Translating a foreign language is a mentally taxing process. It can take a good translator years to train the appropriate functions in his or her brain, to a point that it is a natural cognitive function. One of the biggest things that gets in the way of training this process is stress.
Stress is an unavoidable part of any kind of work, not least with foreign language translation. To have multiple people talking across or to you, in a foreign place, and usually in a professional setting, is no doubt a mentally challenging task.
The first thing to remember is that you cant get around the stress, you have to manage how it affects you. Stress levels are benefited if your mind is calm. If you are not well rested, your mind will be in a scattered state. Make sure that you get the right amount of sleep at the right time.