National Sun Yat-sen University /  Prof. (Distinguished) Linus Y.S Chiu

 Pain Points Solved 

Traditional ship radiated noise measurement, whether conducted in shipyard docks or open marine environments, is constrained by several long-standing technical bottlenecks. In enclosed dock environments, severe multipath interference caused by repeated reflections from surrounding structures obscures the true noise sources, significantly degrading measurement reliability. In dynamic marine environments, background noise, time-varying transmission conditions, and uncertainties in the relative position between the ship and sensors further distort the acquired data, making it difficult to accurately characterize the ship’s true acoustic source properties under different operating and sailing conditions. These limitations not only compromise the evaluation of ship silence performance but also restrict subsequent design optimization, tactical planning, and performance verification of acoustic monitoring systems.
 

To address these challenges, this technology proposes a systematic solution built upon an integrated static–dynamic underwater radiated noise measurement technology chain. For static measurements, the combination of multipath propagation effect analysis and dock-induced reflection mitigation enables dockside measurements—traditionally dominated by reflection artifacts—to reconstruct underwater radiated noise spectra that closely approximate real operating conditions. When further integrated with inboard vibration and airborne noise measurements, the full noise transmission path—from onboard mechanical sources to underwater acoustic radiation—can be quantitatively linked, supporting the establishment of a traceable and continuously improvable ship silence performance database.
 

For dynamic measurements, the integration of acoustic source localization, transmission loss estimation, and ship radiated noise source spectrum estimation enables the reconstruction of true radiated noise characteristics under different sailing states, even in complex and time-varying marine environments. This integrated approach significantly enhances the accuracy, robustness, and practical usability of radiated noise spectrum reconstruction.
 

In summary, the core value of this technology lies in overcoming key limitations of traditional methods, including insufficient measurement accuracy, inability to localize noise sources, and difficulty in separating environmental interference from source characteristics. It provides a comprehensive underwater radiated noise measurement and analysis solution applicable to both dockside and marine environments. Beyond improving the efficiency and credibility of ship silence design optimization, this technology supports ship verification, quality control, tactical noise management, and the establishment of acoustic signature databases, offering substantial practical value for ship R&D entities as well as operation and maintenance organizations.

 Technology Introduction 

1. Ship Radiated Noise Static Measurement Technology: A comprehensive technology specifically for static measurement of ship radiated noise in shipyard docks or enclosed environments, containing 6 technologies:

• Static Underwater Radiated Noise Measurement: Measures underwater ship radiated noise signals in dock or enclosed environments, capturing acoustic signals radiated underwater from the operation of main and auxiliary machinery in the entire space.
• Multipath Propagation Effect Analysis: Analyzes acoustic signal multi-path effects caused by multiple interfaces within the dock or enclosed environment.
• Multipath Propagation Effect Mitigation: Eliminates multi-path effect interference from measured underwater ship radiated noise signals to obtain noise spectrum data of the underwater ship radiated noise source.
• Inboard Vibration and Noise Measurement and Analysis: Performs multi-channel synchronous measurement and analysis of main and auxiliary machinery operation vibration and airborne noise inside the ship, measuring vibration conditions and generated airborne noise under different operating conditions, and analyzing vibration and noise spectra.
• In Situ Underwater Noise Analysis: Analyzes background noise intensity and noise spectra in dock or enclosed environments.
• Integrated Static Underwater Radiated Noise Analysis Software: Integrates underwater acoustic measurement data and inboard vibration noise measurement data to perform the analytical tasks of the above technologies.

2.  Ship Radiated Noise Dynamic Measurement Technology: A comprehensive technology for dynamic measurement of ship radiated noise in marine environments, containing 5 technologies:

• Dynamic Underwater Radiated Noise Measurement: Measures underwater ship radiated noise signals in marine environments, capturing the overall radiated noise acoustic signals of the tested ship under different sailing states.
• Dynamic Underwater Radiated Noise Data Analysis: Analyzes the overall radiated noise acoustic signals of the tested ship under different sailing states in marine environments to obtain the received signal spectrum of ship radiated noise.
• Acoustic Source Localization: Uses active and passive acoustic signals for 3D positioning of the tested ship during dynamic underwater acoustic measurement.
• Transmission Loss Estimation: Estimates the transmission loss of each frequency for the radiated noise signal from the tested target propagating to the receiving system.
• Ship Radiated Noise Source Spectrum Estimation: Combines the received signal spectrum of ship radiated noise with transmission loss at each frequency to calculate the radiated noise source spectrum of the tested ship under different sailing states.

Figure1. This diagram illustrates the complete system architecture of the ship radiated noise measurement technology, including two major modules: "Static Measurement System" and "Dynamic Measurement System." Static measurement integrates underwater noise measurement, multi-path effect analysis and elimination, inboard vibration noise measurement, and background noise analysis to reconstruct true radiated noise characteristics in docks or enclosed environments. Dynamic measurement combines signal analysis, target localization, transmission loss estimation, and source spectrum reconstruction to obtain radiated noise information of ships under different sailing states in marine environments. The integration of both provides a complete technology chain for ship silence performance assessment and acoustic signature analysis. 

 Application Examples 

This technology has been successfully applied to establish the Integrated Dynamic Underwater Radiated Noise Analysis Software. The software fully integrates both static and dynamic ship radiated noise measurement technologies and modularizes key functions according to practical measurement and analysis workflows. Core functional modules include multipath propagation effect processing, transmission loss estimation, inboard vibration and airborne noise analysis, and ship radiated noise source spectrum reconstruction. By integrating measurement data, acoustic numerical models, and marine environmental information, the system supports the entire workflow—from data preprocessing and analytical computation to comparative assessment and result visualization—within a single unified platform.
The software has been practically deployed in multiple ship noise assessment applications, including dockside static radiated noise testing, sea trial noise measurement verification, source level comparison, and noise transmission path analysis. With the support of this integrated platform, users can efficiently characterize ship radiated noise under varying environments and operating conditions, significantly reducing analysis time while improving interpretability and accuracy. The software therefore provides a robust technical foundation for shipbuilding entities, R&D organizations, and verification authorities to conduct silence design optimization, performance inspection, and long-term acoustic signature archiving.

 Related Links 

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 Patent Name and Number 

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 Industry-Academia / Tech Transfer Partner 

Tech Transfer Partner: CSBC CORPORATION, TAIWAN

 Honors and Awards  

None

 Technical Contact  

Industrial Liaison Office

National Sun Yat-sen University
Tel: +886 7-5250165
Email: gloria@mail.nsysu.edu.tw