Seismic Surveys & Airguns
A seismic survey is conducted when compressed air streams or focused sonic waves are sent towards the ocean floor in order to gauge the depth, location and structure of the valuable geophysical resources that lie underneath. Scientists confirm that seismic surveys increase noise levels to twice the normal level and impact marine life by disturbing their habits essential for survival. One of the biggest culprits of underwater noise is the technique used during seismic surveys to prospect for oil and gas offshore. Companies use high-volume air guns that are so loud, you can see the water rise and fall when the guns go off. The devices, towed behind vessels that trace grids on the ocean surface, emit blasts of compressed air that both energy companies and conservationists acknowledge are at least as loud as a roaring jet engine. The use of airguns unavoidably results in noise pollution in the surrounding area. The acoustic impacts on marine mammals associated with seismic surveys for oil & gas can be reduced if frequently mitigated with the use of passive acoustics. To ensure that marine mammals are not harmed when in the close vicinity of these activities, regulatory authorities request so-called mitigation measures for their protection. One of such measures requires airguns to be switched off when whales approach the respective sound source too closely.
Pipeline Leak Detection
Hydrophones can be used as acoustic leak detectors because they identify the sound or vibration induced by water escaping from pipelines under pressure. When pressurized water leaks from a pipe it creates a sound or an acoustic signal that can travel through both the pipe wall and the water column in the pipeline. Most of the existing acoustic leak-detection techniques rely on external measurements of sound emitted from the turbulent jet of water escaping the pipe.
Machine Health Monitoring
Hydrophones can be used to monitor the health of underwater machinery. Attaching a hydrophone is not only beneficial for monitoring the health of the machine, but also for the operator as the hydrophone becomes an additional sensor. The hydrophone as a sensor can help provide direction as sound will indicate when the operator has run the machine into an object underwater and has to manoeuvre around it.
“Ocean Networks Canada performed a wide range of tests on the hydrophones prior to deployment to verify the manufacturer’s specifications. The hydrophone instruments met all the manufacturer’s specifications and were easy to use. Both models satisfy our requirements for dynamic range, sensitivity and, most importantly, reliability. When coupled with the fast and friendly customer support we have received, these LF and HF hydrophones are a good choice for our ocean observatory.”Tom Dakin Sensor and Technology Business Development Officer and Resident Ocean Acoustician Ocean Networks Canada
“We have been working with Ocean Sonics in our technology demonstration program since the first prototypes. Our science users have been very impressed with the very high quality data sets. Ocean Networks Canada is expanding our hydrophone network with Ocean Sonic icListen HF smart hydrophones across our observatory including new sites across coastal BC, as part of the Smart Oceans™ program. The compact size, Ethernet interface, high reliability and exceptional performance make these systems ideal for ocean observing applications such as mammal classification, vessel and ambient noise studies.”Scott McLean Director(Former) Ocean Networks Canada
“I have used many different hydrophones on different systems, but these icListen hydrophones are the best I’ve seen in many years. They’re calibrated to very low frequencies where I’ve never been able to get reliable data.”
Ross Chapman Professor Emeritus University of Victoria
The Ocean Observatories Initiative (OOI) Regional Scaled Nodes (RSN) had requirements for very broadband hydrophones with good noise floor characteristics and a wide dynamic range. The icListen HF hydrophones satisfied these requirements at a reasonable cost. The hydrophones were quite easy to use out of the box, and easily passed our intensive First Article tests centered on assuring any instrument will not interfere with or corrode any other instrument. Customer support has been quite good, with very detailed questions answered quickly and accurately.
Skip Denny Principal Ocean Engineer, RSN Applied Physics Lab, University of Washington.