Whale Chat
Aquatic Animals and Underwater Sound
The clearest tropical waters rarely have visibility greater than 75m, whereas moderately loud sounds can transmit for tens or even hundreds of kilometers underwater. For this reason, many aquatic animals have sensitive hearing, and some communicate with sound as well. Killer whales use sound to navigate, to avoid obstacles, to locate prey and to communicate. Because killer whales can often be heard at greater distances than they can be seen, whale researchers often use hydrophones (underwater microphones) to find them.
The Sounds of Killer Whales
Killer whales produce three kinds of sounds.
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Clicks
Clicks are usually produced in rapid series and are similar to sounds you'd make running you fingernails across a comb. Clicks are used primarly for echolocation - more below. |
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Whistles
Killer whale whistles are used for communication and sound a lot like human whistles. They are continuous sounds and are referred to as 'pure tones'. Their function isn't entirely known, but they seem to play a role in communicating the emotional state and location of individuals - as they do in humans! |
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Calls
Referred to technically as 'burst pulse calls' - killer whale calls are very rapid streams of sound pulses that sound continuous to our ears. Most sound somewhat like human cries or screams, some sound a bit like a squeaky door or creaking floorboard. Many of the calls used by killer whales are 'stereotyped' or produced repeatedly by a given group of killer whales. Resident killer whales even use sound as a kind of family badge and researchers have discovered a lot about their family relationships by simply listening to the sound of their calls. Young killer whales learn their calls from their mother and other members of their family. |
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"Reading" Sound with Spectrograms
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Just as musicians have a well-developed system for writing and reading music, researchers analyzing biological sounds - including voices - have developed spectrograms as a way to display sounds. Like a musical score, spectrograms are written from left to right and represent frequency by height - higher frequency sounds appear above lower frequency sounds. Unlike a muscial score however, the volume or loudness of a sound is indicated by the intensity of the spectrogram... quite sounds are lightly shaded, loud sounds are dark, moderate sounds are in between. Because most biological sounds are complex and do not consist of notes or chords, spectrograms tend to look more like a section of fingerprint than a musical score - and hence, they are sometimes referred to as voiceprints. The spectrogram of any particular stereotyped call is easily distinguished from all other stereotyped calls on a spectrogram.
Below are the spectrograms associated with five different calls. |
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n4 n7 n8
 
n9 n13
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Echolocation
Whale Dialects
In the 1980’s, Canadian researcher (and Killer Whale Adoption Program founder) Dr John Ford discovered that each pod of resident killer whales uses a unique DIALECT, or set of stereotyped calls. Although common in birds, the only other mammals known to have true dialects are humans and a few other whales. Ford also discovered that the calls of Biggs (transient) killer whales are quite distinct from those used by residents, and that all Biggs (transients) in BC have a common dialect.
Listen to the differences in sound use by residents, Biggs (transients) and offshores.