Author
EDOUARD G. NESVIJSKI and ODILON P. CAVALHEIRO Federal University of Santa Maria, Brazil

Abstract
The present paper is devoted to analysis of problems and possibilities of application of some acoustic (sonic and ultrasonic) methods for nondestructive testing of specimens in the laboratory and of real structures in the field. The following objectives are addressed: choice of integral or differential approaches to testing; analysis of existing ultrasonic methods (mechanical pulse velocity and impact-echo techniques); classification of problems that could be solved with the kelp of ultrasonic methods. Papers devoted to NDT of masonry are analysed. Some experimental results showing advantages of differential approach to ultrasonic testing are presented. A new measuring technique (ultrasonic surface wave technique) using dry point contact transducers is demonstrated.