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The humpback song, which is made up of repeated themes, can last for up to 30 minutes and some humpbacks sing for hours at a time! Only the males sing and all male humpbacks in the same region sing the same song. The song itself changes over time, making it different from year to year. The songs generally occur during the breeding season, suggesting that they are related to breeding. But researchers are still asking why do male humpbacks sing?
Whale Hearing
In addition to singing, humpbacks also hear well. Sound is exceptionally important
to marine mammals living in the ocean (a very noisy place). Hearing is a
well-developed sense in all cetaceans, largely because of the sensitive reception
of waterborne vibrations through bones in the head. Take a look at the size
of a whale's head compared to its entire skeleton. You will notice that the
head comprises up to one third of the total body length. The whale ear is
a tiny opening that closes underwater. The bone structure of the middle and
inner ears is modified from that of terrestrial (land-based) mammals to accommodate
hearing underwater.
Let's Dissect the Song
Humpback whales produce moans, grunts, blasts and shrieks. Each part of their
song is made up of sound waves. Some of these sound waves are high frequency.
If you could see these sounds, they would look like tall, pointed mountains.
Whales also emit low frequency sound waves. These waves are like hills that
are wide spread apart. These sound waves can travel very far in water without
losing energy. Researchers believe that some of these low frequency sounds
can travel more than 10,000 miles in some levels of the ocean!
Sound frequencies are measured in units called Hertz. The range of frequencies
that whales use are from 30 Hertz (Hz) to about 8,000 Hz, (8 kHZ). Humans can
only hear part of the whales' songs. We aren't able to hear the lowest of the
whale frequencies. Humans hear low frequency sounds starting at about 100 Hz.
Whale Songs Similar to Other Animals
Researchers have noted that whale songs sound very similar to the songs of
hoofed animals, such as. Elk (bugleing), cattle (mooing), and have more than
a passing resemblance to some of the elephant noises. One of the leading
researchers into humpback whale sounds, Katy Payne, also studies elephant
sounds and has found similarities between these two species.
Where are Sounds Produced?
The larynx was originally thought to be the site of sound production in cetaceans
but experiments on live, phonating dolphins showed that the larynx does not
move during vocalizations. Instead there are structures in the nasal system
including the nasal plug and the elaborate nasal sac system which move when
sound is produced, although the exact site of the sound generation is still
debated. You can read more about this fascinating subject in book called
BIOLOGY OF MARINE MAMMALS, by Reynolds and Rommel.
Try Listening for Yourself
Try This!
- Listen to the humpback songs. Can you tell which parts of the songs are the higher frequencies (short and high pitched) and which are the lower frequencies? How would you describe these songs in words? What do the songs remind you of? How are the three songs similar and how are they different?
- A whale's low frequency sounds can travel up to 10,000 miles. Take out your globe, and using the scale of miles on the key, explore how far this distance is. Imagine you are a whale; how far can you sing?
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