December 2018 Newsletter: Long Distance Communication? Use Your Head!

The holiday season is rapidly approaching.  Wouldn’t it be helpful if you could read your friend’s and family’s minds from a long distance to figure out what gifts to buy?  Elephants can do just that…sort of. Read on to learn more about these head-centered lines of communication.

Very low-frequency sounds, which are below the lower threshold of human hearing of 20 Hz, are known as “infrasonic sounds”.  Using infrasonic sounds, elephants are able to command a somewhat private communication channel over long distances, since most other animals are unable to process sound waves below 20 Hz; they may sense or feel the energy, but not necessarily be able to discern the nature of the source.  This private line plays an important role in the herd’s complex social life.

What about the mind reading part?  It’s not exactly mind reading, but it is believed that elephants’ low-frequency communication, generally occurring between a frequency range of 14 to 24 Hz, originates from a flutter spot on the giant animals’ foreheads.  This phenomenon was first discovered when elephant researchers consistently felt “unusual throbbing sensations” in the air around them that lasted 10 to 15 seconds.  This led the researchers to use ultra-sensitive acoustic mapping equipment to investigate.  They found that there was a spot on the elephants’ foreheads that trembled when the animals uttered audible vocal calls, such as rumbles or purring sounds.

Most people associate elephant communication with their trumpeting trunks.  Elephants do in fact utilize their trunks to communicate, but for different purposes.  Baby elephants, for example, are drastically smaller than adults and, as a result, do not have the same ability to generate and interpret infrasonic sounds.  The same way a subwoofer with a larger speaker is required to generate bass frequencies on your home audio system, elephants need a large diaphram (an adults forehead, for example) to send and receive low-frequency content efficiently.  The lower the frequency, the larger the wavelength, and the more energy required to move a larger amount of air.  Elephants use their trunks and vocal chords to make sounds at higher frequencies (to communicate with their children or to warn a lion to back off) and employ the more private infrasonic channel to communicate with other adults.

The other benefit of infrasonic communication is that low frequencies are more omni-directional.  If an elephant wishes to communicate with other groups or is trying to find a mate who may be many miles away, the infrasonic content is emitted in all directions and can travel great distances.  When more directional, localized communication is required – cue the trunk!

While elephants cannot actually read minds, they are great communicators who use their heads to do so.  Use your head and don’t forget to employ your own long-distance communication method to send well wishes to your family and friends this season. And from everyone at Metropolitan Acoustics, Happy Holidays!

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