In an arrangement for transmitting power or data through a solid rigid substrate without penetrating the substrate, acoustic transducer components are mounted on the substrate by means of strain isolator elements which are welded or otherwise bonded to the substrate and providing an attachment surface to which the attachment interface of the acoustic transducer may be attached. The strain isolator element is of the same or similar acoustic impedance as the rigid substrate and may indeed be formed of the same material. Various geometries of strain isolator are disclosed, including one comprising a stalk attached to the solid rigid substrate and topped by a disc in a ‘mushroom’ configuration.