In the Romantic period not only was there a marked change especially in the size of the orchestra, there was also a change in the style of music they performed. Composers tended to experiment with the harmonies, leading to the use of discords to heighten emotional effects. Melodies also became more song-like.
The brass section was greatly increased; trombones were now a fixed member of the orchestra. In addition, the valve mechanism and key system were perfected, increasing the flexibility of wind instruments in general. The choice of wind instruments, including woodwind, increased. The number of percussion instruments also grew, allowing more colorful effects. As before, the number of string players had to increase to balance out the orchestra.
One of the more innovative composers was Wagner; he exploited the new developments in wind instruments. Breaking away from the traditional double wind, he experimented with triple wind, and in The Nibelung, he used 4 flutes, oboes, clarinets and bassoons, and 8 horns together with a wide variety of brass instruments for a total of 36 wind players. He also scored for 2 sets of timpani, 6 harps and 64 strings.
In the latter part of the 19th century the orchestra was often enlarged, German composers like Strauss and Mahler having followed Wagner’s cue. French composers, however, used smaller orchestras, emphasizing instead clarity and distinctive timbres.
The 20th century was a time of innovation; traditional views of the orchestra were challenged. John Cage, an American composer, used the piano in such a way as to simulate a whole percussion ensemble. Other composers such as Webern combined the tone sounds of instruments in different ways. Electronic methods were also used to create new sounds and effects.