| 摘要 |
PURPOSE:To enable measurement of a minute change in a surface wave sound velocity by determining the incident angle theta of an ultrasonic wave giving a minute sound pressure reflectiv ity with the occurrence of a surface wave and by determining the surface wave sound velocity CRS = C/sin theta from the incident angle theta and a sound velocity C in a known shoe. CONSTITUTION:In a state wherein the contact surface 14 with a specimen 1 to be inspected of a shoe 17 of each of probes 20 of which incident angles theta are changed variously is not brought into contact with the specimen 1, and ultrasonic wave is transmitted from a vibrator 18, reflected at a point (e) of intersection and received by a vibrator 19, and thereby a reflected sound pressure E0 serving as a reference is measured beforehand for each of the probes 20. Next, in a state wherein the contact surface 14 of the shoe 17 is brought into contact with the same place of the specimen 1 sequentially, the ultrasonic wave is transmitted from the vibrator 18, reflected at the point (e) of intersection and received by the vibrator 19, a reflected sound pressure E1 on a different-material interface is measured for each of the probes 20, and a sound pressure reflectivity E1/E0 is determined. Subsequently, reflectivities E1/E0 are compared with one another and the incident angle theta of the ultrasonic wave giving the minimum of the reflectivities E1/E0 accompanying occurrence of a surface wave is deter mined. Then a surface wave sound velocity CRS of the specimen 1 to be inspected can be determined by CRS = C/sin theta. |
