Apparatus for measuring impact sound insulation provided by a shared dividing structure comprising a floor of a first room of a building and a ceiling of a second room of the building, which apparatus comprises: (i) a tapping machine for generating a tapping sound on the floor of the first room of the building; (ii) sound measuring means which is separate from the tapping machine and which is for measuring the level of the sound in the second room in the building, with the second room being underneath the first room and such that the first and second rooms (8, 12) form a room pair with the shared dividing structure comprising the floor of the first room and the ceiling of the second room; and (iii) mounting means for mounting the tapping machine on the floor of the first room, (iv) the apparatus includes mover means by which the tapping machine is movable over the floor of the first room; (v) the apparatus includes remote control means for remotely controlling operation of the mover means over the floor of the first room; and (vi) the apparatus is such that in use the tapping machine, the mounting means and the mover means are in the first room, the second measuring means is in the second room, and a person who is in the second room is able to control movement of the tapping machine over the floor of the first room; the apparatus characterised in that it further includes lowering and raising means for causing the mounting means to be lowered to a first position in which the mounting means contacts the floor of the first room when measurement of the level of the sound in the second room is to take place, and to be raised to a second position in which the mounting means does not contact the floor of the first room when movement of the tapping machine over the floor of the first room is to take place. (i) a tapping machine for generating a tapping sound on the floor of the first room of the building; (ii) sound measuring means which is separate from the tapping machine and which is for measuring the level of the sound in the second room in the building, with the second room being underneath the first room and such that the first and second rooms (8, 12) form a room pair with the shared dividing structure comprising the floor of the first room and the ceiling of the second room; and (iii) mounting means for mounting the tapping machine on the floor of the first room, (iv) the apparatus includes mover means by which the tapping machine is movable over the floor of the first room; (v) the apparatus includes remote control means for remotely controlling operation of the mover means over the floor of the first room; and (vi) the apparatus is such that in use the tapping machine, the mounting means and the mover means are in the first room, the second measuring means is in the second room, and a person who is in the second room is able to control movement of the tapping machine over the floor of the first room; the apparatus characterised in that it further includes lowering and raising means for causing the mounting means to be lowered to a first position in which the mounting means contacts the floor of the first room when measurement of the level of the sound in the second room is to take place, and to be raised to a second position in which the mounting means does not contact the floor of the first room when movement of the tapping machine over the floor of the first room is to take place.