Editing Whale vocalization (section)

== Mechanisms of sound production ==
[[Humans]] produce [[voice (phonetics)|voiced]] sounds by passing air through the [[larynx]]. Within the larynx, when the [[vocal cords]] are brought close together, the passing air will force them to alternately close and open, separating the continuous airstream into discrete pulses of air that are heard as a vibration.<ref>{{cite web |url=http://www.dosits.org/animals/soundproduction/mammalsproduce/ |date=July 2009 |title=How do marine mammals produce sounds? |access-date=15 October 2013}}</ref> This vibration is further modified by [[speech organs]] in the [[mouth|oral]] and [[nasal cavity|nasal]] cavities, creating sounds which are used in [[human voice|human speech]].

Cetacean sound production differs markedly from this mechanism. The precise mechanism differs in the two suborders of cetaceans: the ''Odontoceti'' ([[toothed whales]], including dolphins) and the ''Mysticeti'' ([[baleen whale]]s, including the largest whales such as the [[blue whale]]).

===Odontocete whales ===
[[File:Delfinekko.gif|thumb|left|Process in a dolphin echolocation: in green the sounds generated by the dolphin, in red from the fish.]]
[[Image:Dolphin head.svg|300px|thumb|alt=Outline of what's inside a dolphin head. The skull is to the rear of the head, with the jaw bones extending narrowly forward to the nose. The anterior bursa occupies most of the upper front of the head, ahead of the skull and above the jaw. A network of air passages run from the upper roof of the mouth, past the back of the anterior bursa, to the [[blowhole (anatomy)|blowhole]]. The posterior bursa is a small region behind the air passages, opposite the anterior bursa. Small phonic tips connect the bursa regions to the air passages.|Idealized dolphin head showing the regions involved in sound production. This image was redrawn from Cranford (2000).]]
[[Odontocetes]] produce rapid bursts of high-frequency clicks that are thought to be primarily for [[animal echolocation|echolocation]]. Specialized organs in an odontocete produce collections of clicks and buzzes at frequencies from 0.2 to 150&nbsp;kHz to obtain sonic information about its environment. Lower frequencies are used for distance echolocation, due to the fact that shorter wavelengths do not travel as far as longer wavelengths underwater. Higher frequencies are more effective at shorter distances, and can reveal more detailed information about a target. Echoes from clicks convey not only the distance to the target, but also the size, shape, speed, and vector of its movement. Additionally, echolocation allows the odontocete to easily discern the difference between objects that are different in material composition, even if visually identical, by their different densities. Individuals also appear to be able to isolate their own echoes during pod feeding activity without interference from other pod members' echolocations.<ref name="dolphins.org">{{cite web|url=http://www.dolphins.org/marineed_acoustics.php|title=How Dolphins Produce Sounds|website=Dolphin Research Center}}</ref>

Whistles are used for communication. Four- to six-month-old calves develop unique sounds that they use most frequently throughout their lives. Such "signature whistles" are distinctive to the individual and may serve as a form of identification among other odontocetes.<ref name="dolphins.org"/> Though a large pod of dolphins will produce a wide range of different noises, very little is known about the meaning of the sound. Frankel quotes one researcher who says listening to a school of odontocetes is like listening to a group of children at a school playground.<ref name=Frankel>Frankel, Adam S. "Sound production", ''Encyclopedia of Marine Mammals'', 1998, pp. 1126–1137. {{ISBN|0-12-551340-2}}.</ref>

The multiple sounds odontocetes make are produced by passing air through a structure in the head called the '''phonic lips'''.<ref name=":0">{{Cite journal|last1=Cranford|first1=Ted W.|last2=Elsberry|first2=Wesley R.|last3=Bonn|first3=William G. Van|last4=Jeffress|first4=Jennifer A.|last5=Chaplin|first5=Monica S.|last6=Blackwood|first6=Diane J.|last7=Carder|first7=Donald A.|last8=Kamolnick|first8=Tricia|last9=Todd|first9=Mark A.|title=Observation and analysis of sonar signal generation in the bottlenose dolphin (Tursiops truncatus): Evidence for two sonar sources|journal=Journal of Experimental Marine Biology and Ecology|volume=407|issue=1|pages=81–96|doi=10.1016/j.jembe.2011.07.010|year=2011|doi-access=free|url=https://escholarship.org/content/qt85p8z1vz/qt85p8z1vz.pdf?t=qjjiq9}}</ref> Biologically the structure is [[Homology (biology)|homologous]] to an upper lip located in the nasal cavity, but mechanistically the phonic lips act similarly to human [[vocal cords|vocal "cords]]" (vocal folds), which in humans are located in the [[larynx]]. As the air passes through this narrow passage, the phonic lip membranes are sucked together, causing the surrounding tissue to vibrate. These vibrations can, as with the vibrations in the human larynx, be consciously controlled with great sensitivity.<ref name=":0" /> The vibrations pass through the tissue of the head to the [[melon (whale)|melon]], which shapes and directs the sound into a beam of sound useful in echolocation. Every toothed whale except the [[sperm whale]] has two sets of phonic lips and is thus capable of making two sounds independently.<ref>{{cite journal |last1=Fitch |first1=W. T. |last2=Neubauer |first2=J. |last3=Herzel |first3=H. |year=2002 |title=Calls out of chaos: the adaptive significance of nonlinear phenomena in mammalian vocal production |journal=Anim. Behav. |volume=63 |pages=407–418 |doi=10.1006/anbe.2001.1912 |issue=3|s2cid=16090497 }}</ref> Once the air has passed the phonic lips it enters the [[vestibular system|vestibular sac]]. From there, the air may be recycled back into the lower part of the nasal complex, ready to be used for sound creation again, or passed out through the blowhole.<ref>{{cite web |last1=Elemans |first1=C.P.H |last2=Jiang |first2=W. |last3=Jensen |first3=M.H |title=Evolutionary novelties underlie sound production in baleen whales |url=https://doi.org/10.1038/s41586-024-07080-1 |website=Nature |access-date=6 December 2024}}</ref>

The [[French language|French]] name for phonic lips, ''museau de singe'', translates literally as "monkey's muzzle", which the phonic lip structure is supposed to resemble in sperm whales.<ref>{{cite web |url=http://www.spermwhale.org/SpermWhale/spermwhaleorgV1.html |title=Selected Whale Sciences Images - Volume 1 |author=Ted W. Cranford |access-date=20 October 2010}}</ref> New cranial analysis using [[computed axial tomography|computed axial]] and [[single photon emission computed tomography]] scans in 2004 showed, at least in the case of [[bottlenose dolphin]]s, that air might be supplied to the nasal complex from the lungs, enabling the sound creation process to continue for as long as the dolphin can add air from the lungs.<ref>{{cite journal |author1=Houser, Dorian S. |author2=Finneran, James |author3=Carder, Don |author4=Van Bonn, William |author5=Smith, Cynthia |author6=Hoh, Carl |author7=Mattrey, Robert |author8=Ridgway, Sam |year=2004 |title=Structural and functional imaging of bottlenose dolphin (''Tursiops truncatus'') cranial anatomy |journal=Journal of Experimental Biology |volume=207 |pages=3657–3665 |doi=10.1242/jeb.01207 |pmid=15371474 |issue=Pt 21|doi-access=free }}</ref>

====Sperm whale====
{{further|Sperm whale#Vocalization complex}}
The sperm whale's vocalizations are all based on clicking, described in four types: the usual echolocation, creaks, codas, and slow clicks.<ref name="Whitehead book">{{cite book |title=Sperm Whales: Social Evolution in the Ocean |author=Whitehead, H. |year=2003 |isbn=978-0-226-89518-5 |publisher=University of Chicago Press |location=Chicago |pages=135–141}}</ref> The most distinctive vocalizations are codas, which are short rhythmic sequences of clicks, mostly numbering 3–12 clicks, in stereotyped patterns.<ref name="Whitehead-2024">{{cite journal |author1=Hal Whitehead |title=Sperm whale clans and human societies |journal=[[Royal Society Open Science]] |date=2024 |volume=11 |issue=1 |doi=10.1098/rsos.231353|bibcode=2024RSOS...1131353W |pmc=10776220 }}</ref><ref name="Whitehead book"/> They are the result of [[vocal learning]] within a stable social group.<ref name="Gero-2016">{{cite journal |last1=Gero |first1=Shane |last2=Whitehead |first2=Hal |last3=Rendell |first3=Luke |title=Individual, unit and vocal clan level identity cues in sperm whale codas |journal=[[Royal Society Open Science]] |date=2016 |volume=3 |issue=1 |doi=10.1098/rsos.150372|bibcode=2016RSOS....350372G |hdl=10023/8071 |hdl-access=free }}</ref> Some codas express clan identity, and denote different patterns of travel, foraging, and socializing or avoidance among clans.<ref name="Safina-2020-pp16–19">{{cite book |last1=Safina |first1=Carl |title=Becoming Wild: How Animal Cultures Raise Families, Create Beauty, and Achieve Peace |date=2020 |publisher=[[Henry Holt and Company]] |isbn=9781250173331 |pages=16–19}}</ref><ref>{{cite journal |last1=Cantor |first1=Maurício |last2=Whitehead |first2=Hal |title=How does social behavior differ among sperm whale clans? |journal=Marine Mammal Science |date=October 2015 |volume=31 |issue=4 |pages=1275–1290 |doi=10.1111/mms.12218 |bibcode=2015MMamS..31.1275C }}</ref> As “arbitrary traits that function as reliable indicators of cultural group membership,” clan identity codas act as symbolic markers that modulate interactions between individuals.<ref name="Hersh-2022">{{cite journal |author1=Taylor A. Hersh |title=Evidence from sperm whale clans of symbolic marking in non-human cultures |journal=[[PNAS]] |date=2022 |volume=119 |issue=37 |page=e2201692119 |doi=10.1073/pnas.2201692119 |publisher=[[National Academy of Sciences]] |doi-access=free |pmid=36074817 |pmc=9478646 |bibcode=2022PNAS..11901692H |display-authors=et al}}</ref>

Individual identity in sperm whale vocalizations is an ongoing scientific issue, however. A distinction needs to be made between cues and signals. Human acoustic tools can distinguish individual whales by analyzing micro-characteristics of their vocalizations, and the whales can probably do the same. This does not prove that the whales deliberately use some vocalizations to signal individual identity in the manner of the [[signature whistle]]s that bottlenose dolphins use as individual labels.<ref name="Gero-2016"/><ref name="Hersh-2022"/>

===Mysticete whales ===
[[Baleen whale|Mysticetes]] do not have phonic lip structure. Instead, they have a larynx that appears to play a role in sound production, as it has vocal folds (vocal "cord") homologs in the U-shaped fold supported by arytenoid cartilages.<ref name=":1" /> Whales do not have to exhale in order to produce sound, as they capture the air in a laryngeal sac. It is likely that they recycle air from this sac back to the lungs for the next vocalization.<ref name=":1">{{cite journal|last1=Reidenberg|first1=JS|last2=Laitman|first2=JT|title=Discovery of a low frequency sound source in Mysticeti (baleen whales): anatomical establishment of a vocal fold homolog.|journal=Anatomical Record|date=2007|volume=290|issue=6|pages=745–59|pmid=17516447 |doi=10.1002/ar.20544|s2cid=24620936|doi-access=free}}</ref> They do not have bony cranial sinuses, but there is a pterygoid air sac.  Its role in sound production is unclear (perhaps resonance?), but most likely it is for hearing, as it appears to preserve  an airspace at depth around the ear ossicles.<ref>{{Cite journal |last1=Reidenberg |first1=Joy S. |last2=Laitman |first2=Jeffrey T. |date=2008 |title=Sisters of the Sinuses: Cetacean Air Sacs |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.20792 |journal=The Anatomical Record |language=en |volume=291 |issue=11 |pages=1389–1396 |doi=10.1002/ar.20792 |pmid=18951477 |issn=1932-8486}}</ref>

==== Vocal plasticity and acoustic behavior====
There are at least nine separate blue whale acoustic populations worldwide.<ref>{{cite journal|vauthors=McDonald, MA, Messnick SL, Hildebrand JA|year=2023|title=Biogeographic characterisation of blue whale song worldwide: using song to identify populations|journal=Journal of Cetacean Research and Management|volume=8|pages=55–65|doi=10.47536/jcrm.v8i1.702 |s2cid=18769917 |url=http://www.cetus.ucsd.edu/docs/publications/McDonaldJCRM2006.pdf}}</ref> Over the last 50 years blue whales have changed the way they are singing. Calls are progressively getting lower in frequency.  For example, the Australian pygmy blue whales are decreasing their mean call frequency rate at approximately 0.35&nbsp;Hz/year.<ref>{{cite journal|title=Temporal segregation of the Australian and Antarctic blue whale call types (Balaenoptera musculus spp.)|first1=Joy S.|last1=Tripovich|first2=Holger|last2=Klinck|first3=Sharon L.|last3=Nieukirk|first4=Tempe|last4=Adams|first5=David K.|last5=Mellinger|first6=Naysa E.|last6=Balcazar|first7=Karolin|last7=Klinck|first8=Evelyn J. S.|last8=Hall|first9=Tracey L.|last9=Rogers|date=22 May 2015|journal=Journal of Mammalogy|volume=96|issue=3|pages=603–610|doi=10.1093/jmammal/gyv065|pmid=26937046|pmc=4668953}}</ref>

The migration patterns of blue whales remain unclear. Some populations appear to be resident in habitats of year-round high productivity in some years,<ref>{{cite journal | doi = 10.1093/jmammal/gyv065 | pmid=26937046 | volume=96 | issue=3 | title=Temporal segregation of the Australian and Antarctic blue whale call types (Balaenoptera musculusspp.) | journal=Journal of Mammalogy | pages=603–610| year=2015 | last1=Tripovich | first1=Joy S. | last2=Klinck | first2=Holger | last3=Nieukirk | first3=Sharon L. | last4=Adams | first4=Tempe | last5=Mellinger | first5=David K. | last6=Balcazar | first6=Naysa E. | last7=Klinck | first7=Karolin | last8=Hall | first8=Evelyn J. S. | last9=Rogers | first9=Tracey L. | pmc=4668953 }}</ref> while others undertake long migrations to high-latitude feeding grounds, but the extent of migrations and the components of the populations that undertake them are poorly known.<ref name = "IUCNblue">{{cite iucn|author= Cooke, J.G.|title= ''Balaenoptera musculus'' |errata=2019|page= e.T2477A156923585 |year= 2018|access-date= 27 January 2020}}</ref>

==== Sound levels ====
The frequency of baleen whale sounds ranges from 10 [[Hertz|Hz]] to 31&nbsp;kHz.<ref name=RGMT>{{cite book |title=Marine Mammals and Noise|author1=W. John Richardson|author2=Charles R. Greene Jr.|author3=Charles I. Malme|author4=Denis H. Thomson|year=1995|publisher=Academic Press|isbn=978-0-12-588440-2}}</ref> A list of typical levels is shown in the table below.

{| class="wikitable"
|-
! Source
! [[Broadband]] source level (dB re 1 <math>\mu</math>Pa at 1m)<ref name=KupermanRoux>{{cite book |author=Kuperman, Roux| editor=Rossing, Thomas D. |title=Springer Handbook of Acoustics |publisher=Springer |year=2007 | chapter = Underwater Acoustics |isbn=978-0-387-30446-5}}</ref>
|-
| [[Fin whale]] moans
| 155–186
|-
| [[Blue whale]] moans
| 155–188
|-
| [[Gray whale]] moans
| 142–185
|-
| [[Bowhead whale]] tonals, moans and song
| 128–189
|}