why must astronauts use microphones and headphones in outer space

Sound is made up of waves traveling through a medium like air or water.Space is a vacuum, and this lack of a medium means sound does not carry in space.  There is no atmosphere to carry the sound waves. Astronauts therefore have to use headphones and microphones to hear each other in the vacuum of space.

because in space there's no oxygen and you need oxygen to talk and you would have oxygen in your tank but no one could hear you with a helmet on so that's y u need a mic in space. yw