Which of the following is NOT a key element in voice signaling for cranes?

In voice signaling for cranes, a clear and effective communication method is crucial, but communication method itself is not classified as a key element in the signaling process. Rather, the key elements that facilitate successful signaling and safe crane operation include specific commands or signals like "Function Stop" and directional cues, which indicate both what action is to be taken and the direction of that action.

"Function and Direction" are important elements because they provide precise information about what needs to happen and how it should be executed. This kind of specificity is essential for preventing accidents and ensuring that everyone on the job site understands the expected actions.

On the other hand, "Distance and Speed," while relevant to the operations of crane movement, aren't typically described as fundamental elements of voice signaling itself—they relate more to the operational parameters of the crane's movements rather than the clarity of the signals used to communicate those movements. Thus, the option indicating "Communication Method" is not a specified key element among those that directly contribute to the signaling protocols employed in crane operation.