noun
a system in theatres, etc., which helps people who cannot hear well. A ring of wire around the room produces a signal that can be received directly by hearing aids .
noun
a system in theatres, etc., which helps people who cannot hear well. A ring of wire around the room produces a signal that can be received directly by hearing aids .
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005