While treadmills are designed to be as quiet as possible, if you live in an apartment or a shared building it is possible that the sound can carry.
To minimise noise, we recommend placing a rubber treadmill mat beneath your treadmill to help insulate it against the ground. You could also use a section of rubber commercial gym flooring if needed. These solutions are both ideal for minimising noise and also protecting your floor, as commercial treadmills are heavier than domestic units.