Headphones
Headphones were a set of two speakers that fit over one's ears to allow one to listen closely to a transmitted message. 

In a 2374 Hirogen simulation of Nazi Germany, an SS radio operator wore headphones to listen to his two-way radio. ()

In 2399, Doctor Agnes Jurati wore headphones while she was listening to Kasseelian opera outside the Daystrom Institute in Okinawa. ()

See also
 Earmuffs
 Earphone
 Earpiece
 Headset

External link

Communications technology