If the noise is occurring with the top down, then: Check the "saddles" that the alignment pins at the front edge of the top set into, when in the down position. Typically, this will be more of a squeak than a rattle. The OEM felt liner on the saddles wears out and there you go. Replace with self adhesive silicone tape.
If a rattle with the top up: Check the Tulip Panel behind the seats. With the top in the up position, a bar from the top mechanism rests against the edge of the Tulip Panel. The bar is wrapped with an OEM plastic tape. The tape wears out, and then the Tulip Panel will rattle against the bar. Replace the tape with self adhesive silicone tape, problem solved. (if it has been rattling for a while, it may have chipped the edge of the tulip panel as well)