Small foldback speakers mounted discreetly behind the front pair of sound
reinforcement speakers relay audience questions from hand held radio mics to
the presenters on the stage.
This solves the problem of the presenters being 'behind' the usual speakers
so not being able to hear audience questions.
There are other styles of speakers available. Small speakers can be mounted
in the lectern or on the trib desk. Other units can be placed at the front
of the stage.