An electromagnetic acoustic transducer for exciting ultrasound in a ferromagnetic material under test (2), comprises magnetic means (6) arranged to be moved relative to the material under test (2) to magnetise a surface layer of the material, and an electrical winding (8) supplied by an alternating current source, the magnetic means (6) and the electric winding (8), in use, being applied in sequence to the material under test (2) whereby the electrical winding (8) is positioned adjacent the material subsequent to magnetisation thereof by the magnetic means (8), the alternating magnetic flux created by the winding (8) interacting with the remanent magnetisation of the material to create ultrasonic vibration of the material.