As you may be knowing, sound always needs a 'medium material' to travel from one thing or place to another. At our Earth, we can hear sound because the Earth has a sound medium which we call as 'air'. So it can be heard from one point to another. Where as, at the Moon there is not a single bit of atmosphere(as far as I know). So, as the moon has no sound medium. It can't be heard from one point to another.To conclude sound doesn't travel at all in the moon which means its slower than the Earth.
Hope it helps. Please vote it the brainiest answer.