The Origins of the Oboe
Instruments related to the oboe

The oboe is a C woodwind, that is, a C major instrument. A lower pitched instrument is the A woodwind, the oboe d'amore, which is pitched in A major. Even lower is the F woodwind, the cor anglais (also known as the English horn), pitched in F major. Those are just two of the relatives of the oboe.
Unlike the oboe bell, the bells of the oboe d'amore and the cor anglais are egg-shaped. People tend to think that the peculiar, muffled sound comes from the egg shape. However, there is a greater relationship with the different tapering of the widths of the interior pipes.

Oboe family instrument ranges

Oboe family instrument ranges

Listen to and compare the different sounds of instruments from the oboe-family.
The song being played on the cor anglais is the famous melody to "Goin' Home," taken from the second movement of Dvořák's New World Symphony. The oboe d'amore piece is from Ravel's Boléro. The oboe piece is Johann Sabastian Bach's "Jesu, Joy of Man's Desiring."

The sound of a cor anglais.

The sound of a cor anglais.

The sound of an oboe d'amore.

The sound of an oboe d'amore.

The sound of an oboe.

The sound of an oboe.

There is also a bass oboe, which produces the lowest sound of any instrument in the oboe family. However, this instrument is rarely encountered. Only a few dozen exist in Japan, and only a few are thought to be produced per year worldwide.
The reason why bass oboes continue to be manufactured is that they appear in Holst's musical suite The Planets. Otherwise, the bass oboe is so rarely used that it could even be said to exist virtually only for a single work.