What are common underwater sounds?

The ocean is filled with sound. Underwater sound is generated by a variety of natural sources, such as breaking waves, rain, and marine life. It is also generated by a variety of man-made sources, such as ships and military sonars. You can listen to examples of many undersea sounds in the Audio Gallery.

Some sounds are present more or less everywhere in the ocean all of the time. The background sound in the ocean is called ambient noise. The primary sources of ambient noise can be categorized by the frequency of the sound.

In the frequency range of 20-500 Hz, ambient noise is primarily due to noise generated by distant shipping. Even after removing any noise generated by ships close to the receiver, distant ships can be detected. The amount of noise is greater in regions with heavy shipping traffic. There tend to be fewer ships in the southern hemisphere, and low-frequency ambient noise levels are generally at least 10 dB lower as a result. Noise generated by shipping has increased as the number of ships on the high seas has increased.

In the frequency range of 500-100,000 Hz, ambient noise is mostly due to spray and bubbles associated with breaking waves. It increases with increasing wind speed.

At frequencies greater than about 100,000 Hz, the noise generated by the random motion of water molecules, called thermal noise, dominates. This noise sets the ultimate limit to the minimum sound levels that can be measured.

The background sounds in the ocean can be summarized in a graph showing typical sound levels at different frequencies. The sound levels in this graph are in dB relative to 1 µPa in a 1 Hz wide frequency band, which is usually written dB re 1 µPa2/Hz.

The typical sound levels of ocean background noises at different frequencies, as measured by Wenz (1962). This graph is therefore also referred to as the Wenz curves. The sound levels are given in underwater dB summed over 1 Hz wide frequency bands, which is often written as dB re 1 µPa2/Hz. Adapted (after National Research Council, 2003) from Wenz, G. M. (1962). Acoustic ambient noise in the ocean: Spectra and sources. The Journal of the Acoustical Society of America, 34(12), 1936–1956. Copyright Acoustical Society of America, reprinted with permission.

History of Ambient Noise Research

Noise that interfered with the ability to hear underwater sounds had been a problem since the early 1900s when the Submarine Signal Company

German contact mine placed in Australian waters during World War II. Photo by the Australian War Memorial (www.awm.gov.au).

first installed underwater bells near lighthouses to warn mariners of navigational hazards. However, the systematic study of ambient noise did not begin until World War II. During WWII, acoustic mines were developed that were triggered by the sound of a passing ship. Accurate knowledge of ambient noise levels was needed in order to set the sound levels at which acoustic mines would be triggered, so that they would explode only when a ship was present. This need helped stimulate development of the calibrated receiving systems needed to measure ambient noise levels. Under the direction of Vern Knudsen, the director of the University of California Division of War Research, ambient noise measurements were made in coastal waters and harbors for frequencies from 1000 Hz to 50,000 Hz. They found that the noise level increases with increasing wind speed and wave height. For a given wind speed, the noise level decreases with increasing acoustic frequency. The curves summarizing their results became known as the “Knudsen curves”.

The dependence of ambient noise on wind speed at frequencies between roughly 1000 Hz and 50,000 Hz implied that measurements of ambient noise might be used as a tool to determine wind speed over the ocean. This principle was exploited many years later in oceanographic instruments given the name WOTAN, for “Wind Observations Through Ambient Noise.”

Unlike ambient noise discussed above, which is almost always present, some sounds are intermittent or only occur in limited regions of the ocean. There are a large number of intermittent sources of sound in the ocean, including natural physical processes, marine life, and man-made sources.

Please review the advanced topic on ocean noise budgets to learn more about the contributions of these underwater sound sources.

Natural Physical Processes

Physical processes that intermittently generate sound in the ocean include rain, cracking sea ice, undersea earthquakes, and eruptions from undersea volcanoes. A common occurrence, such as heavy rain, can increase noise levels from those created by bubbles and spray by up to 35 underwater dB across a broad range of frequencies extending from several hundred hertz to greater than 20,000 Hz.

Marine Life

The sounds produced by marine animals are many and varied. Marine mammals, such as blue whales and harbor porpoise, produce sounds over a wide frequency range, from less than 10 Hz to over 100,000 Hz, depending on the species of marine mammal. Many fishes, such as the oyster toadfish and plainfin midshipman, and some marine invertebrates, such as snapping shrimp, also produce sounds. Examples of these marine animal sounds can be heard in the Audio Gallery.

Marine animals use sound to obtain detailed information about their surroundings. They rely on sound to communicate, navigate, and feed. Marine mammals, such as dolphins, use sound to locate and identify objects such as food, obstacles, and other whales. By emitting clicks, or short pulses of sound, and listening to the echo, dolphins can detect individual prey and navigate around objects underwater.

Marine mammal calls can actually increase ambient noise levels by 20-25 underwater dB in some locations at certain times of year. Blue and fin whales produce low-frequency moans at frequencies of 10-25 Hz with estimated source levels of up to 190 underwater dB at 1 m. The ambient noise levels at frequencies of 17-20 Hz increase off coastal California during the fall and winter months due to blue and fin whale calls.

Spectrogram from a receiver on the continental slope off Point Sur, California, from January 1995 to January 2001,using 1-day averages. The increase in ambient noise at 17–20 Hertz during the fall and winter is due to blue and fin whale calls. (Reprinted with permission from Andrew et al. 2002.)

Snapping shrimp inhabit shallow tropical and semi-tropical waters having a bottom of rock, shell, or weed that offers the animals some concealment. Colonies of snapping shrimp generate sounds with the most energy at frequencies of 2-5 kHz. Individual snaps can have peak-to-peak pressure source levels as high as 189 underwater dB at 1 m. Sound generated by colonies of snapping shrimp can dominate other sources of background noise in shallow tropical waters.

It is likely that many more species of marine life make and use sounds than we currently know.

The source levels for some sounds generated by marine life are given in the following table. The source levels of sound producers are given in underwater dB at 1m. Source levels are defined as if the receiver was one meter from the sound source. Sound levels decrease as sound travels away from the source. These are broadband source levels, which mean that they are the sum of the acoustic energy over all of the frequencies generated by the source. The sound levels given in the graph above are ambient noise levels in a 1Hz wide bandwidth, meaning that the acoustic energy was only summed over 1Hz. Because of this difference, they are therefore not directly comparable with the source levels given in the following table.

Source Broadband Source Level
(underwater dB at 1 m)
Sperm Whale Clicks[1]Møhl, B., Wahlberg, M., Madsen, P. T., Miller, L. A., & Surlykke, A. (2000). Sperm whale clicks: Directionality and source level revisited. The Journal of the Acoustical Society of America, 107(1), 638–648. https://doi.org/10.1121/1.428329[2]Watkins, W. A. (1980). Acoustics and the Behavior of Sperm Whales. In R.-G. Busnel & J. F. Fish (Eds.), Animal Sonar Systems (pp. 283–290). Boston, MA: Springer US. https://doi.org/10.1007/978-1-4684-7254-7_11[3]Levenson, C. (1974). Source level and bistatic target strength of the sperm whale ( Physeter catodon ) measured from an oceanographic aircraft. The Journal of the Acoustical Society of America, 55(5), 1100–1103. https://doi.org/10.1121/1.1914660[4]Watkins, W. A., & Schevill, W. E. (1977). Sperm whale codas. The Journal of the Acoustical Society of America, 62(6), 1485. https://doi.org/10.1121/1.381678 163 – 223
Spinner Dolphin Pulse Bursts[5]Norris, S. (1994). The Hawaiian Spinner Dolphin. Univ of California Press. 108-115
Bottlenose Dolphin Whistles[6]Richardson, W. J., Green, C. R., Malme, C. I. J., & Thomson, D. H. (1995). Marine Mammals and Noise. San Diego: Academic Press. 125-173
Fin Whale Moans[7]Cummings, W. C., & Thompson, P. O. (1994). Characteristics and seasons of blue and finback whale sounds along the U.S. west coast as recorded at SOSUS stations. The Journal of the Acoustical Society of America, 95(5), 2853–2853. https://doi.org/10.1121/1.409514[8]Watkins, W. A., Tyack, P., Moore, K. E., & Bird, J. E. (1987). The 20‐Hz signals of finback whales ( Balaenoptera physalus ). The Journal of the Acoustical Society of America, 82(6), 1901–1912. https://doi.org/10.1121/1.395685[9]Edds, P. L. (1988). Characteristics of finback balaenoptera physalus vocalizations in the St. Lawrence estuary. Bioacoustics, 1(2–3), 131–149. https://doi.org/10.1080/09524622.1988.9753087[10]Watkins, W. A. (1981). Activities and underwater sounds of fin whales (Balaenoptera Physalus). Scientific Reports of the Whales Research Institute (Japan), 83–117. 155 – 186
Blue Whale Moans[11]Stafford, K. M., Fox, C. G., & Mate, B. R. (1994). Acoustic detection and location of blue whales ( Balaenoptera musculus) from SOSUS data by matched filtering. The Journal of the Acoustical Society of America, 96(5), 3250–3251. https://doi.org/10.1121/1.411056[12]Edds-Walton, P. L. (1997). Acoustic communication signals of mysticete whales. Bioacoustics, 8(1–2), 47–60. https://doi.org/10.1080/09524622.1997.9753353[13]Aroyan, J. L., McDonald, M. A., Webb, S. C., Hildebrand, J. A., Clark, D., Laitman, J. T., & Reidenberg, J. S. (2000). Acoustic Models of Sound Production and Propagation. In W. W. L. Au, R. R. Fay, & A. N. Popper (Eds.), Hearing by Whales and Dolphins (pp. 409–469). New York, NY: Springer New York. https://doi.org/10.1007/978-1-4612-1150-1_10 155 – 188
Gray Whale Moans[14]Swartz, S. L., & Cummings, W. C. (1978). Gray whales, Eschrichtius robustus in Laguna San Ignacio, Baja California, Mexico Prepared by San Diego Natural History Museum for U.S. Marine Mammal Commission, Washington, D.C.[15]Fish, J. F., Sumich, J. L., & Lingle, G. L. (1974). Sounds Produced by the Gray Whale, Eschrichtius Robustus. Marine Fisheries Review, 36(4), 38–45.[16]Cummings, W. C., Thompson, P. O., & Cook, R. (1968). Underwater sounds of migrating gray whales, Eschrichtius glaucus (Cope). The Journal of the Acoustical Society of America, 44(5), 1278–1281. https://doi.org/10.1121/1.1911259 142 – 185
Bowhead Whale Tonals, Moans and Song[17]Ljungblad, D. K., Thompson, P. O., & Moore, S. E. (1982). Underwater sounds recorded from migrating bowhead whales, Balaena mysticetus, in 1979. The Journal of the Acoustical Society of America, 71(2), 477–482. https://doi.org/10.1121/1.387419[18]Cummings, W. C., & Holliday, D. V. (1987). Sounds and source levels from bowhead whales off Pt. Barrow, Alaska. The Journal of the Acoustical Society of America, 82(3), 814–821. https://doi.org/10.1121/1.395279[19]Wursig, B. and C. W. Clark. (1993). Behavior. in J. J. Burns, J. J. Montague, and C. J. Cowles, editors. The Bowhead Whale. Society of Marine Mammalogy. 128 – 189
Humpback Whale Song[20]Frankle, A. S. (1994). Acoustic and Visual Tracking Reveals Distribution, Song Variability and Social Roles of Humpback Whales in Hawaiian waters.(Megaptera Novaeangliae) (p. 142). Manoa HI: University of Hawaii.[21]Payne, K., & Payne, R. (2010). Large scale changes over 19 years in songs of humpback whales in Bermuda. Zeitschrift Für Tierpsychologie, 68(2), 89–114. https://doi.org/10.1111/j.1439-0310.1985.tb00118.x[22]Thompson, T. J., Winn, H. E., & Perkins, P. J. (1979). Mysticete Sounds. In H. E. Winn & B. L. Olla (Eds.), Behavior of Marine Animals: Current Perspectives in Research (pp. 403–431). Boston, MA: Springer US. https://doi.org/10.1007/978-1-4684-2985-5_12 144 – 174
Humpback Whale Fluke and Flipper Slap[23]Thompson, P. O., Cummings, W. C., & Ha, S. J. (1986). Sounds, source levels, and associated behavior of humpback whales, Southeast Alaska. The Journal of the Acoustical Society of America, 80(3), 735–740. https://doi.org/10.1121/1.393947 183 – 192
Southern Right Whale Pulsive Call[24]Clark, C. W. (1983). Acoustic Communication and Behavior of the Southern Right Whale (Eubalaena Australis). In Communication and behavior of whales (Vol. No. 76, pp. 101–110). American Association for the Advancement of Science.[25]Clark, C. W. (1982). The acoustic repertoire of the Southern right whale, a quantitative analysis. Animal Behaviour, 30(4), 1060–1071. https://doi.org/10.1016/S0003-3472(82)80196-6[26]Cummings, W. C., Fish, J. F., & Thompson, P. O. (1972). Sound Production and Other Behavior of Southern Right Whales, Eubalen Glacialis. San Diego Society of Natural History. 172 – 187

 

Anthropogenic Sounds
Sounds generated by human activities are an important part of the total ocean acoustic background. Undersea sound is used for many valuable purposes, including communication, navigation, defense, research and exploration and fishing. However, some sounds are just a by-product of another activity, such as the noise generated by ships and by offshore industrial activities, including oil drilling and production.

Sounds generated by human activities cover a wide range of frequencies, from a few Hz up to several hundred kHz, and a wide range of source levels.

The source levels for some sounds generated by human activities are given in the following table.

Ships Underway[27]Richardson, W. J., Green, C. R., Malme, C. I. J., & Thomson, D. H. (1995). Marine Mammals and Noise. San Diego: Academic Press. Broadband Source Level
(underwater dB at 1 m)
Tug and Barge (18 km/hour) 171
Supply Ship (Kigoriak) 181
Large Tanker 186
Icebreaking 193

 

Military Sonars Broadband Source Level
(underwater dB at 1 m)
AN/SQS-53C
(U. S. Navy tactical mid-frequency sonar, center frequencies 2.6 and 3.3 kHz)[28]NOAA/NMFS and U. S. Navy. (2001). Joint Interim Report Bahamas Marine Mammal Stranding Event of 15-16 March 2000. https://repository.library.noaa.gov/view/noaa/16198
235
AN/SQS-56
(U. S. Navy tactical mid-frequency sonar, center frequencies 6.8 to 8.2 kHz)[29]NOAA/NMFS and U. S. Navy. (2001). Joint Interim Report Bahamas Marine Mammal Stranding Event of 15-16 March 2000. https://repository.library.noaa.gov/view/noaa/16198
223
SURTASS-LFA (100-500 Hz) [30]U. S. Navy. (2001). Final Overseas Environmental Impact Statement and Environmental Impact Statement for Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) Sonar. https://www.nepa.navy.mil/Portals/20/Documents/surtass-lfa/2018/02/FEIS-Vol-I.pdf 215 underwater dB for a single projector, with up to 18 projectors operating simultaneously in a vertical array

 

Ocean Acoustic Studies Broadband Source Level
(underwater dB at 1 m)
Heard Island Feasibility Test (HIFT)
(Center frequency 57 Hz)[31]Munk, W. H., Spindel, R. C., Baggeroer, A., & Birdsall, T. G. (1994). The Heard Island feasibility test. The Journal of the Acoustical Society of America, 96(4), 2330–2342. https://doi.org/10.1121/1.410105
206 underwater dB for a single projector, with up to 5 projectors operating simultaneously in a vertical array
Acoustic Thermometry of Ocean Climate (ATOC)/North Pacific Acoustic Laboratory (NPAL) (Center frequency 75 Hz)[32]Richardson, W. J., Green, C. R., Malme, C. I. J., & Thomson, D. H. (1995). Marine Mammals and Noise. San Diego: Academic Press. 195

 

Additional Links on DOSITS

References

  • Andrew, R. K., Howe, B. M., Mercer, J. A., & Dzieciuch, M. A. (2002). Ocean ambient sound: Comparing the 1960s with the 1990s for a receiver off the California coast. Acoustics Research Letters Online, 3(2), 65–70. https://doi.org/10.1121/1.1461915
  • Hatch, L. T., & Wright, A. J. (2007). A Brief Review of Anthropogenic Sound in the Oceans. International Journal of Comparative Psychology, 20, 121–133.
  • National Research Council (U.S.) (Ed.). (2003). Ocean noise and marine mammals. Washington, D.C: National Academies Press.
  • Wenz, G. M. (1962). Acoustic ambient noise in the ocean: Spectra and sources. The Journal of the Acoustical Society of America, 34(12), 1936–1956. https://doi.org/10.1121/1.1909155

Cited References

Cited References
1 Møhl, B., Wahlberg, M., Madsen, P. T., Miller, L. A., & Surlykke, A. (2000). Sperm whale clicks: Directionality and source level revisited. The Journal of the Acoustical Society of America, 107(1), 638–648. https://doi.org/10.1121/1.428329
2 Watkins, W. A. (1980). Acoustics and the Behavior of Sperm Whales. In R.-G. Busnel & J. F. Fish (Eds.), Animal Sonar Systems (pp. 283–290). Boston, MA: Springer US. https://doi.org/10.1007/978-1-4684-7254-7_11
3 Levenson, C. (1974). Source level and bistatic target strength of the sperm whale ( Physeter catodon ) measured from an oceanographic aircraft. The Journal of the Acoustical Society of America, 55(5), 1100–1103. https://doi.org/10.1121/1.1914660
4 Watkins, W. A., & Schevill, W. E. (1977). Sperm whale codas. The Journal of the Acoustical Society of America, 62(6), 1485. https://doi.org/10.1121/1.381678
5 Norris, S. (1994). The Hawaiian Spinner Dolphin. Univ of California Press.
6, 27, 32 Richardson, W. J., Green, C. R., Malme, C. I. J., & Thomson, D. H. (1995). Marine Mammals and Noise. San Diego: Academic Press.
7 Cummings, W. C., & Thompson, P. O. (1994). Characteristics and seasons of blue and finback whale sounds along the U.S. west coast as recorded at SOSUS stations. The Journal of the Acoustical Society of America, 95(5), 2853–2853. https://doi.org/10.1121/1.409514
8 Watkins, W. A., Tyack, P., Moore, K. E., & Bird, J. E. (1987). The 20‐Hz signals of finback whales ( Balaenoptera physalus ). The Journal of the Acoustical Society of America, 82(6), 1901–1912. https://doi.org/10.1121/1.395685
9 Edds, P. L. (1988). Characteristics of finback balaenoptera physalus vocalizations in the St. Lawrence estuary. Bioacoustics, 1(2–3), 131–149. https://doi.org/10.1080/09524622.1988.9753087
10 Watkins, W. A. (1981). Activities and underwater sounds of fin whales (Balaenoptera Physalus). Scientific Reports of the Whales Research Institute (Japan), 83–117.
11 Stafford, K. M., Fox, C. G., & Mate, B. R. (1994). Acoustic detection and location of blue whales ( Balaenoptera musculus) from SOSUS data by matched filtering. The Journal of the Acoustical Society of America, 96(5), 3250–3251. https://doi.org/10.1121/1.411056
12 Edds-Walton, P. L. (1997). Acoustic communication signals of mysticete whales. Bioacoustics, 8(1–2), 47–60. https://doi.org/10.1080/09524622.1997.9753353
13 Aroyan, J. L., McDonald, M. A., Webb, S. C., Hildebrand, J. A., Clark, D., Laitman, J. T., & Reidenberg, J. S. (2000). Acoustic Models of Sound Production and Propagation. In W. W. L. Au, R. R. Fay, & A. N. Popper (Eds.), Hearing by Whales and Dolphins (pp. 409–469). New York, NY: Springer New York. https://doi.org/10.1007/978-1-4612-1150-1_10
14 Swartz, S. L., & Cummings, W. C. (1978). Gray whales, Eschrichtius robustus in Laguna San Ignacio, Baja California, Mexico Prepared by San Diego Natural History Museum for U.S. Marine Mammal Commission, Washington, D.C.
15 Fish, J. F., Sumich, J. L., & Lingle, G. L. (1974). Sounds Produced by the Gray Whale, Eschrichtius Robustus. Marine Fisheries Review, 36(4), 38–45.
16 Cummings, W. C., Thompson, P. O., & Cook, R. (1968). Underwater sounds of migrating gray whales, Eschrichtius glaucus (Cope). The Journal of the Acoustical Society of America, 44(5), 1278–1281. https://doi.org/10.1121/1.1911259
17 Ljungblad, D. K., Thompson, P. O., & Moore, S. E. (1982). Underwater sounds recorded from migrating bowhead whales, Balaena mysticetus, in 1979. The Journal of the Acoustical Society of America, 71(2), 477–482. https://doi.org/10.1121/1.387419
18 Cummings, W. C., & Holliday, D. V. (1987). Sounds and source levels from bowhead whales off Pt. Barrow, Alaska. The Journal of the Acoustical Society of America, 82(3), 814–821. https://doi.org/10.1121/1.395279
19 Wursig, B. and C. W. Clark. (1993). Behavior. in J. J. Burns, J. J. Montague, and C. J. Cowles, editors. The Bowhead Whale. Society of Marine Mammalogy.
20 Frankle, A. S. (1994). Acoustic and Visual Tracking Reveals Distribution, Song Variability and Social Roles of Humpback Whales in Hawaiian waters.(Megaptera Novaeangliae) (p. 142). Manoa HI: University of Hawaii.
21 Payne, K., & Payne, R. (2010). Large scale changes over 19 years in songs of humpback whales in Bermuda. Zeitschrift Für Tierpsychologie, 68(2), 89–114. https://doi.org/10.1111/j.1439-0310.1985.tb00118.x
22 Thompson, T. J., Winn, H. E., & Perkins, P. J. (1979). Mysticete Sounds. In H. E. Winn & B. L. Olla (Eds.), Behavior of Marine Animals: Current Perspectives in Research (pp. 403–431). Boston, MA: Springer US. https://doi.org/10.1007/978-1-4684-2985-5_12
23 Thompson, P. O., Cummings, W. C., & Ha, S. J. (1986). Sounds, source levels, and associated behavior of humpback whales, Southeast Alaska. The Journal of the Acoustical Society of America, 80(3), 735–740. https://doi.org/10.1121/1.393947
24 Clark, C. W. (1983). Acoustic Communication and Behavior of the Southern Right Whale (Eubalaena Australis). In Communication and behavior of whales (Vol. No. 76, pp. 101–110). American Association for the Advancement of Science.
25 Clark, C. W. (1982). The acoustic repertoire of the Southern right whale, a quantitative analysis. Animal Behaviour, 30(4), 1060–1071. https://doi.org/10.1016/S0003-3472(82)80196-6
26 Cummings, W. C., Fish, J. F., & Thompson, P. O. (1972). Sound Production and Other Behavior of Southern Right Whales, Eubalen Glacialis. San Diego Society of Natural History.
28, 29 NOAA/NMFS and U. S. Navy. (2001). Joint Interim Report Bahamas Marine Mammal Stranding Event of 15-16 March 2000. https://repository.library.noaa.gov/view/noaa/16198
30 U. S. Navy. (2001). Final Overseas Environmental Impact Statement and Environmental Impact Statement for Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) Sonar. https://www.nepa.navy.mil/Portals/20/Documents/surtass-lfa/2018/02/FEIS-Vol-I.pdf
31 Munk, W. H., Spindel, R. C., Baggeroer, A., & Birdsall, T. G. (1994). The Heard Island feasibility test. The Journal of the Acoustical Society of America, 96(4), 2330–2342. https://doi.org/10.1121/1.410105