Amateur Operators Use It to Receive Sound Signals

This page is the CodyCross answer for the clue below from Prehistory, Group 1241, Puzzle 5 (Geographic Survey).

Question is: Amateur Operators Use It to Receive Sound Signals

and the answer is: HAMRADIO

Word Meaning:

HAM RADIO — (colloquial) The hobby of amateur radio communication.

Definitions from Wiktionary.