Every conversation involves interpretations. They serve as a working hypothesis allowing to perform the task at hand.
In the case of simultaneous interpretation, they are based on the interpreter’s experience in translating the given subject and her ability to convey the message in an as complete manner as possible. The people benefiting from the interpreter’s translation need to trust her competence in understanding the original message and conveying it in another language. The interpreter has to use all her senses to be able to do the translation on the fly. Her challenge being, that she cannot interrupt the flow of the conversation to verify if her understanding is correct.
For almost everyone else, there is the possibility to verify. When doing so, the working hypothesis is a means to adjust understanding to reach a common ground.
That such verification often doesn’t happen can have multiple reasons. The most common, however, is that people don’t realize that it would ease the flow of the conversation to ask.
They may even assume that they are obliged to understand, making it a question of status. However, it doesn’t free them from the need to understand the missing information. In their need to solve their confusion, they expand on their own interpretations with beliefs and mind-reading.
It transformed the interpretation from a working hypothesis into an assumption.
As the conversation continues, it now depends on luck to notice that the conversation is based on two different assumptions.