The symphony orchestra has been a fixture of Western concert music since the early 18th century. It grew in size over the course of the 19th century as composers added new instruments and increased the number of players. Today, a professional orchestra is likely to contain about a hundred musicians. These are divided into sections of various sizes based on the instruments they play.
Orchestras include four different types, or families, of instruments. These are known as the strings, woodwinds, brass, and percussion. The instruments contained in each family share a means of sound production, but they come in different sizes and might be made of different materials. As a result, they play in different ranges and with different timbres. Each instrument of the orchestra also has different strengths and weaknesses. Some can play with great agility, while others are better suited to sustained pitches. Some are loud and piercing, suited to prominent solo lines, while others are more subtle. Composers who write for the orchestra must carefully consider the characteristics of each instrument. When the symphony orchestra is used well, however, it is capable of producing an extraordinary variety of sounds.
To hear each of the instruments in the orchestra and see a demonstration of its capabilities, please visit this webpage maintained by the London-based Philharmonia Orchestra: https://www.philharmonia.co.uk/explore/instruments.
All orchestral string instruments produce sound when a vibrating string causes a hollow wooden body to reverberate. On all instruments except the harp, the strings are usually set into motion with a bow, although they can also be plucked. Modern bows are strung with horsehair, while the strings themselves are made out of various metals. Because string instruments are not very loud, there are usually a lot of them in an orchestra.
All woodwind instruments produce sound when the player blows into the instrument, thereby causing the column of air to vibrate. All woodwinds were at one point in history made of wood, except for the saxophone, which has always been made of metal. However, this is not why they are classified together as a group. The reason for this is their similar construction, which constitutes a tube with holes.
All instruments in the brass family feature a cup-shaped metal mouthpiece into which the player blows air in a way that causes their lips to vibrate. As the family name suggests, the instruments are typically made of brass, and, although they come in many shapes and sizes, each essentially constitutes a long tube with a bell at the end. Brass instruments vary in terms of range (which is determined in part by the length of the tube) and the method by which the player controls the pitch.
All percussion instruments create sound when a resonating body is set into motion following an impact. If this description seems vague, it is because percussion instruments employ an extraordinary variety of methods to produce sound. The simplest percussion instrument is a pair of clapping hands, while the most complex require extensive mechanical workings.
