Uncover the historical basis for arriving at A4 = 440 Hz.
Learn about the arguments for A4 = 432 Hz.
There is a staggering amount of information out there on the ideal frequency for A4 (that’s the A note above middle C). You’ve probably heard of the debate over 432 Hz vs 440 Hz but don’t exactly know what it’s about. Many of us in the world of sound design are especially likely to encounter websites and videos touting the healing power of 432 Hz.
There is a growing trend among YouTube channels posting re-tuned music in which A4 is set to 432 Hz instead of the standard 440 Hz. You might have already stumbled upon a plethora of unsubstantiated claims and conspiracy theories and wondered, could any of this be true? Or even, am I going to have to re-tune my full back-catalog?
In order to get to the bottom of the controversy, I have gone back to the very beginning of tuning standardization and traced its lineage up to the present day. I have searched far and wide for evidence of a deeper meaning to tuning. Having gone down the rabbit hole myself, I will share my findings with you so that you won’t have to.
What Is The Difference Between 432 Hz Tuning and 440 Hz Tuning?
Before we get too far along, it might be helpful to define our terms. The subscript 4 in A4 denotes which octave of A is being tuned. A4 is the A above middle C, which is C4. A4 is, by and large, the pitch most commonly used as a tuning note (also known as a reference pitch) in the history of western art music.
Hz is the abbreviation for Hertz, which is a measurement of frequency named after Heinrich Rudolf Hertz, the first person to provide conclusive proof of electromagnetic waves.
Sound as we perceive it is the result of pressure waves hitting our ears. Pitch varies based on the frequency of those pressure waves, so the most specific way of discussing pitch is by naming exact frequencies in Hertz.
However what is most specific is rarely the most efficient, so pitch is more frequently coded in terms of the letter-names that pre-date the measurement of pitch in Hertz. The common practice ever since the late nineteenth century is to tune one pitch to a specific frequency, typically A4 to 440 Hz, and tune the rest of the instruments relative to that A. This is where the controversy begins.
If all music were written and notated in specific frequencies, there could be no debate as to how the pitches of a piece were meant to be played. So if a composer preferred 432 over 440, they could easily write it that way.
The notation of the past and the MIDI grids of today, however, do not contain specific frequency information. This has opened the door to infinite possibility, leading some to pose the question: Why not tune A4 to 432 Hz? Why not tune A4 to 430.5 Hz? Is there any particular reason to keep A4 at 440 Hz? How did this music sound when the composer wrote it? And on and on.
In effect, the call to tune to A4=432 Hz is a call to slightly flatten A relative to where we normally hear it, and to flatten the rest of the pitches so that they are in tune relative to the new A. Eight cycles per second of difference is barely perceptible to the human ear and most people would not be able to tell the difference without hearing two differently-tuned pieces of music one after the other.
To test your ability to hear the difference, you need only to head over to YouTube when you finish the article where you will be able to find a long list of comparison videos and tests.
The calls to tune A4 to 432 Hz can be grouped into two related but distinct groups.
On the one hand, there are those who would point primarily to the importance of different tuning notes throughout history in historically-informed performance.
On the other hand, there are those who would point to specific physiological impacts related to 432 Hz, either for vocal performers or for those listening. Over the remainder of the article, we will take a look at the context and the arguments made by both groups in order to paint a clearer picture of the debate.
How Did We Arrive At A4 = 440 Hz?
The journey to A4=440 Hz is merely one of the numerous stories of how a vast range of musical practices and materials came to be organized and standardized.
While the music of today would not be possible without these historical developments, one might nonetheless wonder at what our sonic world would be like were it not for the creative destruction of standardization.
In fact, before A4 was standardized at 440 Hz tuning, a separate but similar debate raged over temperament.
Intonation And Temperament
The same Pythagorean intonation that many proponents of 432 Hz tuning point to as justification for a slightly flatter A only produces four consonant intervals: octaves, fifths, fourths, and unisons. This goes a long way in explaining the lack of harmonic variety in the formal medieval music of Europe.
It was just intonation, as formally introduced by the Spanish mathematician and music theorist Bartolomé Ramis de Pareia, that established a tuning system that could be used to create consonant thirds and sixths. The problems with Just intonation were that, in order to make most thirds in the diatonic scale consonant, one fourth, one fifth, and one third could not be in tune.
Pitches outside of a diatonic sequence would also be warped by the tuning up of the thirds in the diatonic sequence, so otherwise enharmonic pitches such as C-sharp and D-flat would no longer sound the same.
While some organs and harpsichords were developed to account for these differences in tuning so as to preserve pure intervals, the more common approach for keyboard and fretted instruments was mean-tone temperament, in which fifths were tuned slightly flat so that major thirds would come through as consonant. This system is most effective within a range of closely-related keys, though, so the further one modulates from those keys, the more drastically out-of-tune the intervals become.
The temperament with which we are most familiar in today’s music is equal temperament, which was made famous by Bach’s The Well-Tempered Clavier yet not widely-adopted until the mid-nineteenth century.
With equal temperament, only octaves are perfectly-tuned, as each semitone within the octave is tuned equally so as to approximate the ratios for each interval. In this way, each interval in each key is equally playable, but none of them are quite perfect except for the octaves. The advantage here is that chromatic instruments like keyboards and guitars can play in any scale without retuning.
Tuning An Ensemble
In the same way that an instrument’s tuning has been subject to intonation and temperament systems as they have developed over time, the tuning pitch for an ensemble has varied widely in time and space. In parts of France in the Baroque era, it was common to tune A4 to approximately 392 Hz, whereas across the Rhine in Germany during the same time period, that same A would be tuned to approximately 465 Hz.
The regionalized nature of Europe prior to the nineteenth century meant that musicians in one town might be tuning to an organ whose A4 was around 431 Hz, whereas musicians in the next town over might tune to a tuning fork with a frequency of 423.5 Hz.
Tuning pitches were a matter of personal preference, whether it be the preference of the organ-maker who chose the lengths of pipes and temperament for the local church organ, or the concertmaster who preferred a slightly sharper A than the one produced by their tuning fork.
Several developments in the 19th century, however, led to a gradual climb in A4 across the board.
Public concerts in larger concert halls were not a major part of the musical experience in Europe until the nineteenth century. The smaller, intimate concert settings of the aristocracy gave way to massive spaces peopled by common folks and traveling orchestras. The moment called for a brighter sound to fill the large spaces, and orchestras responded with a gradual creep upward in pitch.
Instrument-makers were refining their techniques at the time, as well, making stronger, sturdier musical instruments and A strings that could be tuned up as high as 450 Hz without placing undue strain on the instrument or the string.
The consequences for singers, of course, were not insignificant, as in many cases they were singing music written for A4=423 Hz at A4=450 Hz, which put a more serious strain on voices as they reached the upper range of these pieces.
It was in this context, in which pitch proceeded steadily higher seemingly without end, and also against the backdrop of the Second Industrial Revolution, in which nationalism and standardization were on the rise, that discussion regarding the idea of standardized pitch became widespread and reached its crescendo.
Attempts To Standardize
The first successful effort to standardize pitch widely began in 1859 when the French government passed a law setting A4 at 435 Hz, also known as the Diapason Normal.
The standard, legally enforceable in France, gained popularity in other corners of Europe as well, and by 1885 was the subject of the Vienna Conference, in which Italy, Austria, Hungary, Prussia, Russia, Saxony, Sweden, and Württemberg all signed on to the standard. By 1919 it was included in the Treaty of Versailles.
The Stuttgart Conference of 1834 resulted in the recommendation to standardize A4=440 Hz based on the work of Johann Heinrich Scheibler, who invented the tonometer as a means of measuring absolute pitch and theorized A as equal to 440 Hz. In England, efforts by the Society of Arts Committee to adopt this standard in 1850 were derailed by adherents to Philosophical Pitch in a preview of the battle that would one day rage between proponents of 432 Hz and those of 440 Hz.
An international conference in London in 1939 adopted 440 Hz as a compromise between orchestras that had continued to creep upwards in pitch and the French standard of 435 Hz. Though the Royal Philharmonic had resisted the French standard and tuned at 439 Hz immediately prior to this development, the BBC began broadcasting an electronically-produced A at 440 Hz following the conference.
By 1955, the International Organization for Standardization affirmed A4=440 Hz as standard tuning pitch, and then reaffirmed it as part of ISO 16 in 1975. Yet the tendency for many orchestras remains to tune slightly sharp relative to this international standard.
Where Does Verdi Come Into The Debate?
Giuseppe Verdi, as an opera composer, wrote first and foremost for the human voice. As a composer who experienced sufficient notoriety in his own lifetime to see his works performed across Europe, he was also able to recognize the disparities in pitch between opera houses in France. Here, the pitch was standardized at A4=435 Hz in 1859, and his home theater La Scala in Milan, where the orchestra tuned to A4=451 Hz.
Verdi wrote vehemently in support of the standardization of a lower pitch in an effort to preserve the voices of his singers. It is clear from his letters that he would have preferred an A4 aligned with a middle C, or C4, equal to 256 Hz, which is also known as the basis of Scientific pitch, but the actual pitch of A4 based on this whole-number tuning of C4 and equal temperament ends up being around 430.5 Hz.
Proponents of Scientific pitch prefer it because it allows middle C to remain an even number and, more importantly, a power of 2, which makes for easier math in ratios and scientific calculations.
Pythagorean tuning would result in Scientific pitch as well as A4=432 Hz, but Pythagorean tuning, as you will recall from earlier in this section, also results in dissonant thirds and sixths, which would really put a damper on the harmonic structures of romantic era Italian opera.
Verdi wrote in favor of 432 Hz but also wrote that it was close enough to the French standard that he would support the adoption of the latter. His later works premiered at the French standard.
All of this is to say that Verdi’s position in the debate was that of someone writing for the human voice who opposed the upward creep in pitch. While other instruments may be able to handle this, the human voice has upper limits that vary from person to person. The slightest increase in pitch could push someone out of their singing range.
The Arguments For A4=432 Hz
Now that we have contextualized our current debate, we can address each point of the argument for A4=432 Hz with an underlying understanding that the process of standardization occurred over time and for reasons situated historically.
Based on this understanding, you, the reader, can evaluate each argument and the evidence supporting it so as to reach your own conclusion. The following sections will present all of the scientific and pseudo-scientific reporting I have been able to find up to the date of publication, along with a relatively neutral and transparent evaluation of their credibility.
Lyndon LaRouche and the Schiller Institute
The most prominent name associated with 432 Hz in the twentieth and twenty-first centuries is Lyndon LaRouche, a quasi-politician, cult leader, and conspiracy theorist who died in 2019. His work is carried on by his wife, Helga Zepp-LaRouche, and the Schiller Institute, which was founded based on his philosophies.
LaRouche is a truly fascinating character whose political life has run the gamete from Trotskyist organizing in the West Village of New York City to supporting the Reagan presidency and later the Trump presidency.
Entire articles have been written about his political life and more still about how he utilized specific forms of psychosis-inducing abuse to control his followers in the National Caucus of Labor Committees.
Further, LaRouche does not make the most credible witness for a 432 Hz reference pitch, as he is a convicted fraudster. LaRouche served some time in federal prison for federal charges related to fraud brought on him by the one and only Robert Mueller in the late 1980s. Nonetheless, he has been the most outspoken proponent of 432 Hz in recent history.
LaRouche and his followers have pointed to the 1939 Conference in London to draw the connection between 440 Hz and Nazism. In case you’re wondering how these two things are possibly related, the reasoning is that Joseph Goebbels, as Propaganda Minister with full oversight of the German broadcast system, would have had a hand in appointing the representative of Germany to the conference that standardized A4 = 440 Hz.
To suggest that the Nazi Minister of Propaganda was the mastermind behind the international standardization of pitch, however, is giving Goebbels a bit too much credit.
US makers of musical instruments had made the switch to 440 Hz as an informal standard as early as the 1920s, and many ensembles performing in radio broadcasts were already tuning to 440 Hz well before the conference. The push to standardize in 1939 came from the radio broadcast industry as a whole, of which Germany was merely one small part.
LaRouche suggested that music had been utilized as a form of warfare and psychological control in the United States, particularly citing The Beatles as agents of the British Psychological Warfare Division. He suggested that one way of resisting the influence of Rock and Roll would be to tune musical instruments using “Verdi tuning,” the A4=432 Hz reference pitch the composer favored.
LaRouche enjoyed little success in convincing US orchestras to tune down to 432 Hz, but the Schiller Institute’s 1988 campaign to have A4=432 Hz standardized in Italy managed to recruit the likes of Luciano Pavarotti and Plácido Domingo before fizzling out.
Scientific Studies Exploring 432 Hz
The Italian Studies
The research community has responded and conducted numerous studies on whether 432 Hz is better than 440 Hz. Four studies in particular were conducted by Italian researchers:
I have grouped the Italian studies together for two reasons: 1) Italy was the home of the strongest push for making A4=432 Hz a standardized reference pitch and 2) the results of the studies suggest similar conclusions.
Each of these studies utilized three experimental groups: a control group with no musical intervention, a group with a musical intervention tuned to 440 Hz, and a group with a musical intervention tuned to 432 Hz. In each study, the researchers observed a statistically significant positive effect resulting from the 432 Hz intervention that was stronger than that of the 440 Hz intervention.
The 2016 and 2019 studies found that 432 Hz musical interventions were more effective at lowering heart rate and blood pressure than 440 Hz musical interventions. The 2020 study found that listening to 432 Hz musical interventions could be linked to better sleep.
The 2017 study dealt with weight gain in rats. It found that musical interventions in both tunings could be linked to weight gain among rats, but that the weight gain was greater among rats exposed to 440 Hz.
I will leave it to you, the reader, to decide how that finding might impact your pitch preferences. One last common feature among the studies was their authors’ insistence that further research at a greater scope needed to be conducted, and that these were limited, preliminary results.
The findings of this particular study similarly point to the effectiveness of music in lowering anxiety levels in oral surgery patients, as measured through salivary cortisol levels, and further suggest that the effect of lowering these cortisol levels is stronger in the 432 Hz musical intervention than in the 440 Hz musical intervention.
An interesting aspect of this study is that patients reported no difference in their perceptions of their own anxiety levels upon listening to the different musical interventions.
The authors of this study included similar statements at the end of the report suggesting that this sort of research is somewhat controversial due to its preliminary nature and the lack of established protocols. Just like in the previously mentioned studies, the authors recommend widening the scope of the research in future studies.
Listener Perception Studies
Professor Trevor Cox wrote a post on his acoustical engineering blog in 2013 entitled Pitch shifting to 432 Hz doesn’t improve music. His findings are based on research he conducted with the help of a few hundred participants who chose a musical passage based on a preference from a selection of re-tuned versions of the same piece of music.
Both researchers found a preference for the original tuning of 440 Hz among their participants. These studies are departures from those mentioned above, as they measure audience listening preference as opposed to biometric data such as heart rate, of which the listener may be unaware. In these cases, there was a clear demonstrated preference for the standard 440 Hz recordings out of all of the different frequencies.
Conclusion and Questions for the Reader
Now that we have traversed the great history of frequency standards it is left to us as listeners, producers, and otherwise students of sound to determine which tuning we like better. The important thing is that you now know the science and reasoning behind both standards so you can better separate fact from fiction.
The studies linked above ask interesting questions and go about answering them as best as they can, but are by no means conclusive. Even if they were, I find myself asking the question, Is my goal always to decrease my listener’s heart rate?
The musical experience is so multifaceted, it strikes me as a fool’s errand to characterize it solely based on biometrics like heart rate and blood pressure.
Even if we were to break the experience of listening to music down into measurable responses in the human body, the most dynamic music should trigger responses all over the map, from deep, serene calm, to a spiked heart rate and brain waves firing off in all directions.
The question here is who wins and who loses when we standardize pitch? It’s an interesting one, as the answer changes throughout history. Pitch standardization has always impacted vocalists and instrument makers in a more material way than those listening to the products of their work, as a higher A4 puts a greater strain on the human voice and other musical instruments.
In the present day, however, when pitches can be shifted after the fact with the help of digital software, the consequences of a different tuning pitch are far less impactful.
That being said, Lyndon LaRouche and everything with which he has come into contact, including 432 Hz, carry a great deal of baggage. Moreover, the language surrounding 432 Hz has shifted in a definitively conspiratorial and mystical direction, featuring claims with no basis in scientific literature or music history. These claims make appeals to human emotion
For that reason, when it comes to experimenting with alternative reference pitches, I personally see no reason why not, but I would also suggest it should be for some reason other than anything having to do with Lyndon LaRouche and unsupported pseudo-science.
Your Music, Your Choices
Speaking from experience, a lazy guitarist or violinist showing up to a solo gig without a tuner has probably played a show at a reference pitch of 432 Hz and been none the wiser.
Their audience might have enjoyed the music or not, equally unaware of having experienced a slightly detuned performance. That same musician, upon getting to their orchestral gig the next day, would have to retune to the reference pitch of their ensemble, however, in order to keep their job.
Standardization has its uses where it has its uses, and outside of these contexts, why limit the tools and resources at one’s disposal? Harry Partch is just one example that comes to mind of a musician who found a lot of creative space in between the generally-accepted frequencies of equal temperament.
None of the major drivers of tuning standardization – namely acoustic instrument design, vocal registration and health, or the tuning of radio signals – remain consequential to today’s bedroom producer or casual listener.
For this reason, I would answer the question “440 Hz or 432 Hz?” with “Why not both?” and I would invite you to answer the same question however you see fit.
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