Perhaps our lack of inner peace is due to some extent to the effect
of noise upon the nervous system of modern people. Scientific
experiments show that noise in the place where we work, live, or
sleep reduces efficiency to a noticeable degree. Contrary to popular
belief, it is doubtful if we ever completely adjust our physical,
mental, or nervous mechanisms to noise. No matter how familiar a
repeated sound becomes, it never passes unheard by the subconscious.
Automobile horns, the roar of airplanes, and other strident noises
actually result in physical activity during sleep. Impulses
transmitted to and through the nerves by these sounds cause muscular
movements which detract from real rest. If the reaction is
sufficiently severe, it partakes of the nature of shock.
Norman Vincent Peale, "The Power of Positive Thinking" (1952)