Editing Blue whale (section)

===Vocalizations===
{{listen
 | pos          = right
 | filename     = Blue whale atlantic1.ogg
 | title        = A blue whale song
 | description  = Recorded in the Atlantic (1)
 | format       = [[Ogg]]
 | filename2    = Blue whale atlantic3.ogg
 | title2       = A blue whale song
 | description2 = Recorded in the Atlantic (2)
 | format2      = [[Ogg]]
 | filename3    = Blue_Whale_NE_Pacific.ogg
 | title3       = A blue whale song
 | description3 = Recorded in North Eastern Pacific
 | format3      = [[Ogg]]
 | filename4    = Blue_Whale_South_Pacific.ogg
 | title4       = A blue whale song
 | description4 = Recorded in the South Pacific
 | format4      = [[Ogg]]
 | filename5    = Blue_Whale_West_Pacific.ogg
 | title5       = A blue whale song
 | description5 = Recorded in the West Pacific
 | format5      = [[Ogg]]
}}
Blue whales produce some of the loudest and lowest [[frequency]] vocalizations in the animal kingdom,<ref name=NOAA/> and their inner ears appear well adapted for detecting [[Low frequency|low-frequency]] sounds.<ref name=Yamato_etal_2008>{{cite journal | author1=Yamato, M. | author2=Ketten, D. R. | author3=Arruda, J. | author4=Cramer, S. | title=Biomechanical and structural modeling of hearing in baleen whales | journal=Bioacoustics | volume=17 | issue=1–3 | pages=100–102 | date=2008| doi=10.1080/09524622.2008.9753781 | bibcode=2008Bioac..17..100Y | s2cid=85314872 }}</ref> The [[fundamental frequency]] for blue whale [[Animal communication#Auditory|vocalizations]] ranges from 8 to 25&nbsp;Hz.<ref name=Stafford_etal_1998>{{cite journal | author1=Stafford, K. M. | author2=Fox, G. C. | author3=Clark, D. S. | title=Long-range acoustic detection and localization of blue whale calls in the northeast Pacific Ocean | journal=Journal of the Acoustical Society of America | volume=50 | issue=4 | pages=1193–1198 | date=1998| bibcode=1998ASAJ..104.3616S | doi=10.1121/1.423944 | pmid=9857519 }}</ref> Blue whale songs vary between populations.<ref name=McDonald_etal_2006>{{cite journal | author1=McDonald, M. A. | author2=Mesnick, S. L. | author3=Hildebrand, J. A. | title=Biogeographic characterization of blue whale song worldwide: Using song to identify populations | journal=Journal of Cetacean Research and Management | volume=8 | pages=55–66 | date=2023| doi=10.47536/jcrm.v8i1.702 | s2cid=18769917 | doi-access=free }}</ref>

Vocalizations produced by the Eastern North Pacific population have been well studied. This population produces pulsed calls ("A") and tonal calls ("B"), upswept tones that precede type B calls ("C") and separate downswept tones ("D").<ref name=Aroyan_etal_2000>{{cite book | author1=Aroyan, J. L. | author2=McDonald, M. A. | author3=Webb, S. C. | author4=Hildebrand, J. A. | author5=Clark, D. S. | author6=Laitman, J. T. | author7=Reidenberg, J. S. | title=Hearing by whales and dolphins | chapter=Acoustic models of sound production and propagation | editor1-last=Au | editor1-first=W. W. A. | editor2-last=Popper | editor2-first=A. | editor3-last=Fay | editor3-first=R. N. | publisher=Springer-Verlag | location=New York | page=442 | date=2000}}</ref><ref name=McDonald_etal_2001>{{cite journal | author1=McDonald, M. A. | author2=Calambokidis, J. | author3=Teranishi, A. M. | author4=Hildebrand, J. A. | title=The acoustic calls of blue whales off California with gender data | journal=Journal of the Acoustical Society of America | volume=109 | issue=4 | pages=1728–1735 | date=2001| doi=10.1121/1.1353593 | pmid=11325141 | bibcode=2001ASAJ..109.1728M | url=http://www.escholarship.org/uc/item/6vg9t2g7 }}</ref> A and B calls are often produced in repeated co-occurring sequences and sung only by males, suggesting a reproductive function.<ref name=McDonald_etal_2001/><ref name=Oleson_etal_2007a>{{cite journal | author1=Oleson, E. M. | author2=Calambokidis, J. | author3=Burgess, W. C. | author4=McDonald, M. A. | author5=LeDuc, C. A. | author6=Hildebrand, J. A. | title=Behavioral context of call production by eastern North Pacific blue whales | journal= [[Marine Ecology Progress Series]]| volume=330 | pages=269–284 | date=2007| doi=10.3354/meps330269 | bibcode=2007MEPS..330..269O | doi-access=free }}</ref> D calls may have multiple functions. They are produced by both sexes during social interactions while feeding.<ref name=Oleson_etal_2007a/><ref name=Lewis_etal_2018>{{cite journal | author1=Lewis, L. A. | author2=Calambokidis, J. | author3=Stimpert, A. K. | author4=Fahlbusch, J. | author5=Friedlaender, A. S. | author6=McKenna, M. F. | author7=Mesnick, S. | author8=Oleson, E. M. | author9=Southall, B. L. | author10=Szesciorka, A. S. | author11=Sirovic, A. | title=Context-dependent variability in blue whale acoustic behaviour | journal=[[Royal Society Open Science]] | volume=5 | issue=8 | page=1080241 | date=2018 | doi=10.1098/rsos.180241| pmid=30225013 | pmc=6124089 }}</ref> and by males when competing for mates.<ref name=Schall_etal_2019/>

Blue whale calls recorded off Sri Lanka have a three-unit phrase. The first unit is a 19.8 to 43.5&nbsp;Hz pulsive call, and is normally 17.9 ± 5.2 seconds long. The second unit is a 55.9 to 72.4&nbsp;Hz [[Frequency modulation|FM]] upsweep that is 13.8 ± 1.1 seconds long. The final unit is 28.5 ± 1.6 seconds long with a tone of 108 to 104.7&nbsp;Hz.<ref name=Stafford_etal_2010>{{cite journal | author1=Stafford, K. M. | author2=Chapp, E. | author3=Bohnenstiel, D. | author4=Tolstoy, M. | author4-link=Maya Tolstoy | title=Seasonal detection of three types of "pygmy" blue whale calls in the Indian Ocean | journal=Marine Mammal Science | volume=27 | issue=4 | pages=828–840 | date=2010| doi=10.1111/j.1748-7692.2010.00437.x }}</ref> A blue whale call recorded off Madagascar, a two-unit phrase,<ref name=Ljungblad_etal_1998>{{cite report | author1=Ljungblad, D. K. | author2=Clark, C. W. | author3=Shimada, H. | title=A comparison of sounds attributed to pygmy blue whales (''Balaenoptera musculus brevicauda'') recorded south of the Madagascar Plateau and those attributed to 'true' blue whales (''Balaenoptera musculus'') recorded off Antarctica | publisher=International Whaling Commission | volume=48 | pages=439–442 | date=1998}}</ref> consists of 5–7 pulses with a [[center frequency]] of 35.1 ± 0.7&nbsp;Hz lasting 4.4 ± 0.5 seconds proceeding a 35 ± 0&nbsp;Hz tone that is 10.9 ± 1.1 seconds long.<ref name=Stafford_etal_2010/> In the Southern Ocean, blue whales produce 18-second vocals which start with a 9-second-long, 27&nbsp;Hz tone, and then a 1-second downsweep to 19&nbsp;Hz, followed by a downsweep further to 18&nbsp;Hz.<ref name=Sirovic_etal_2004>{{cite journal | author1=Sirovic, A. | author2=Hildebrand, J. A. | author3=Wiggins, S. M. | author4=McDonald, M. A. | author5=Moore, S. E. | author6=Thiele, D. | title=Seasonality of blue and fin whale calls and the influence of sea ice in the Western Antarctic Peninsula | journal=[[Deep Sea Research Part II: Topical Studies in Oceanography]] | volume=51 | issue=17–19 | pages=2327–2344 | date=2004| doi=10.1016/j.dsr2.2004.08.005 | bibcode=2004DSRII..51.2327S }}</ref><ref name=Rankin_etal_2005/> Other vocalizations include 1–4 second long, frequency-modulated calls with a frequency of 80 and 38&nbsp;Hz.<ref name=Rankin_etal_2005>{{cite journal | author1=Rankin, S. | author2=Ljungblad, D. | author3=Clark, C. | author4=Kato, H. | title=Vocalisations of Antarctic blue whales, ''Balaenoptera musculus intermedia'', recorded during the 2001/2002 and 2002/2003 IWC/SOWER circumpolar cruises, Area V, Antarctica | journal=Journal of Cetacean Research and Management | volume=7 | pages=13–20 | date=2023| doi=10.47536/jcrm.v7i1.752 | s2cid=43993242 | doi-access=free }}</ref><ref name=Sirovic_etal_2006>{{cite journal | author1=Sirovic, A. | author2=Hildebrand, J. A. | author3=Thiele, D. | title=Baleen whales in the Scotia Sea in January and February 2003 | journal=Journal of Cetacean Research and Management | volume=8 | pages=161–171 | date=2006| doi=10.47536/jcrm.v8i2.712 | s2cid=251277044 | doi-access=free }}</ref>

There is evidence that some blue whale songs have temporally declined in tonal frequency.<ref name=Nieukirk_etal_2005>{{cite conference | author1=Nieukirk, S. L. | author2=Mellinger, D. K. | author3=Hildebrand, J. A. | author4=McDonald, M. A. | author5=Dziak, R. P. | title=Downward shift in the frequency of blue whale vocalizations | conference=16th Biennial Conference on the Biology of Marine Mammals | location=San Diego, CA | page=205 | date=2005}}</ref><ref name=McDonald_etal_2009>{{cite journal | author1=McDonald, M. A. | author2=Hildebrand, J. A. | author3=Mesnick, S. | title=Worldwide decline in tonal frequencies of blue whale songs | journal=Endangered Species Research | volume=9 | pages=13–21 | date=2009| doi=10.3354/esr00217 | doi-access=free }}</ref><ref name=Leroy_etal_2018>{{cite journal | author1=Leroy, E. C. | author2=Royer, J.-Y. | author3=Bonnel, J. | author4=Samaran, F. | title=Long-term and seasonal changes of large whale call frequency in the southern Indian Ocean | journal=[[Journal of Geophysical Research: Oceans]] | volume=123 | issue=11 | pages=8568–8580 | date=2018| doi=10.1029/2018JC014352 | bibcode=2018JGRC..123.8568L | s2cid=135201588 | url=https://archimer.ifremer.fr/doc/00516/62730/ | doi-access=free | hdl=1912/10837 | hdl-access=free }}</ref> The vocalization of blue whales in the Eastern North Pacific decreased in tonal frequency by 31% from the early 1960s to the early 21st century.<ref name=Nieukirk_etal_2005/><ref name=McDonald_etal_2009/> The frequency of pygmy blue whales in the Antarctic has decreased by a few tenths of a hertz every year starting in 2002.<ref name=Leroy_etal_2018/> It is possible that as blue whale populations recover from whaling, there is increasing sexual selection pressure (i.e., a lower frequency indicates a larger body size).<ref name=McDonald_etal_2009/>