Sympathetic Vibrations

Mr. Ed Smith taught me physics at Withrow, and I recall him talking about the foot soldiers walking out of step over a bridge.  "Otherwise the vibrations can become so powerful the bridge will crumble."

The song of the soldiers whistling, "The Bridge over the River Kwai" comes to mind.  What a great movie.  And they built a masterful bridge, those World War Two  prisoners of war.

But we feel other songs from movies intensely, and our mind turns to certain themes.  The music stirs our emotions, and we know that music forewarns us of the scary part; we know the lovers are meeting at another type of music.  We feel like that tuning fork, that Mr. Smith told us about, that was not vibrating, and set on a sounding board, but when a vibrating one was set nearby, it began vibrating.



Under the heading, "Sympathetic Resonances" Wikipedia quotes Lewcock et al(2006):


The property of sympathetic vibration is encountered in its direct form in room acoustics in the rattling of window panes, light shades and movable panels in the presence of very loud sounds, such as may occasionally be produced by a full organ.  As these things rattle(or even if they do not audibly rattle) sound energy is being converted into mechanical energy, and so the sound is absorbed.  Wood paneling and anything else that is lightweight and relatively unrestrained have the same effect.  Absorptivity is at its highest at the resonance frequency, usually near or below 100Hz.




Interestingly you do not have to be hearing to hear the vibrations, and the room and furniture can send the beats to everyone through their sense of feeling, and even through the air.  We even dance to certain kinds of music which lack melody or lyrics, where the beats are dominant.

I recently watched "White Christmas" with Bing Crosby singing several Irving Berlin songs.  That composer was a genius, writing both the music and lyrics to many compositions throughout the movie.  We still hear the song every Christmas, and I believe almost everyone knows those words. I also love the song, "Count your Blessings", another beautiful song.  It moves my emotions, and the words themselves are powerful as a poem.

Watching my daughter perform with her Step Team, I feel the beats resound through the floor and the air.  The power of the steppers move us to tears and cheering within the first moments.  

Wikipedia explains:
          An example of proper sympathetic resonance is a windowpane rattling steadily at the very low powerful sound of a bus or truck engine going stationary.  The rattling will usually occur at a higher harmonic sound made by the engine.  As soon as the driver changes into gear the rattling will stop, often changing its rhythm before it stops altogether.  Powerful sopranos bursting wineglasses fits in to the same category- sympathetic resonance at a distance.-  Arden Wilken

But in the case of the human condition, we feel the resonance through our emotions and in our mind.  The power of music and beats can help the elderly and the sick. Known to all is the power of music and the beat of rhythms to which soldiers and performers dance.  It can strengthen the recovering, and encourage those hurt and in mourning.