Impulsverfahren zur Messung der Reflexion von Wasserschallabsorbern in Rohren

The development of absorbers for water-borne sound covering the frequency range around 15 kc/s required special measuring methods. The technique using the sound propagation in tubes proved to be appropriate for this purpose.

A pulse method is described in this paper, which permitted the determination of the amounts and the phase angles of the reflection factors of absorber samples, having the shape of circular discs, in a tube. This method was in the first instance applied to the case of resonant absorbers. The influence of the narrow annular slot between the sample and the wall of the tub e is especially treated, furthermore the necessary elimination of the systematic error which is caused by the slot.