The Power of Sound
by With few exceptions humans are a visually oriented species. Sound has been neglected in almost all communities. Yet sound has power from the power of infrasound to cause sickness or ultrasound to treat kidney stones or cancer through the power of music to change mood, to the power of orators to whip crowds into frenzy and the ability of poetry to reach beyond the conscious mind. Here a few aspects of the power of sound are discussed.
Physics
Sound is rhythmic compression waves in an elastic medium. It is created when a vibrating source disturbs the medium whether that be air, water or peanut butter. The vibrations carry energy so even at the level of physics sound has power.
Humans hear sound at frequencies between 20Hz ad 20,000Hz (A Hertz, the unit name commemorates a great scientist, is a wave frequency of one cyle per second, in motor terms 60rpm). Infrasound , frequencies to low to hear, has been credited with causing the heeling of alarm many experience in haunted houses, there are tales of high power infrasound generators that could bring down buildings or literally vibrate humans in the path of the sound to death.
In the Bible Joshua was allged to have brought the walls of Jericho down with the sound of trumpets: something that is just possible if the walls were unstable for any reason, though at this distance in time the truth of the tale or any explanation is impossible to establish. Caruso was alleged to have shattered a wine glass by singing a note at the resonant frequency of the glass, the frequency of the note emitted when the glass is tapped, though I find this hard to credit, experiments that tried to replicate this with commercial power sound generators failed to do so, though, high speed photography showed the glass distorted to an amazing degree. I recall talking to a Hi-Fi enthusiast who had converted the chimmeys in his house to Horn loudspeakers and aa low note played through these would ripple a listener’s clothes.
Ultrasound, sound too high in frequency to hear has been used to seal plastic bags and has a variety of therapeutic uses . Ultrasound, if focussed will heat up the area where it is focussed and the heating can be used for various things.
Everyday life
Thunder can terrify some people and even cause a heart attack ( as can any unexpected loud noise). Many ancient peoples associated thunder with a god The hiss of rain can depress or calm a listener, and the sound of male mosquito is used to repel the females, who are the ones that sting. A church organ can stir the listeners down to the bones, and I recall reading of a church organist died when the organ emitted an unusually large and unexpected noise in response to a key press. The vibrations cause by heavy traffic, sound transmitted through the ground, can crack walls and foundations and constant exposure to low frequency sound can be injurious to health, while there is some inconclusive evidence that animals can sense ultrasound that arises before earthquakes and ultrasonic dog whistles rely on the fact that dogs ( and cats) can hear sound at higher frequencies than humans.
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