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.”

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.