Brent Meister UR: Ocean Noise

     To start I am going to reiterate the most common themes of human generated noise pollution in the ocean. The most common human generated noise in the ocean are shipping noise, military sonar, and air-gun arrays. Most noise pollution is in the range that most humans can here so you can imagine how loud it would be if you had a shipping lane right above your house. The article goes on to explain that most toothed whales use a high frequency bio sonar , which is similar to sonar ran by military ships and is well above the human range of hearing. there was a study done off the coast of Neptune Canada. this study showed the noise rating all year long in the ocean. what they found was there was an Eco sonar used to monitor ocean currents was show in a cyan color band in between 30 Hz and 40 Hz which is just out of the range of human hearing. also the article goes on to explain that the noise can travel. as we place tags on sharks and even whales they give off the same sound as the eco sonar off the coast of Neptune Canada and can travel up to 10 kilometers (6 miles).
http://newswatch.nationalgeographic.com/2013/09/20/ultrasound-ocean-noises-pose-risk-to-marine-life/

Shark Tag

Year long ocean noise survey off Neptune Canada

Deb n' Paul
Ok--I need more elaboration on the questions you answered for me this week. Please remember--you will often times need to answer these questions to persons not at all familiar with these concepts/terms such as students in an intro oceanography class!. e.g., " The decibel value is the logarithmic ratio of the intensity of the wave to a certain reference point." followed by a link for me to continue searching for the answer. No, no, no! Again I ask--and in layman's terms--what is meant by hertz, frequency and decibel and how do they differ from one another. Also--if you are going to direct the student to more information, please help them out by giving them an example of how the information might be used or what you will be using it for. YOU do the work--that's your job! Not the job of the reader!

     To start hertz is the standard unit of frequency. Frequency is the number of cycles a wave has. if you think of a wave in the ocean you measure it from crest to crest or trough to trough. so you can say however many times you see a wave pass an end point in a certain amount of time that is the frequency of that wave. it works the same way as as if you are measuring sound because sound travels in waves and hertz is the frequency of that wave in a given time. so you can say frequency and hertz are related. a decibel simply put is how intense the wave is. you can look at it as the higher the frequency the shorter the wave length and the higher decibel rating will be. decibels are usually measured in a confined space. most of the time in the water it is up to 1 meter. so the decibel of a lighting strike is 260 dB in one meter of water. however most times you measure noise in the ocean it is almost always in hertz because it is more relate-able to the mammal hearing process.