Editing Dolphin (section)

===Vocalization===
[[File:Dolphin1.jpg|thumb|upright=1.35|[[Spectrogram]] of dolphin vocalizations. Whistles, whines, and clicks are visible as upside down V's, horizontal striations, and vertical lines, respectively.]]

Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: [[frequency modulated]] whistles, burst-pulsed sounds, and clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function,<ref>{{cite web |last = Viegas |first = Jennifer |title = Dolphins Talk Like Humans |work = Discovery News |year = 2011 |url = http://news.discovery.com/animals/dolphin-talk-communication-humans-110906.html |access-date = September 19, 2011 |archive-date = September 24, 2011 |archive-url = https://web.archive.org/web/20110924060555/http://news.discovery.com/animals/dolphin-talk-communication-humans-110906.html |url-status = dead }}</ref> and through burst-pulsed sounds, though the nature and extent of that ability is not known. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the [[Whale sound|loudest sounds made by marine animals]].<ref name="Au2012">{{cite book|last=Au|first=Whitlow W.L.|title=The Sonar of Dolphins|url={{google books |plainurl=y |id=NEXTBwAAQBAJ}}|date=December 6, 2012|publisher=Springer Science & Business Media|isbn=978-1-4612-4356-4}}</ref>

Bottlenose dolphins have been found to have signature whistles, a whistle that is unique to a specific individual. These whistles are used in order for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans.<ref>{{cite news |url=https://www.bbc.co.uk/news/science-environment-23410137 |title=Dolphins 'call each other by name' |date=July 22, 2013 |work=BBC News}}</ref> These signature whistles are developed during a dolphin's first year; it continues to maintain the same sound throughout its lifetime.<ref>{{cite journal|last=Janik|first=Vincent|author2=Laela Sayigh|title=Communication in bottlenose dolphins: 50 years of signature whistle research|journal=Journal of Comparative Physiology|date=May 7, 2013|volume=199|issue=6|pages=479–489|doi=10.1007/s00359-013-0817-7|pmid=23649908|s2cid=15378374}}<!--|access-date=January 30, 2014--></ref> In order to obtain each individual whistle sound, dolphins undergo vocal production learning. This consists of an experience with other dolphins that modifies the signal structure of an existing whistle sound. An auditory experience influences the whistle development of each dolphin. Dolphins are able to communicate to one another by addressing another dolphin through mimicking their whistle. The signature whistle of a male bottlenose dolphin tends to be similar to that of his mother, while the signature whistle of a female bottlenose dolphin tends to be more distinguishing.<ref>{{cite web |url=http://www.whoi.edu/science/B/people/kamaral/marinemammalacoustics.html |title=Marine Mammal vocalizations: language or behavior? |date=August 24, 2013}}</ref> Bottlenose dolphins have a strong memory when it comes to these signature whistles, as they are able to relate to a signature whistle of an individual they have not encountered for over twenty years.<ref>{{cite web |url=http://news.uchicago.edu/article/2013/08/06/dolphins-keep-lifelong-social-memories-longest-non-human-species |title=Dolphins keep lifelong social memories, longest in a non-human species |date=August 24, 2013}}</ref> Research done on signature whistle usage by other dolphin species is relatively limited. The research on other species done so far has yielded varied outcomes and inconclusive results.<ref>Emily T. Griffiths (2009). "[http://www.seawatchfoundation.org.uk/wp-content/uploads/2012/08/Griffiths2009_SBCDwhistle-repertoire.pdf Whistle repertoire analysis of the short beaked Common Dolphin, ''Delphinus delphis'', from the Celtic Deep and the Eastern Tropical Pacific Ocean]", Master's Thesis, School of Ocean Sciences
Bangor University</ref><ref>Melba C. Caldwell et al. – ''Statistical Evidence for Signature Whistles in the Spotted Dolphin, ''Stenella plagiodon''.''</ref><ref>Melba C. Caldwell et al. – ''Statistical Evidence for Signature Whistles in the Pacific Whitesided Dolphin, ''Lagenorhynchus obliquidens''.''</ref><ref>Rüdiger Riesch et al. – ''Stability and group specificity of stereotyped whistles in resident killer whales, Orcinus orca, off British Columbia.''</ref>

Because dolphins are generally associated in groups, communication is necessary. Signal masking is when other similar sounds (conspecific sounds) interfere with the original acoustic sound.<ref>{{cite journal|last=Quick|first=Nicola|author2=Vincent Janik|title=Whistle Rates of Wild Bottlenose Dolphins (''Tursiops truncatus''): Influences of Group Size and Behavior|journal=Journal of Comparative Psychology|year=2008|volume=122|issue=3|pages=305–311|doi=10.1037/0735-7036.122.3.305|pmid=18729659}}<!--|access-date=January 27, 2014--></ref> In larger groups, individual whistle sounds are less prominent. Dolphins tend to travel in pods, upon which there are groups of dolphins that range from a few to many. Although they are traveling in these pods, the dolphins do not necessarily swim right next to each other. Rather, they swim within the same general vicinity. In order to prevent losing one of their pod members, there are higher whistle rates. Because their group members were spread out, this was done in order to continue traveling together.