Relay, and what it costs
When no one in the booth has both languages, the speech travels through a third — and every link in that chain carries a price.
When no interpreter has both languages, the speech goes through a third — and every relay adds delay and one more chance to lose something.
How relay works
In a meeting with many working languages, it is rarely possible to staff every booth with interpreters who can work directly from every source language. The solution is relay: one interpreter renders the original into a pivot language — English or French, most often — and the other booths listen to that rendering rather than the floor. A delegate speaking Finnish at a Brussels session may be heard in the Arabic booth only as reconstructed English. Two transformations have happened, and only one of them was heard by the room.
Under load the first things to go are numbers, names and lists, which is why they are written down rather than remembered. What the ear drops first
The mechanics are straightforward. The pivot booth feeds its output into the system on a dedicated channel; the relay booths select that channel on their consoles rather than the floor channel carrying the original speaker. From the listener's point of view nothing changes — they hear their language, delivered at normal pace. The cost is invisible in the audio and immediate in the content.
What gets lost
Relay introduces latency before the second interpreter has even opened their mouth. The pivot interpreter is already a few seconds behind the speaker; the relay interpreter is behind the pivot. In simultaneous interpreting, delay compounds. The relay interpreter is working from a text that is itself a first-pass interpretation under pressure — incomplete sentences, provisional word choices, and the occasional structural decision made in real time that the original speaker never made at all.
Numbers and proper names are the first casualties. An interpreter rendering rapidly from Hungarian may simplify a numerical comparison; the relay interpreter, hearing no floor signal to cross-check against, takes that simplification as the source. The error propagates cleanly. What the ear drops first under load — numerals, names, lists — is exactly what relay strips of its safety margin, because the margin of checking against the original is gone.
A meeting day is longer than the speaking day, and preparation is most of the work. The whole shift
Idiomatic register suffers next. The pivot interpreter may reach for a neutral English phrasing because neutral English is fast and safe; the relay interpreter then renders that neutrality into their target language, and the coloring the original speaker put on a phrase — the studied informality, the deliberate formality, the irony — has been flattened twice over. The speaker's meaning survives. The speaker's voice rarely does.
Relay can also compound structural ambiguity. A pivot interpreter who resolves an ambiguous sentence one way gives the relay interpreter no option; the ambiguity is decided before the relay stage begins. If the pivot interpreter chose wrong, the relay interpreter cannot know it.
The institutional reality
AIIC, the international professional association for conference interpreters, acknowledges relay as a practical necessity while noting that it is, by definition, at one remove from the original. In the major institutional language regimes — the European Union, the United Nations, the African Union — relay is not an emergency measure. It is a planned part of the working day, because the number of language combinations active in a single meeting exceeds what can be staffed with direct pairs. The United Nations Office at Geneva operates across six official languages; the European Parliament in principle maintains all official EU language pairs, but relay is used wherever direct coverage would require booths that do not exist.
From the listener's point of view nothing changes — they hear their language, delivered at normal pace
The discipline's answer to this is careful pivot selection — choosing pivot languages that the relay booths trust, and staffing pivot positions with interpreters whose speed and accuracy are high enough to absorb the extra pressure. The pivot interpreter, unlike the floor interpreter, knows that every booth in the room is depending on them. The failure mode of a bad pivot is not one mistranslation but many, delivered simultaneously into every language downstream.
There is no technical fix for what relay costs. Better audio, lower latency, cleaner console feeds — all of these help at the margins. The gap between one transformation and two remains.