Answer: preradio

AnswerCrossword Clue
PRERADIOLike the 1880's, e.g.
PRERADIOLike the era of highest sheet music sales
PRERADIOLike telegraphy's heyday
preradioway of transmitting sound by electromagnetic waves, without wires
preradioapparatus for sending or receiving such waves
preradiobefore the invention of radio