Why the oboe?
This is a very sensitive subject. There are many theories around about this question, with passionate adherents and detractors to every theory. Here are some of them:
The oboe has the most piercing sound in the orchestra, and can be heard well by everyone on the stage.
OK, but why not use the trumpet or the trombone instead? They are certainly easier to hear than the oboe.
The oboe is the instrument the least affected by fluctuations in temperature and atmospheric conditions.
Then why not use the “weather proof” xylophone? In fact, according to the son of Jean de Vergie, an oboist with the Boston Symphony Orchestra in the ’40s, “oboes look like undernourished clarinets…and they are highly temperamental. Easily knocked out of tune by cold, heat, moisture, or the slightest of bumps, they must be handled with maniacal care. Let an oboe get chilled, and if it doesn’t crack it goes sour, and when warm again it sheds keys.”
The oboe is the least flexible instrument in the orchestra, and cannot be tuned.
This one infuriates oboe players! In reality, the oboe can be tuned in several ways, not the least of which is the oboist’s skill in micro-tuning notes on the fly to match the musicians around him or her.
The truth of the matter is probably mostly due to circumstances of history. In the Baroque period, the oboe was the first instrument to be added to the standard all-string orchestra. I can easily imagine the string players giving the oboist the responsibility of establishing the A to avoid arguing among themselves about the pitch! Today, most oboists use an electronic tuning device to make sure that they are giving the correct A. Therefore, no one can dispute it. In an extreme version of this practice, some orchestras are now using an electronic tone generator precisely set to the official pitch of the group. But even here, tradition is observed: the oboist has the honor of turning the machine on and off!
What if there is no oboe in a particular piece of music?
In the case, the job goes to another woodwind or brass instrument, often the clarinet or bassoon. In the case of a string orchestra it will generally be the first cellist who will give the A. Why? I don’t think anyone really knows!
What about instruments with a fixed pitch?
Pipe organs, mallet percussion instruments (xylophone, marimba, glockenspiel, et al), and pianos and celestas. They very likely will be tuned to a different A than the orchestra’s standard. In this case, the A will often be given first on one of those instruments, the oboist will listen to it, and then reproduce the A at that new pitch so the orchestra can retune their instruments.
So, the next time you see an oboist giving the A to the orchestra, you are watching history and tradition in action!