Abstract:

Taking the precise measurement data by Hamilton’s parallel differential distance attenuation measurement method (PDDAMM) as the standard, the authors compare the Qian’s vertical coaxial attenuation measurement method (VCAMM) and Liu’s vertical differential distance attenuation measurement method (VDDAMM) with their coaxial differential distance attenuation measurement method (CDDAMM). By comparing the data from these three experiments with those by Hamilton’s method, the authors further analyze the connection of attenuation with sample length and measurement frequency as well as the benefits and drawbacks of these three experiments. Compared with VCAMM, CDDAMM is much more advisable in respect of reducing perturbations, which result from measuring instrument and the coupling between sample and transducer, and of sample length. Compared with VDDAMM, CDDAMM ensures in theory the coaxiality and directivity of compression wave in spreading process, and its data are much more precise than those by VDDAMM when using the same laboratory instrument.

Key words: seafloor sediments, acoustic attenuation, laboratory measurement