Nazi Propoganda Director Joseph Goebbels, right, shakes hands with composer and Director of Music within the Propaganda Ministry, Richard Strauss. Photo from Draeske.org.
There is a movement going on today which asserts that most music made in the Western world resonates on a dissonant, unnatural level which could even have chronic mental and physically negative consequences. But before we get into all that, let’s begin with a brief history.
The predominant standard concert pitch of western music for roughly the last sixty years has been set at 440 Hz. This refers to a specific vibrational frequency that delivers a particular tone within an infinite set of frequencies, setting the standard for which all other tones in a given scale are based. In musicians’ terms, it is the note A above middle C. Think of it like reading magnetic North on a compass as opposed to the actual North Pole.
A musical pitch refers to the precise sound that emanates from an instrument or voice when hitting a particular note. Pitch may be explained either objectively as the name of a note, or the actual frequency of a particular tone; or subjectively, as in how the physical aspects of the sound are perceived by human ears.  Herein lies the controversy.
For most of history there were varying customary pitches employed depending on the musical style of the times, but a truly organized, accepted “gold standard” did not exist. In the mid-20th century this all changed. In 1939, Reich Master of Propaganda in Nazi Germany Joseph Goebbels was the first to push for the 440 Hz pitch to be standardized internationally– he succeeded in doing so only within Germany and, briefly, in England.
Prior to this, the American music industry had reached an informal standard of 440 Hz in 1926 for instrument manufacturing. In 1936, the American Standards Association recommended that the A above middle C be tuned to 440 Hz. This standard was taken up by the International Organization for Standardization in 1955. Although still not universally accepted, it has served since then as the audio frequency reference for the calibration of acoustic equipment and the tuning of pianos, violins, and other musical instruments. 
Prominent musician and manufacturer J.C. Deagan, who also campaigned for the 440 Hz standard, designed the 440 Hz-based war chimes that were used for World war II propaganda news reels. Interestingly, these same chimes are also used in the call signs for the NBC television network.
It should be noted that there exists an infinite number of frequencies out there — some see the standardization of 440 Hz as simply arbitrary, whereas others feel it’s downright sinister. Why attach so much animosity to a number? The answer lies in the work of two music-related scientific fields: Cymatics and psychoacoustics. Cymatics is the study of sound and vibration as they pertain to the physical plane. Experiments in cymatics have succeeded in actually making visible inherent geometries within sound and music. Sound amazing? It is. For a first-hand look, check out this video featuring an actual visualization of sound geometrics:
Meanwhile, psychoacoustics is the scientific study of sound perception. Specifically, it deals with the psychological and physiological responses associated with sound including speech and music.
Today, some people are championing the return to the 432 Hz standard, a frequency that carries the PHI ratio of Fibbonacci (famed mathematician of the Middle Ages) which is the golden mean in mathematics. The golden mean, a reoccurring “perfect” proportion found in nature and recreated through art, is found in everything from the distant solar systems and galaxies all the way to the molecular structure of our DNA. Thus a standard pitch which contains its proportions is thought to be better in keeping with nature. Indeed, some of the most striking and well-known music of the Western world has been based around the golden ratio, from the works of Mozart to the Blues.
440 Hz is believed by some to skew vibrations within the body due to its dissonant nature when compared to 432 Hz, a pitch which was adhered to in the sacred music of many cultures of antiquity. This number was also promulgated as the “frequency of the cosmos” by the Ancient Greek philosopher and mathematician Pythagoras.
In reference to cymatics, vibrations from frequencies of 432 Hz result in perfectly defined geometric shapes, whereas frequencies in 440 Hz do not. This leads some to believe that discordant frequencies that enter the human ear lead to discordance within the body.
In the world of psychoacoustics, recent studies have proven that ‘sound entrainment’ (synchronization of two differing systems) has been and still is used to coax brainwaves into certain patterns of thought and mood.  For many the fact that Nazi Germany leaders fought for the 440 Hz standard, and utilized it in their martial music, repudiates its power to put people into an aggressive and unbalanced state.
Though the 440 Hz standard has many opponents, in practice it is not as widely adhered to as many seem to believe. People, particularly artists (i.e. musicians) are flouting so-called standards all the time. Indeed, it seems that this supposed international standard, is often widely ignored — lower or higher tuning is common as one moves around the world or between genres of music. In fact, Led Zeppelin often tuned away from the 440 Hz standard to record much of their music in order to imbue their sound with a “different” and “unique” character.  Today, most music and listeners of the Western world are still vibrating to a supposedly dissonant chord. Here are two recordings identical except that one is tuned to 432 Hz and the other to 440 Hz (see the “Silent Night” renditions, halfway down this page).
Can you feel the difference?
- Levitin, Daniel J. This Is Your Brain On Music. London: Penguin Books, 2007
- International Standard of Organization (ISO). Acoustics- Standard Tuning Frequency. 16:1975, paperback.
- Neuhoff, John G. Ecological Psychoacoustics. London: Elsevier Academic Press, 2004