What is required when normal voice communication cannot be used?

When normal voice communication cannot be used, two-way communication devices are essential for maintaining effective communication. These devices, such as radios, intercoms, or other electronic communication tools, enable parties to transmit and receive information despite the challenges posed by distance, noise, or other environmental factors. They facilitate clear and direct conversations, allowing users to convey messages promptly and accurately, which is vital in situations where voice communication is hindered.

Other methods like hand signals, visual aids, and written instructions can supplement communication but may not provide the immediacy or interactivity required in dynamic situations. Two-way communication devices are designed specifically to overcome barriers that prevent normal voice exchanges, making them the preferred choice in such circumstances.