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RESEARCH:

DolphinEar hydrophones are used by researchers all over the world - in more than 70 countries! (PhotoCredit: NASA ICE CC-BY)

BIO-MARINE INVESTIGATIONS

McGill University- Aquatic Walking Robot :

“The listening apparatus consists of four DolphinEar/PRO omni directional hydrophones, which are attached at the corners of a square buoy of size 1.0 x 1.0m, shown in Fig. 3. Sampling frequency was 44100 Hz, signal resolution 16 bits, sample size 2048 samples.”

“Acoustic Sensor Package:  The acoustic localization component consists of arrays of commercially available omni-directional hydrophones attached under a surface-floating buoy, whose absolute position can be measured via a combination of GPS, compass, inclinometers and inertial sensors. The underwater sensor unit is equipped with a transducer generating impulsive sound in the audio frequency range. Localization is carried out in two steps, (a) direction of arrival estimation at each array, and (b) estimation of the intersection of the direction lines. Time-delay estimation at each array allows the estimation of direction of arrival at that array. The minimum number of microphones required is three, leading to a system of three linear and one quadratic equation in the coordinates of the direction vector. With more than three microphones, a least mean squares approach is used.”

Underwater Robots: Here four DolphinEar PRO hydrophones are used on a test rig as part of an acoustic sensor package to be fitted on an autonomous underwater robot that is to be used to monitor habitat change as a result of global warming. Ocean acidification is a major concern as climate change intensifies and begins to threaten the marine food chain. (Photo Credit: McGill University) Shisha pipe - the Arab tobacco pipe that was once considered an good way to filter out harmful components of smoke. Research using a DolphinEar hydrophone proved otherwise. The hydrophone disc was placed underneath the water reservoir to record the bubble stream as the pipe user inhaled.

UNDERWATER ROBOTIC RESEARCH

McGill University- Aquatic Walking Robot Research

BUBBLES - Shisha Pipes and Climate Research

Oceanbubblecloud=By Duncan Rawlinson at www.thelastminuteblog.com =CC-BY-2.0= via Wikimedia Commons.jpg

Several years ago a researcher in the Middle East came to us to ask if our DolphinEar’s could hear bubbles within a shisha pipe - one of those  water pipes where tobacco is filtered through a reservoir of water before it reaches the user’s mouth. He wanted to calculate the volume of smoke and any harmful or addictive substances that reached the user. He did this by mounting the DolphinEar hydrophone disk under the base of the shisha pipe where he got excellent sound quality of the bubbles generated as the user inhales the smoke. Using the spectrogram software that comes with every DolphinEar hydrophone he was able to measure the size of the bubbles based on their pitch. From this he was able to calculate the volume and flow to give him the results he was after,  

Bubbles hold many secrets, for example, how much methane is being released from frozen methane hydrates that lie on the sea bottom. Knowing this is important to climate scientists as they try to determine at what point the release of sequestered methane might occur.  Our new DE600 wireless-ready DolphinEar opens up new possibilities for remotely monitoring these methane releases particularly along coastal areas where cellular/mobile telephone coverage makes worldwide monitoring possible. Methane hydrates can be found in every ocean and in every climate zone. Knowing where tipping points may occur as the Earth’s climate warms is one of the most important questions to what will happen in a future warming world.  Methane is a greenhouse gas which is about 23 times more potent than CO2.

Bubbles of air trapped in ice as it forms are released again as it melts. These tiny pops are analyzed by a DolphinEar hydrophone and spectrogram software to monitor the melt rate.

In the Southern US, DolphinEar is used to monitor manatee vocalisations and boat movements that have caused serious injuries to these slow swimming creatures.  


In Canada, arrays of DolphinEar hydrophones are used to study the habitat of various soniferous fish species within small bays and inlets.

And, of course, DolphinEar is widely used in the study of cetaceans around the world.  It’s also a favorite of students, university researchers and dedicated hobbyists.