Noise Reduction of Unexploded Ordinance Detonations using Tunable Acoustic Resonators

Controlled detonation of unexploded ordinance (UXO) in preparation for offshore wind farm foundation installations can produce very high amplitude noise which may be harmful to marine life. The mitigation of this explosive noise is considered a major challenge, and one that has not yet been fully investigated. This paper discusses a tunable acoustic resonator-based underwater noise abatement system that can be applied to the reduction of UXO noise as well as other types of underwater noise. The system consists of arrays of air-filled resonators which surround the noise source and whose size and shape are tuned to optimally attenuate noise in frequency bands of interest. Laboratory testing on noise generated by combustive sound sources used to simulate UXO noise will be discussed, as will important operational and engineering considerations when working around underwater explosions. The method of deploying these resonators in large numbers in a simple deployment framework, operational advantages of this approach, and future projects using this technology will finally be shared.