Why does the orchestra tune to the oboe?

Circumstances of history, mostly, but also acoustics. The first orchestras (in the late 1600s) were mainly string instruments. A pair of oboes was sometimes used to strengthen the first and second violin parts. Soon composers were writing separate parts for the oboe, exploiting its singing tone as a contrast to the violins. The bright, rather penetrating sound of the oboe was easy to hear, and its pitch was more stable than gut strings, so it was natural to rely on it for tuning (One can also imagine it settling, or preventing arguments. Twenty string players squabbling over a tuning note, then asking the oboist to intervene). Other instruments drifted in and out of the orchestra – flutes, bassoon, French horns, clarinets – before its instrumentation became relatively standardized as we know it today. But oboes were almost always present, so they became the standard instrument for tuning.

There are exceptions. Sometimes a composer chooses to replace the oboes altogether with the mellower clarinets. In that case, the clarinet becomes the de facto tuning instrument. Then there are keyboard instruments like piano, harpsichord or organ. The entire orchestra must tune to them, but the oboe still plays a role. When a keyboard instrument joins the orchestra as either a featured instrument or just a section member, the oboist listens to the ‘A’ played by the keyboard, matches it, and plays it so the rest of the orchestra can hear. And what if there is no keyboard, no oboe, no clarinet – just strings? Then the concertmaster pre-tunes his or her A string to A=440 Hz and plays the note for everyone else to hear.

Orchestras always tune to ‘A’, because every string instrument has an ‘A’ string. The standard pitch is A=440 Hertz (440 vibrations per second). Some orchestras favor a slightly higher pitch, like A=442 or higher, which some believe results in a brighter sound. If you ever played in concert band, you’ll remember that you always tuned to B flat. This is because most of the band instruments are actually pitched in B flat, and so this is their natural tuning note.

Here’s a little secret you’ll never know as an audience member. Oboes can play sharp or flat, just like any other instrument. But every oboist uses a little electronic meter to ensure that their ‘A’ is exactly right. In fact, some orchestras – even major orchestras – have gone ‘modern’ and use an electronic device to sound the tuning note. Even then, tradition is respected: it’s the oboist who turns the device on for tuning, and off when the task is completed!