Abstract: A respirator system includes a facepiece, a communication system and a control system in operative connection with the communication system. The control system is adapted to control voice transmittal via the communication system based at least in part upon measurement of a variable other than sound. The variable is related to speech of a user of the facepiece. The variable may, for example, be related to respiration of the user.

Abstract: A user navigation guidance system, including: at least one personal inertial navigation module associated with at least one user and configured to generate navigation data; at least one central controller configured to: directly or indirectly receive at least a portion of the navigation data; and generate global scene data in a global reference frame for locating users, features, and/or positions; at least one navigation guidance unit configured to: directly or indirectly receive at least a portion of the global scene data from the at least one central controller; and generate guidance data; and at least one display device configured to generate and provide visual information to the at least one user. A user navigation network system is also disclosed.