Some speakers talk too fast. “There are various strategies. Some interpreters think it’s best just to stop and just say the delegate is speaking too fast.” Miles herself doesn’t find that useful because people have a natural pace, and someone asked to slow down is likely to pick up speed again. The alternative is to précis. “You have to be quick on the uptake. It’s not just language skills in this job, it’s being quick-brained and learning fast.”

Challenges of this kind make simultaneous interpretation tiring, and explained why the two interpreters took it in turns to rest every half an hour. Watching by video is even worse. “We don’t like it at all,” Miles told me. Studies confirm that the process is more exhausting and stressful, probably because body language and facial expressions provide part of the message, and are harder to decipher when working remotely. “You get fewer visual clues as to what’s going on, even with a video link,” said Miles.

Then there’s the tedium. Crisis talks in New York might be gripping, but the average politician, never mind the average technical expert on marine regulations, isn’t likely to induce rapt attention for hours on end. The audience may slumber, but the interpreter must remain vigilant. As the meeting sailed on into a polyglot fog of procedural niceties and resolutions, each with sections and subsections, I realised how tiring this vigilance must be. Having nodded off in many a science conference – even once when chairing – I was in awe of the interpreters’ fortitude.

Mental networks

Moser-Mercer trained as an interpreter – she is fluent in German, English and French – before being sidetracked by neuroscience. “I got very intrigued with what was going on in my brain while I was interpreting,” she says. “I thought there has to be a way to find out.” When she arrived at the University of Geneva in 1987 there wasn’t a way – the interpretation department was concerned with training, not research. So she set out to create one by collaborating with colleagues in the brain sciences.

“Language is one of the more complex human cognitive functions,” Narly Golestani, the group leader of the university’s Brain and Language Lab, tells me during a recent visit. “There’s been a lot of work on bilingualism. Interpretation goes one step beyond that because the two languages are active simultaneously. And not just in one modality, because you have perception and production at the same time. So the brain regions involved go to an extremely high level, beyond language.”

In Geneva, as in many other neuroscience labs, the tool of choice is functional magnetic resonance imaging (fMRI). Using fMRI, researchers can watch the brain as it performs a specific task; applied to interpretation, it has already revealed the network of brain areas that make the process possible. One of these is Broca’s area, known for its role in language production and working memory, the function that allows us to maintain a grasp on what we’re thinking and doing. The area is also linked with neighbouring regions that help control language production and comprehension. “In interpretation, when a person hears something and has to translate and speak at the same time, there’s very strong functional interplay between these regions,” says Golestani.