Question

why can astronauts hear each other when using radios? (we are in the wave unit so it has something to do with waves and stuff) thank you

Answer 1

It's simply because the sound waves produced within their helmet are picked up by the microphone, they are converted to radio waves which can travel through a vacuum to the other astronaut's radio receiver. The receiver then converts the radio waves back into sound waves that the other astronaut can hear.

Remember, there is air within the helmets so sound waves can travel within them.