It is just a couple of minutes before the concert begins. The members of the orchestra are assembled on the platform, chatting amiably to each other, waiting for the leader of the orchestra to join them. Last to appear will be tonight's conductor. The deputy or assistant leader gets to his feet. A hush settles quickly over the players. A solitary plaintive note – A above middle C – is sounded by the principal oboe, a note which spreads rapidly across first the woodwind and then the string sections, and is soon joined by the other instruments and by other notes: the orchestra is tuning up. Why did they wait until now to do it? Could they not have tuned up earlier backstage? Why that particular note, and why by the oboe? This Entry will attempt to answer these questions and explain how it all came to be.

What is Pitch?

When we hear the oboe play that note, what we perceive as a sound is actually a series of pressure waves impacting on our eardrum. The less time that elapses between each successive wave, the higher the frequency of the note seems, or what is called musically, its pitch. In the case of the note A above middle C (A₄), there are about 440 of these waves impacting on our eardrum every second, so its frequency is 440Hz. Musically, we say the note is A440.

What Came Before Standards?

For a thousand years, bands of musicians have known that to avoid their audiences gnashing and grinding their teeth, it is necessary for them to be in tune with each other – middle C played on one instrument should sound as nearly as possible at the same pitch as middle C played on another instrument – but beyond that there was little or no standardisation. It was rather like clocks before the coming of the railways: time was a local standard, with local clocks being set to match some chosen reference such as that shown on the nearby church tower.

In the 1830s, the German physicist Johann Heinrich Scheibler (1777-1837) invented one of the first accurate methods for measuring musical pitch. His device – called a tonometer¹ – consisted of 52 forks tuned from 219.6Hz to 439.5Hz, measured at 69°F. It used the method of counting the number of audible interference beats between a given note and its nearest tuning-fork in the device.

Is it Warm in Here?

One of our earlier questions was why doesn't the orchestra finish its tune up backstage before coming onto the platform? Well the fact is that temperature has a marked effect on pitch, so they need to fine-tune their instruments in the environment in which they will perform rather than the backstage area. What effect temperature has depends on the instrument. A perfectly tuned woodwind instrument will sharpen – the pitch will be a little higher – if it is taken into a warmer environment than it was tuned in. Conversely, it will flatten – the pitch will be a shade lower – when taken into a colder environment. With stringed instruments, their pitch also varies with temperature but in the opposite direction: the strings expand as the temperature increases, lowering their tension, thus lowering their pitch and making them sound flat.

Interesting it is the temperature of the air inside a brass or woodwind instrument, rather than the temperature of the instrument itself that counts. This is due to the fact that the velocity of sound in air varies with temperature: at 15C it is about 340 metres/sec; at 20C, 343 m/s and at 25C, 346 m/s. This would change a note pitched at 440Hz at 15C to a note pitched at 444Hz (about 15% of a semitone higher) from the same instrument at 20C.

Why the Oboe?

Obviously none of the stringed instruments are of any use as a tuning reference; they all need some other primary or secondary standard to tune to. At first sight the oboe is an odd choice as a reference instrument. You might think that something that generates a pure tone with no harmonics, just as a tuning-fork does, would be the ideal choice, whereas the oboe has a rich harmonic spectrum comprising all the integer multiples of the fundamental tone. Using a tuning-fork is impractical since it is inaudible unless you are very close to it. Of the woodwind instruments, the flute comes closest to being a loud tuning-fork, but it is the oboe which is used, partly for historical and partly for practical reasons. On a historical note (pardon the pun) oboes - usually a pair - were the first instruments to be added to the strings-only orchestras of the early 1700s, and so were always present.

From a practical viewpoint, the oboe is a mid-range instrument, with a range from B-flat₃ (about 233Hz) up to A₆ (1,760Hz). Its sound is distinctive, enabling it to carry very well across the orchestra while it is tuning up. The bassoon shares this characteristic but its A is an octave lower, below the range of the upper strings. The oboe's position towards the centre of the orchestra is also useful. It can produce a repeatable A440 note relatively easily, often checked these days against an electronic tuner.

To be honest though, today the oboe retains its reference role probably more by tradition than by any real advantage possessed by the instrument.

French Pitch

As early as the 1600s, the composer Michael Praetorius had noted that instrument makers tended to produce their instruments at a pitch that by brilliance or sonority favoured them. In 1814 at the Congress of Vienna, the Russian Emperor Alexander I presented a new set of significantly sharper instruments to one of the three household regiments of Vienna. One of the Grand Dukes of Austria presented a new set of instruments to another of the household regiments; these were sharper still. Since these regiments were a principal source of musicians for Vienna's opera houses, they were obliged also to raise their pitch.

During the first half of the 19th Century, average pitch had been rising progressively. In addition to the instrument makers' competitiveness, there seems to have been two further drivers to this trend: increasing size of performance spaces and improvements to the strings of stringed instruments enabling them to be more tightly stretched. The further the listener is away from an instrument, the quieter it seems, especially for higher notes. The more remote listening position in larger concert rooms brought about a trend towards brighter-sounding instruments that would previously have seemed too bright in a small chamber environment. Increasing the tension of stringed instruments enabled a higher pitch to be obtained, but in many cases it was necessary to modify these instruments to allow them to cope with the additional strain.

Singers were often the hardest hit by this progressive rise in pitch and they complained bitterly about the damage being done to their voices by forcing their top notes ever higher. In 1859, the French government decreed that a standard pitch of A=435Hz would henceforth apply throughout the country. This frequency was chosen as a compromise between the lower pitch common in Mozart and Haydn's time and the ipso facto standard pitch to which it had risen by 1859. This new standard was commonly referred to as French pitch or by its French title diapason normal. A standard tuning-fork was lodged at the Paris Conservatoire.

Philharmonic Pitch

French pitch might have been law in France and international singers keen to see it adopted everywhere, but the decree had no jurisdiction outside French territory. In England, the ipso facto ruling body of musical practice was the Philharmonic Society. Founded in 1813 to enable the performance of orchestral music in London, it was what the Philharmonic did that set the mark, or in this case quite literally the pitch. At the time of its founding, A424 was the norm, but by about 1820, conductor Sir George Smart had approved an increase to A433. In 1846, at the first UK performance of Mendelssohn's Elijah at the Birmingham Festival on 26 August, the pitch employed was A453. Something around this pitch continued during the 'reign' of Sir Michael Costa as conductor of the Philharmonic Orchestra between 1852 and 1874².

Doubtless as a signal, on 13 January 1885, it was announced "the Queen [Victoria] has sanctioned the adoption of the diapason normal for her private band, and that this will in future be used at the State concerts." Six months later, on 20 June, a "Conference on Musical Pitch" was held at St James's Hall, chaired by Professor Sir George Macfarren³, "to consider the desirability of a standard musical pitch for the United Kingdom." The meeting was initiated by an official note from the Foreign Office regarding difficulties experienced by musicians playing in different countries.

The subject had been looked at 25 years previously by the Society of Arts⁴. A committee, comprising almost 50 of the leading scientists, musicians, instrument makers and educators of the day, was appointed in 1859, and the Society met on 8 June 1860 to discuss the committee's report. They recognised the desirability of a standard pitch and favoured C512 (equivalent to A430), but recognising that this was likely to be too low to be accepted, proposed a compromise standard of C528 (A440). Failing to mention it, they were working with the older practice of just intonation rather than equal temperament, so when the latter was assumed by everyone else, C528 was converted to a value nearer to A444. The meeting voted in favour of the manufacture of a standard tuning-fork; this was produced by Henry Griesbach⁵, but was a little sharp with a measured pitch of A445.7. In the end there was consensus on the need for a standard pitch at or near A440, but nothing concrete was actually achieved.

The Foreign Office had become involved because Her Majesty's Ambassador to Belgium had passed information to them that a commission chaired by the Principal of the Brussels Conservatoire had recommended to the Belgian government, and to which the (Belgian) king had agreed, that the French diapason normal be adopted in all institutions subsidised by the State, and in all military bands, schools and theatres.

The star tenor Charles Santley told the meeting that he found great difficulty in trying to sing a piece which he was quite accustomed to sing at the Opera in one pitch, at a different pitch at St James's Hall. He favoured a uniform pitch throughout the musical world, but lower than the current standard.

One particular difficulty in lowering pitch was noted for organs, whose pipes may be shortened (and hence sharpened) but not flattened. One proposal of how this difficulty could be surmounted was to remove the highest pitched pipe, move all the others up one place and provide a new pipe at the bottom end, before retuning the entire instrument up to the new pitch.

It was of general agreement that a standard pitch should be adopted, but whether the French pitch was of sufficient widespread use was doubted, not to mention the hardship likely to be caused to musicians whose instruments would be rendered obsolete. The country's military bands conformed, by and large, to a single, albeit higher, standard, which on cost grounds – a figure of £40,000 for the Army alone was mentioned – they simply would not change. Experts argued that the effect of the period of upward drift in pitch on violins such as those by makers like Stradivari and Amati could well be detrimental as a result of the strain placed by the additional string tension. For reasons of self-interest, tenors and sopranos expressed support for the decrease in pitch while contraltos wanted to retain the higher pitch: with the reduction, sopranos could perhaps squeeze another semitone at the top of their range, while conversely, the contraltos might lose something at the bottom of theirs.

Three resolutions were voted on and carried:

1. "That it is desirable to fix a standard for musical pitch throughout the United Kingdom which may accord with that of other countries.";

2. "That in order to annul the great inconvenience consequent on the discrepancy of pitch in this and other countries, it is desirable to adopt the French normal diapason of 528⁶ double vibrations for C, third space in the treble.";

3. "That steps be at once taken for securing the adoption of the standard pitch in the principal orchestras; and also if practicable, by the regimental and other bands of the British Army."

A committee comprising 22 physicists, practical musicians, vocalists, composers, players and instrument makers was appointed to fulfil these resolutions. Their first action, to attempt to get the pitch of military bands standardised by the War Office, was rebuffed resolutely by their Commander-in-Chief, the Duke of Cambridge, who cited "financial and other difficulties too great to be overcome". Already by October 1885 the committee had given up and dissolved itself.

The Philharmonic Society finally adopted diapason normal in 1895, but by a rather devious sleight of hand at A439 rather than A435. It was commonly, though mistakenly believed in England that the French decree had specified its standard at a temperature of 59°F (15C), which the Philharmonic Society recalculated for the more typical UK concert room temperature of 68°F (20C).

Where We Are Today

The advent of radio broadcasting brought concert performances from many countries in Europe and North America to a listening public. With it came an ever more pressing need for standardisation. In May 1939, an international conference in London agreed the present standard of A440, which the BBC began broadcasting as a tuning standard. A440, rather than the close A439 was chosen, as in the interests of accuracy, the tuning note would be generated electronically from a high-precision 1MHz piezo-electric crystal⁷ – A439, being a prime number, would be considerably more difficult. The A440 standard was endorsed by the British Standards Institute in 1939 and by the International Standards Organisation in 1955 and 1975.

So the next time you see or hear that oboe player setting the pitch for his or her orchestral colleagues, remember it isn't by accident that the note is at the pitch it is, but then it isn't entirely by design either.