The clarinet part should therefore be in the key of A:

Imagine, for example, that our sample oboe part is in the key of G. We transpose key signatures in the same way as notes. Unfortunately, things are usually a bit more complicated. If, for example, the oboe is supposed to play a G, we must write an A for the clarinet:

So we need to raise the pitch by a whole step. The clarinet, however, is a B-flat instrument ( see Nomenclature below). Like the flute, the oboe is a concert-pitch instrument. So we need to transpose our oboe part for clarinet. Fortunately, a clarinet player is available.

Suppose we have an oboe part, but no oboe player. For example, maybe a saxophone will play a French horn part. And sometimes we compensate for missing instruments by substituting others. If the player isn't used to 'sight-transposing' we'll need to transpose the part. We often have parts for A clarinet instead of B-flat clarinet, and for C trumpet instead of B-flat trumpet. That is, we must transpose the flute part. (So we call the flute a 'concert-pitch' instrument.) On the other hand, when a clarinet plays C we hear a B-flat! This means that if we want a clarinet to play a flute part, we must write pitches that are higher by just the right amount. For example, when a flute plays a C we really hear a C.

Not all instruments refer to the same pitch with the same names. Examples: A to Bb clarinet | F horn to saxophones | E horn to alto sax Introduction

B flat clarinet