Whales hear us more than we realize

May 2, 2014 |

Killer whales and other marine mammals likely hear sonar signals more than we’ve known.

That’s because commercially available sonar systems, which are designed to create signals beyond the range of hearing of such animals, also emit signals known to be within their hearing range, scientists have discovered.

The sound is likely very soft and audible only when the animals are within a few hundred meters of the source, say the authors of a new study. The signals would not cause any actual tissue damage, but it’s possible that they affect the behavior of some marine mammals, which rely heavily on sound to communicate, navigate, and find food.

The findings come from a team of researchers at the Department of Energy’s Pacific Northwest National Laboratory, working together with marine mammal expert Brandon Southall of Southall Environmental Associates. The findings were published April 15 in the journal PLOS ONE.

A team led by Zhiqun (Daniel) Deng, a chief scientist at PNNL, evaluated the signals from three commercially available sonar systems designed to transmit signals at 200 kilohertz. The impact of such systems on marine mammals is not typically analyzed because signals at 200 kilohertz can’t be heard by the animals.

The team found that while most of the energy is transmitted near the intended frequency of 200 kilohertz, some of the sound leaks out to lower frequencies within the hearing range of killer whales and other animals such as harbor porpoises, dolphins and beluga whales. The three systems studied produced signals as low as 90, 105 and 130 kilohertz.

At the levels measured, the sounds would be quieter than many other sounds in the ocean, including the sounds the animals themselves make, and they wouldn’t be heard at all by the animals beyond a few hundred meters.


“These signals are quiet, but they are audible to the animals, and they would be relatively novel since marine mammals don’t encounter many sounds in this range,” said Southall, who is the former director of the Ocean Acoustics Program of the National Oceanic and Atmospheric Administration.

“These sounds have the potential to affect animal behavior, even though the main frequency is above what they primarily hear. It may be that environmental assessments should include the effects of these systems. This may not be a major issue, but it deserves further exploration,” added Southall.

The new findings have their roots in a project to track marine mammals in Puget Sound, which was part of a broader effort to provide information on the environmental impact of a planned tidal energy project there near Seattle. Researchers had planned to use sonar to help locate killer whales, but some marine mammal experts had observed that the animals might actually be hearing the sonar. Those observations led to the study, which was funded by Depart of Energy’s Office of Energy Efficiency and Renewable Energy.

How do the sonar signals actually sound to marine mammals like killer whales? Since high-frequency sonar pings several times per second, it’s possible that it sounds like one continuous, high-pitched hum or ping.

“If you think of a keyboard on a piano, the ships would be hitting the low notes quite hard, the middle keys would be most of the sounds of the animals themselves, and the sonar systems we studied would be relatively quieter sounds in the top few octaves on the right of the keyboard,” said Southall.

The authors of the paper did not directly study the hearing capability of whales and other marine mammals. Instead, the study focused on the sounds produced by sonar systems, discovering that commercial sonar systems are emitting signals within the animals’ known hearing range. Deng and colleagues are currently considering ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals.

42 Responses to Whales hear us more than we realize

  1. u14084351 May 7, 2014 at 12:42 pm #

    It is remarkable how sonar works. It is old news that whales use sonar signals to find food, communicate with their families and navigate. The sonar is simply an echo like when your voice echoes back from a gorge. The whale sends these sound waves into their surroundings which in return bounce off from nearby objects and is reflected back to the whale. The article only proves that whales and other marine animals can be harmed by sonar signals created by man because it intervene white their own signals. This interference can be harmful to the whales and other marine life.

  2. u14060893 May 7, 2014 at 2:51 am #

    This article actually reveals no new information, it was always believed that aquatic mammals are influenced by the sonar created by human activities. It has been seen in the behavioural change of these animals over the last few years. It is time that animal rights groups actually try and lower the impact of human activity on wildlife and everyone can comment saying “humans should stop putting themselves first” or “something needs to be done” but the sad truth is that the people in power are power-hungry, greedy and for those individuals the deaths of a few animals is justified through the benefits they reap. One only has to look at the situation in the U.S Where Obama has given out 30-year killing permits of Golden and Bald Eagles to certain wind-farm owners, just because they want to build turbines in their territories! The fact of the matter is as follows: we can not expect change if WE don’t get up and do something to change how high-ranking individuals treat the environment we live in.

  3. 14353262 May 5, 2014 at 10:58 pm #

    I absolutely love whales’ and all other marine life, and believe that further investigation is needed to ensure the safekeeping of these magnificent creatures. Studies should be made to determine the hearing capability of all sea animals so that they would not be desturbed in their habitat.

  4. 14107822 May 5, 2014 at 6:37 am #

    In an article titled “Sonar does affect whales, military report confirms” by Daniel Cressy it is stated that “Beaked whale species… appear to cease vocalizing and foraging for food in the area around active sonar transmissions”. According to the article “second and third-order affects could include starvation and then death, depending on the severity of the sonar’s initial affect on the whales”.
    This might be called “noise pollution” and will make for further interesting research regarding ways to minimize risk of noise pollution or as the article stated “ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals .”

  5. Joseph u14170796 May 5, 2014 at 4:10 am #

    I think scientists should study about the hearing capability of whales and other marine animals, this will help to find the solutions on how to stop disturbing such animals especially those which rely heavily on sound to communicate, navigate, and find food.
    It seems as people are now the disturbance of marine life. Whales and other marine animals are very important so we protect them.I believe this posts will encourage many scientist to study more about hearing range of many animals.

  6. u14043892 May 5, 2014 at 12:46 am #

    Sonar systems on broader spectrum, relates to super ultra sounds. It opens up a whole world to discover. On the field of marine biology, we can determine a lot of things, we can also determine distances, and classify a lot of marines animals…as we know marines animals have a very sensitive hearing, and can hear at very low frequencies. Sometimes sounds that we create can be disturbing to sea animals, and can be dangerous to there hearing tissue… Communication can also be difficult, if there is sounds at the same frequencies in the water… So we must be very carefull for ultra sounds that we create on the sea water… If we look at some land mamals, the elephant also communicates at very low frequencies, somlow that the human ear cant hear it… We use sonar for a lot of things, in the medical world we use sonar to classify, fetus growth, fractures and variable other things…Sonar is probably, the most common thing, that is very important to us……

  7. 14009863 May 5, 2014 at 12:11 am #

    The fact that marine mammals can hear these sonar signals is quite concerning. If it is in fact true, then this means that these mammals are being disturbed by the sounds emitted by sonar systems. This can pose to be a huge problem as we are disturbing these mammals in their natural habitat. Hunting and communication play a big role in these mammals’ lives, especially the killer whales who predominantly use sound and vibrations to survive. When these ways of communication are disrupted, the whales become confused and terrible things such as separation and even death may occur. The research into reducing the amount of signal leakage is extremely important because our marine life is suffering in the mean time. Hopefully they can find ways to reduce the signal leakage, thereby preventing the worsening of our seas and the mammals within it.

  8. naidoo MM (14142296) May 4, 2014 at 11:12 pm #

    These marine aminals rely on their hearing to direct their whereabouts. If these ships or human-caused sounds give off these high frequencies, this can have a negative effect on our aquatic mamals. We can not ignore these mamals just for human expansions. We need to consider there exsistence. If we dont protect them then who will ?

  9. MZT 14132096 May 4, 2014 at 9:55 pm #

    I must agree with a previous comment whereby it was stated that human intervention into mother nature is rather excessive and concerning. In this article it is not very informative as to how the whales are affected by all these sonar signals. The disturbance of marine life with man made machinery is vast and the effects towards marine life have not been entirely taken into account. I feel methods must be taken to ensure the safety and health of marine life. For example forming marine area reserves and enforcing restrictions on the frequency and wavelengths on these sonar waves which affect the natural world.

  10. Mick Taylor May 4, 2014 at 1:59 pm #

    The human intervention into the lives of nature and the wilderness is a concerning issue. Having technology that can possibly alter to behaviour of marine animals in the wild should be alerting and surelynsomeone should research this and find an alternative route. They were here long before us and we’re just guests on this planet. If these signals interfere with animals that rely heavily on ecolocation to navigate, communicate and hunt food… what are we doing to their natural primitive behaviour?

  11. u14029414 May 4, 2014 at 12:40 pm #

    Sonar sounds do not just affect marine animals like whales it also irritates the hearing of polar bears in the northern pole. Sometimes these bears even kill people in the surrounding area out of their frustration.

  12. 14119294 May 4, 2014 at 11:16 am #

    This should be concerned. I also believe that marine life has disturbing by our new technology.

  13. malike 13352378 May 4, 2014 at 10:44 am #

    Technology should be the reason to the disturbance of marine or wildlife as whole humans should stop putting themselves first and look at the world around as and make it better both technologically and ecologically

  14. Spha.u14307104 May 4, 2014 at 9:14 am #

    its arguable , only when under water, that is were they are fluent.

  15. Liezl van Niekerk (u14114683) May 4, 2014 at 8:18 am #

    This matter is very concerning. As a Scuba diver, I believe that our new technology should be developed in such a way so as to not disturb our marine life. I believe that scientists should make a genuine effort to develop technology that won’t have an effect on marine life as it will also influence the outcome of research by influencing the animal’s behaviour. Thus I agree with my peers in saying that we should do everything in our power to either lower the amount of sound waves that escape into the ocean or lower it to a lower frequency so it can’t be heard.

  16. A Oberholzer (u14025842) May 4, 2014 at 7:53 am #

    We can’t destroy these animals’ hearing, by using, like Demi Schoeman mentioned, human-caused sound waves. Scientists have to
    consider ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals.

  17. Tim Hardwick (u14013267) May 4, 2014 at 7:26 am #

    Man’s affect on nature and its far reaching impacts can be seen in so many areas. This shows that this new information on how sonar may effect marine mammals must be taken seriously, as it could have impacts far beyond anything foreseeable. This phenomenon must be investigated, but in a safe and isolate manner so that it would not harm any wild marine mammals or their surrounding environment. It is also a great and new way to study the behaviourism of animals and how dependent these creatures are on their ability to communicate via sound.

  18. kabelo(14042917) May 4, 2014 at 6:53 am #

    I agree with Serlien.Whales are then very important animals to protect.Such matters must be researched to find if they might lead to extinction of marine animals.

  19. kabelo(14042917) May 4, 2014 at 6:22 am #


  20. Demi Schoeman (14031699) May 4, 2014 at 4:28 am #

    As mentioned in the article, whales and other marine mammals rely on their hearing for life’s most basic functions including communication, navigation and finding food. So when an extremely powerful human-caused sound such as ships emitting sonar fills their ears, the results may be devastating. Perhaps, this is because the human-caused sound waves drown out the noises that marine mammals rely on for their survival? Thus, research and extensive mitigation methods should be carried out to ensure the protection and existence of our marine mammals.

  21. u14140757 May 4, 2014 at 1:57 am #


  22. Tanya Strydom (14104262) May 3, 2014 at 9:27 pm #

    I must agree with Manakana Kamogelo (u14027110). They should think about studying the hearing range of marine mammals and determine which frequencies would fall within their range and then tackle the issue of limiting signal leakage to fall outside their hearing range. It would probably be quite difficult to study the effect of the sonar on their behavior with these species because are they not naturally curious and would want to investigate this strange new sound? It would be quite an interesting study to execute.

  23. u14126037 May 3, 2014 at 1:40 pm #

    This is quiet amazing!
    I can relate to it as i have been in to multiple marine trips and heard about the Whales marvelous communication skills and use of Sonar. However i wanted you to elaborate slightly more in the generation of the sonar signals. How are they generated exactly?
    As for commenter ( Mihlalikazi 14103002 ) I believe i can answer you last question.
    The main purpose for sonar signals generated by whales is to detect nearby environment, more of seeing, and warning them by possible obstacles. in addition it is thought that they resemble a method of communication among whales.
    Does the fact that Whales respond to sonar signals trigger any future possibility of communicating with other marine life?

  24. John Davidson May 3, 2014 at 1:28 pm #

    While it may not come as a surprise that marine mammals communicate by sonar, it is definitely something that we must take into consideration when dealing with the ways in which we communicate or share information at sea; things such as how ships or submarines may communicate with one another, or using sonar technology to detect weather in surrounding areas.

    Seeing as these mammals rely on sonar to communicate as well as find prey, any sonar signals which we produce ourselves may very well have adverse effects on the animals. This could be potentially made worse if the signals we produce are constantly present for the animals to hear. Behavioral alterations, as well as possible effects on the animals ability to catch prey, may have very negative effects on the animals affected, and possibly their species as a whole.

    It is definitely worth continuing the studies of the effects our own sonar signals may have on the surrounding marine wildlife, as it may have more detrimental effects than w ever imagined


    John Davidson

  25. HyeJin (14298458) May 3, 2014 at 12:35 pm #

    As the article mentions,marine animals, such as dolphins and whales, use echolocationto to locate predators and prey, to communicate and to navigate thier path ways. Thus, I agree that it is a big issue to acknowledge that some of our sonar systems are creating sounds that are intefering with the sound range of these marine animals. As a good example, Fabian Henley (above comment) mentioned that in March 2009, 200 whales were beached on one of the beaches in Australia due to this problem. To maintain our marine life cycle, I personally think it is necessary to quickly bring about a plan to repair the sonar systems to emmit only the sound with a frequency that is high enough that will not affect any marine life in any way.

    Additionally, I researched some information and found that study has shown whales experience decompression sickness, a disease that forces nitrogen into gas bubbles in the tissues and is caused by rapid and prolonged surfacing. Although whales were originally thought to be immune to this disease, sonar has been implicated in causing behavioral changes that can lead to decompression sickness. Meaning the sonar systems may also cause diseases and sickness to our marine life animals. I think we need to take this problem more seriously and protect the animals from various attacks they may be experiencing through humans.

  26. Josef Grobler (u14028052) May 3, 2014 at 10:24 am #

    This is true that the sonar affect marine mammals, because when a ship or boat uses sonar and there are marine mammals near they tend to swim away. This is because, what is said in this blog, the sonar may affect them negatively. This blog has given me the insight to understand a little bit of how sonar affects marine mammals and how they might hear these sounds. This blog also makes it available to further study and understand how marine mammals’ hearing works, what frequencies they can hear and what frequencies they operate on.

  27. 14073600 May 3, 2014 at 9:41 am #

    If these solar signals can in fact be picked up by mammals such as whales, is it worth spending large amounts of time, money and research resolving this problem? There are countless other animals which suffer in ways much worse than whales picking up stray solar signals projected by us. If the problem does prove to be fatal to the whales I can not see why this problem should rather be addressed than other, more important situations.

  28. Fabian Henley (14092370) May 3, 2014 at 8:45 am #

    To understand the relationship between sonar and whales, dolphins, or porpoises, one has to know that these marine animals have quite a good vision (depending on the species you’re looking at). However, beneath the surface of water, their vision does become slightly impaired due to light rays being refracted by the waves on the surface. This is where sonar comes into play…a whale in this case, emits its own sound waves -sonar- at a certain frequency. the sound waves are then reflected off an object and return to a receptive organ in the whale, thus, the whale is able to visualise prey, and its surrounding environment from a further distance.

    How does the sonar affect the whales? Well, basically the sound waves emitted by the ships are at a higher frequency than the sound waves emitted by the whales. These sonar waves produced from the ships interfere with the sonar waves of the whales, and hence, the whales are unable to detect their surroundings before it’s too late. For example, in March 2009, 200 whales were beached on one of the beaches in Australia whereas on the odd occasion you would get one beached whale. Many people were left baffled about the drastic occurrence, and some had even believed that this was a symbol of “doomsday” approaching. After much research, scientists had discovered that these whales were migrating as a pod, when a ship nearby emitting sound waves had interrupted with the whales’ sonar. The whales were then lost from their normal travelling field and before they could realise it, they were already too close to the shore to turn back, and as a result, they had become beached.

  29. Sarlien u14035783 May 3, 2014 at 8:20 am #

    This blog opened up a whole new perspective for me towards the way that we communicate with sonar systems and that not enough research has been done to know the full affects it has on the marine mammals. I would like to know from what distance these sound leaks would be audible to the marine mammals and if they would affect them in any negative way ? I think it is important that further research should be done to know more and to know the true affects these sonar systems have on the marine mammals.

  30. 14078041 May 3, 2014 at 7:18 am #

    It would be interesting to know what the direct results and affects of these sonar signals on the marine animals behaviour. Are there any specic behavioural abnormalities that have been encountered? If so what have the researchers observed?

    I am also interested in finding out how the researchers are going about finding out about the affects of sonar on the marine animals. Is there any insight you could give me regarding the process they may follow?

  31. Mberipura Tjijorokisa (u14048452) May 3, 2014 at 5:19 am #

    The article mentions that the sonar systems may effect the behavioral patterns of the killer whales. How sure are scientist that the sonar systems will not cause catastrophic damage to not only the killer whales but also so other marine life? What tests have been conducted to reassure us that the sonar signals will not cause any tissue damage to the killer whales? It is evident that the short and long term edicts of the sonar signals on marine life is a field that requires much more attention and research.

  32. Amore Jacobs (14228093) May 3, 2014 at 3:06 am #

    What are the actual impacts that sonar signals have on the behavior of these animals?

    We have been using sonars dating as far back as World War 1, could it not be possible that whales have adapted in such a way that these leaked signals do not have an effect on them anymore?

    i agree with the comment that Jason Bell (14036194) made, that the hearing capabilities of these animals should be studied to help better our knowledge as to what extent these animals are effected, if they have not adapted and whether sonars can be bettered to diminish these impacts as far as possible.

  33. 14048371 May 3, 2014 at 1:08 am #

    What i would like to know is what could possibly be done if these researchers realize that these sounds do affect the behavior of these animals? would the have to develop a new kind of technology? Or possibly move them further away so they wont be picked up by these animals? Something else that is bothering me is should they do anything about these sonar pieces?I mean these sounds could have been present for the animals for a long time, even though we only just realized that the animals could hear them. What if the animals have become so used to it that they don’t even notice it anymore? I think the researchers should first determine how long these animals have heard these sounds, and whether they are truly affected by them, before they decide to make any drastic changes.

  34. Robyn (14110352) May 3, 2014 at 12:52 am #

    What really perplexes me is how little we about how our technology affects the things around us. For how many years have we been using sonar and its effects on animals are only coming to light now? What other animals are we driving crazy with our technology, i mean more research needs to be done in this sort of field.
    I’m really confused about how the sonar leas frequencies that these marine animals can hear? I mean like the others have said surely it messes with their internal navigation to find one another and food?
    Why is sonar still the best method to cooperate though surely their are more efficient means with all the technological advancements that have been made?

  35. Jason Bell (14036194) May 2, 2014 at 10:09 pm #

    I found this article to be quite interesting, but I think if they really want to know if certain marine animals can in fact hear sonar then they should study the hearing capabilities of these marine animals. This will help them understand marine animals better but it might also help better our use of sonar because we will try to get the signals not to be heard by any animals. But how would sonar signals affect the behavior of some animals that hear it?

  36. vAs May 2, 2014 at 9:49 pm #


  37. Jas (14123437) May 2, 2014 at 12:23 pm #

    How exactly do these leaked sonar signals affect the whales themselves? Does it disorientate them?

    The main concern is that these leaked sonar waves can be detrimental to the animals which it affects. The problem here lies in the fact that the animals could be harmed by disorientation or caused distress by unfamiliar sounds, not that research will be hindered. These sound leakages are understandable, as one cannot think to effortlessly control the activity of microscopic sound waves, but what exactly can be done to stop these leakages?

  38. Jessica u14007348 May 2, 2014 at 11:10 am #

    As mentioned in the article the sounds emitted by the sonar are quieter than the sounds the animals actually make but is there any possibility that the marine mammal’s prey emit sounds at the same frequency as the sonar? If not in what way does the sonar affect the marine mammals? Is it perhaps better if the sound is left to leak out so that whales and other marine mammals can recognize areas where sound is released at such a variety of frequencies? If this is allowed to happen over several years the behavior of these animals may change to the extent that they avoid areas where there are sonars and ultimately to avoid areas where there are boats and human beings which pose a great danger to these animals.

  39. u14100712 May 2, 2014 at 10:34 am #

    This blog sparks much thought on the possibility that marine mammals’ behaviour could actually be influenced by sonar signals.The longterm effects of the signals on marine-life is definitely a field that requires study. It could be that marine mammals have been acting on these signals, leading to the disruption of nature. If this is true, it will cause great controversy between people fighting for marine life and people in control of the sonar systems. This might lead to the possibility of new technology and the improvement of sonar systems to reduce the frequency of the signals.

    Referring to the post made by Mihlalikazi 14103002, sonar is a technique in which sound is used to navigate, communicate with or detect objects. It is typically used by submarines or ships to detect vessels etc. It is highly common and would not easily be replaced if it had to be limited by studies proving it’s effect on marine life.

  40. Manakana Kamogelo (u14027110) May 2, 2014 at 9:17 am #

    Since killer whales and other marine mammals are able to hear signals of sonar systems then they cannot be traced. The effect of sound emitted by sonar system on marine mammals’ behaviour needs to be investigated further because it is said that the sound has potential to affect their behaviour even though the main frequency is above what they primarily hear. Might be helpful if the authors of the paper directly study the hearing capability of whales and other marine mammals and not focus only on sounds produced by sonar systems. before they work on finding ways to limit signal leakage. Because marine mammals that can hear sonar sounds are the ones which depends on sounds to communicate, navigate and find food.

  41. Manakana Kamogelo (u14027110) May 2, 2014 at 8:43 am #

    Since killer whales and other marine mammals are able to hear signals of sonar systems then they can not be traced. The effect of sound emitted by sonar system on marine mammals’ behaviour needs to be investigated further because it is said that the sound has potential to affect their behaviour even though the main frequency is above what they primarily hear. Might be helpful if the authors of the paper directly study the hearing capability of whales and other marine mammals and not focus only on sounds produced by sonar systems. before they work on finding ways to limit signal leakage. Because marine mammals that can hear sonar sounds are the ones which depends on sounds to communicate, navigate and find food.

  42. Mihlalikazi 14103002 May 2, 2014 at 7:34 am #

    How exactly do this sonar signals work?does it mean Whales hear us when we talk?or does it mean Whales hear when they are in danger through the sonar signal?Whats actually the main purpose of the sonar signal?

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