Field Report from OCEANOISE 2026 – Day 4

Global communications fiber could be used in “Digital Acoustical Sensing

Day 4 of the OCEANOISE conference focused on the themes of “Soundscapes,” “Explosives,” and “Sonar.” Much of the day spend on Soundscapes, with the first Session, and all of the “5-minute talks” and poster sessions on Soundscapes. But before I dive into Soundscapes, the other two sessions warrant some comments.

Most folks in the US are unaware of the “Unexploded Ordnance” (UXO) problem found off the coasts of Western Europe.  There are thousands of bombs from 2kg. to 200kg. that were dropped in the water during WWII. They were dropped because planes carrying bombs that were not used on targets could not land with them, for fear that if the landing failed, the bombs would damage or destroy the airfield. So when returning with unused bombs, pilots would just drop them in the sea. But now, as human enterprises move offshore, all of these bombs pose a hazard. This is particularly exacerbated with the development of offshore windfarms. And of course just blowing them all up just defers the damage left over from the war – with heavy consequences on marine life.

A joint project by Loughborough University, the UK National Physics Lab, and Arhaus University has developed a “deflagration” protocol whereby a hole is drilled into the bombs, and the contents are set on fire, significantly stretching out the time that the explosive energy of the content is released. This can decrease the noise level by 20dB (1/100th of the noise) thereby significantly decreasing the acoustical damage to sea animals and their habitat.

And of course most of us would not be here without the sonar issue that came up on everyone’s screens 25 years ago, when a mass-stranding occurred while there were public hearings in the US about “Navy sonar.”

The term “Soundscape” was first introduced back in 1977 by Canadian composer R.Murray Schafer with his seminal book “The Soundscape: Our sonic environment and the tuning of the world.” Schafer couches his argument in the toxicity of chaotic sound environments from a human perceptual standpoint. But the term has since become useful in evaluating other bioacoustic settings – particularly in the sea, where it is much easier to identify things by hearing them than seeing them. The challenge is to decipher what all the sounds mean.

The inquiries were focused on instrumentation, metrics, and interpretation. Marine life density can express itself through biological sound complexity, and how industrial noise can compromise it. Coral reef recordings are being used to encourage reef animals to recruit into compromised reef areas, and elephant seals fitted with sound recorders are diving down and bringing back soundscape recordings from 1000 meters deep.

Another unfolding soundscape instrument technology is “Distributed Acoustic Sensing (DAS),” which uses the distortions wrought on fiber-optic signals from ocean sounds that impinge on them. Unlike hydrophones, which pick up sounds to a single point, fiber-optic cables can pick up sounds along the entire length. Ths means that entire ocean basin soundscapes can be accessed and modeled – within the 5kHz-and-below bandwidth of the DAS technology.

This will go far in understanding the dynamics of the soundscapes throughout the sea.