds to electrical voice signals. The outbound audio circuit amplifies the outbound electrical voice signals to a preselected fixed level output gain and removes noise from the voice signals.

Abstract: A telecommunications system including a mobile unit is protected from operator-induced disruption by disabling the operator-adjustable controls of the mobile unit and fixing the operating parameters of the mobile unit. A supervisory apparatus incorporating supervisory circuit elements replacing the adjustable circuit elements associated with the operator-adjustable controls may be plug-connected between the main chassis and the control head of the mobile unit.