I'm a novice. I'm trying to communicate wirelessly between an electret microphone and a speaker using HC-12 modules. What I have set up in the picture below works in the sense that a signal is sent to the speaker when I blow hard enough on the electret microphone, seemingly indicating that everything may in fact be wired correctly. However, the speaker just makes a deep buzzing noise that doesn't at all resemble the sounds that go into the microphone.
You can see in the picture that I'm using two amplifier modules - one for the transmitter and one for the receiver. I'm powering the transmitter with a rechargeable 9V battery and the receiver with 3 rechargeable AA batteries (~3.8 V).
I've verified that the HC-12 modules being used work independently. I've also verified that the microphone, amplifiers, and speaker work (when connected via wires, audio signal is transmitted just fine from the microphone to the amplifier to the speaker).
Can someone help me to identify what I'm missing?