With the high levels of noise inside a Panzer communication was very difficult. To communicate with other vehicles, other than by radio, was almost impossible.
The German engineers solved the problem of internal communications by an internal intercom which linked the crew and allowed them to communicate via headphones and microphones. The German practice at the time was to use a throat microphone which had two small microphones against the side of the throat; these would be pressed to speak to the rest of the crew. The radio set over that also allowed for broadcasts to the rest of the unit. The headset had a pair of headphones to muffle the sound of the engine but it generally was a very loud engine anyway. For communications between the tanks themselves, all German machines were equipped with radios. In the early war years, there were no such refinements on the Russian side.
In the famous T-34 for example, as good as the tank was, the communication was very poor. Early models had no radio at all so the commander had to get out of his turret and wave two flags about, one red and one green, and give signals like a ship on the high seas. This primitive system had initially been used by the Panzerwaffe, who of course discovered that it did not work very well. It was only much later that the T-34/85 had a proper radio for contact with each crew member and of course to Headquarters.
A hurried field conference, as the men of the leading tanks in a German formation threatening Dubno are briefed on their next mission.