Answer:
A modulator
Step-by-step explanation:
This device is called a modulator and it does the task of modulation. The act of modulation influences data information on the carrier, allowing signal to be sent over a bandpass frequency range.
The Modulator is what controls an input audio signal which is called a carrier. It does not make a sound. What it does instead is to change the original carrier sound wave. The work of the Modulator as evident in the question is the conversion of information signal to a signal compatible with the medium over which it is going to be transmitted.