# Underwater Radiated Noise Prediction Method of Cabin Structures under Hybrid Excitation
## 5 Conclusions  
Aiming at the engineering limitations of traditional ship vibration online monitoring and noise prediction methods, we first studied the vibration and sound characteristics of the cabin structure under the hybrid excitation of force and sound and the coupling  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Frequency** **(Hz)**} & \multicolumn{4}{c}{**Investigation Point 1**} & \multicolumn{2}{c}{**Investigation Point 2**} & \multicolumn{2}{c}{**Investigation Point 3**} & \multicolumn{2}{c}{**Investigation Point 4**} \\ \cline{2-9}  & **Vibration** & **Synchronous** & **Vibration** & **Synchronous** & **Vibration** & **Synchronous** & **Vibration** & **Synchronous** \\  & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** & **Monitoring** \\ \hline
100 & 8.54 & 4.87 & 6.28 & 3.43 & 7.24 & 3.74 & 8.59 & 3.5 \\
125 & 6.49 & 3.49 & 7.92 & 2.68 & 4.65 & 4.87 & 5.06 & 3.66 \\
160 & 4.67 & 0.57 & 9.46 & 2.97 & 4.1 & 4.29 & 4.1 & 0.04 \\
200 & 3.19 & 0.52 & 5.86 & 2.76 & 3.53 & 4.11 & 0.85 & 0.52 \\
250 & 3.42 & 2.53 & 6.38 & 3.01 & 3.2 & 0.44 & 7.38 & 1.76 \\
315 & 3.98 & 1.91 & 5.3 & 2.26 & 6.18 & 0.44 & 7.28 & 0.08 \\
400 & 3.06 & 2.44 & 8.13 & 4.99 & 7.14 & 0.33 & 3.34 & 2.68 \\
500 & 2.19 & 1.88 & 3.14 & 0.46 & 4 & 2.01 & 5.57 & 2.54 \\
630 & 4.99 & 1.88 & 2.6 & 1.18 & 5.43 & 1.76 & 2.95 & 0.28 \\
800 & 5.66 & 2.33 & 6.26 & 2.78 & 2.04 & 0.73 & 3.73 & 3.1 \\
1000 & 3.75 & 1.76 & 5.23 & 2.81 & 3.42 & 3.62 & 4.37 & 1.16 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Radiation noise prediction error.  
Figure 17: Far-field radiation noise prediction results: (**a**) Investigation point 1. (**b**) Investigation point 2. (**c**) Investigation point 3. (**d**) Investigation point 4.  
characteristics of vibration and acoustic monitoring information theoretically. On this basis, we propose a method of underwater radiation noise prediction for cabin structures based on synchronous vibration and acoustic monitoring combined with OTPA and the wave superposition method. This method solves the problem of missing radiation noise caused by sound excitation in traditional vibration monitoring by adding acoustic monitoring points inside the cabin. Compared with the prediction results of the traditional vibration monitoring method, it was found that the proposed method can effectively improve the prediction accuracy of the underwater radiation noise of the cabin structure, and the prediction accuracy is more obvious in the middle- and low-frequency bands. The forecast error of radiation noise increases with the increase of frequency, but the average forecast error of the one third octave band below 1 kHz is less than 4 dB. In addition, the proposed method can predict the radiation noise at any position in the far field of the ship cabin structure, which makes up for the limitations of the traditional OTPA method. The effectiveness of the proposed method was further verified by the model test of the tank section. In addition, practical problems such as the noise prediction of multi-cabin structures and the optimal arrangement of monitoring points need to be further studied in subsequent work.  
Conceptualization, S.S. and Q.G.; methodology, S.S. and Q.G.; validation, Q.G.; formal analysis, S.S. and Q.G.; investigation, Q.G.; resources, S.S.; data curation, Q.G. and B.Y.; writing--original draft preparation, Q.G.; writing--review and editing, S.S. and H.Z.; supervision, S.S. All authors have read and agreed to the published version of the manuscript. This research received no external funding.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflict of interest.