Home NR614 Underwater Radiated Noise (URN) This Rule Note provides requirements on measurement of underwater radiated noise emitted by any self-propelled ships. It aims at managing and mitigating acoustical impact on marine fauna on both shallow and deep waters. Reference Title Edition NR614 R02 Underwater radiated noise (URN) Jul 2018 check related documents: NR467 Rules for the classification of steel ships Check other Bureau Veritas rules and guidelines.