Talkback (noun)

1. A facility in a broadcasting studio allowing listeners to call in and participate in a live program.
2. A system or device allowing a performer on a stage or in a studio to hear the performance or a recording of it while still performing.

Origin:

Mid 20th century: from the verb talk back.

Examples:

1. The talkback system allowed the singer to hear the orchestra while she performed.
2. The talkback facility allowed the listeners to call in and ask the host questions.
3. The talkback feature allowed the performers to hear the live recording and make changes accordingly.
4. The talkback system allowed the director to communicate with the actors during the performance.
5. The talkback enabled the live audience to participate in the radio program.