Abstract: As the low-frequency development of underwater acoustic detection technology, an urgent need to improve the low-frequency sound absorption performance of underwater sound-absorbing wedge (USAW) has been proposed. From modeling analysis method, low-frequency and broadband sound absorption characteristics and backing effects, the low-frequency and broadband sound absorption characteristics of the USAW are re-examined. Based on a layered-then-equivalent, transfer matrix method, the analytical relationship between the backing input impedance and the total input impedance of the USAW is firstly established, the inevitability of the backing effect on the sound absorption performance of the USAW is pointed out. A calculation error analysis shows that ignoring the shear effect of the matrix material has very little influence on the sound absorption performance of the USAW, while ignoring the water area between the arrangement gap will overestimate its low-frequency sound absorption performance. Then, by systematically comparing the difference of the sound absorption characteristics of the USAW and the sound-absorbing plate, it is found that if only focusing on the low frequency sound absorption performance, the USAW is not better than the sound-absorbing plate of the same thickness, the advantage of the USAW is mainly reflected in the balance design of low-frequency and broadband sound absorption curve. Finally, a thorough comparison of the sound absorption characteristics of the USAW under several typical backings shows that different boundary conditions have a significant impact on the low-frequency sound absorption performance of the sound absorption wedge, then the relevant mechanism is further explained.

Key words: underwater sound-absorbing wedge, low frequency, input impedance, boundary effect