Underwater Internet of Things: Industrial boon, biological headache
Michael Stocker – mstocker@OCR.org
Bluesky: @ocean-noise.bsky.social
Instagram: @oceanconservationresearch
PO Box 559, Lagunitas, CA, 94938-0559, United States
Popular version of 4aAB9 – Underwater Internet of Things: Industrial boon, biological headache.
Presented at the 188th ASA Meeting
Read the abstract at https://eppro01.ativ.me/appinfo.php?page=Session&project=ASAICA25&id=3864158&server=eppro01.ativ.me
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
As the technologies of commerce and industry expand out into the sea, so does the need to localize, query, and control these technologies. Due to the challenges of physically accessing underwater equipment, a digital “Underwater Internet of Things” is being developed for marine enterprises.
Due to the opacity of water to radio frequency electromagnetic energy – which we use for our above water WiFi and Blue Tooth and other communication connections, underwater communication channels predominantly use sound. This is particularly the case as distances between the communication nodes increase.
Seafloor processing equipment for oil and gas extraction equipment (Nautronix illustration)
The efficiency of sound transmission through water has not been lost on evolution; pretty much all marine and aquatic animals use sound to get around. From the simple clicks and grunts of marine invertebrates and fishes, to the complex and beautiful songs of humpback whales. In fact sound transmits so efficiently in water that some whales can project sounds over thousands of kilometers.
The ocean is alive with sound, and marine animals have evolved and adapted to utilize “acoustical niches” appropriate to their particular habitats; dolphins using high-frequency, short wavelength biosonar for near-field echolocation, large whales using low-frequency, long wavelength sounds for long distance communication and navigation. And all the critters in between – fishes, lobsters, krill, and benthic worms, all have their own habitat-adapted sound repertoires.
So herein lies the conflict with the acoustic Underwater Internet of Things (UIoT): The frequencies of the sounds being used to control and query underwater equipment overlaps the various existing bioacoustic communication channels. And while the sheer density of this technological noise threatens to obscure or “mask” important bioacoustic communication channels, the sound qualities of the common digital signals themselves threaten to turn the ocean acoustic environment into a living acoustical nightmare.
Digital communication hinges on unambiguous data states – strings of “ones and zeros” that code into data channels. Acoustically this translates into ripping streams of “noise-not noise” signals. The problem with this in the realm of bioacoustics is that these data streams sound horrible. They are also clearly associated with hearing damage in humans and other animals.
(Samples of some underwater digital communication signals: https://ocr.org/sounds/underwater-communication-signals/?portfolioCats=200%2C201)
This nasty noise problem is exacerbated by the fact that the most useful transmission frequencies for commerce and industry fall in the 1kHz to 50kHz frequency range, which resides in the ‘sweet spot’ for dolphins and porpoises, and overlaps the hearing ranges of most other marine animals.
Working with the International Standards Organization (ISO) and the International Electrotechnical Commission (IEC), we are urging industry to use signals that are less damaging to marine life. This would include “transmit on query only” and synchronized, spread spectrum “frequency hopping” schemes,* and using bio-mimetic signals which would sound more like dolphins or whales and less like giant fingernails scratching across a dirty chalkboard.
* “Spread Spectrum, frequency hopping” technology was patented by 1940s-50s glamour actress Lana Turner. The premise being that the transmitter and the receiver are synchronized over a coded series of transmission channel frequencies. Transmission only occurs at a specific time over a specific frequency channel. In this way the communication channel becomes impervious to noise, so the signal level can be below the ambient noise level. A variation of this technology makes it possible to have millions of cell phones operating in the same radio frequency band without interference.