Did You Know: A Rotary Subwoofer can Reproduce a Tiger's 18 Hz Roar

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It is a commonly held belief that the frequency response of human hearing is between 20 Hz and 20,000 Hz, with degeneration of the upper frequencies occurring as a person grows older. More recent research may indicate that human beings can detect signals much higher than this, though the perception of those frequencies may be expressed as harmonic interactions and by the transient crossings in the time domain. But what about experiencing sounds below 20 Hz?

"New technologies such as the remarkable rotary subwoofer now make this possible..."

Generally, it’s understood that human beings can’t detect sounds below 20 Hz, which is why the stated frequency response of many products is from 20 to 20,000 Hz. Part of this impression comes from the challenges in using traditional cone and voice coil subwoofers to produce these frequencies at sufficiently high levels. New technologies such as the remarkable rotary subwoofer now make this possible, and human beings can, in fact, feel and be affected by these infrasonic frequencies.

In nature, infrasound is common. Elephants can trumpet to one another, and whales can communicate at great distances by generating these tones. One infrasonic frequency of particular interest is centered around 18 Hz and is generated by the unusual shape, stretch, and shear-ability in the folds of a Siberian tiger’s vocal chords.   

Based on studies by bio-acoustic specialist Dr. Elizabeth Von Muggenthaler, of the Fauna Communication Research Institute, and Edward J Walsh of the Boys Town National Research Hospital, tigers have been observed to emit growls and roars for a variety of reasons such as: marking territory, attracting mates, and scaring off rivals. They can generate sounds as loud as 114 dB in the audible spectrum, but the tone at 18 Hz is interesting because the combination of the infrasonic tone with the roar within the higher spectrum may cause momentary paralysis to animals within earshot. 

As if it weren’t enough that tigers can jump more than 30 feet, they may also be equipped with this infrasonic stun gun.      

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