Why are there timpani, cello and viola in the national orchestra?

The result of making foreign things serve China.

However, to correct one point, the most common western instruments in national orchestral music are cello, double bass and timpani.

Viola is rare.

Traditional folk music lacks bass. Most of them are high-pitched and bright instruments with high sound recognition.

Such as suona, flute and pipa.

The bass part can only rely on middle Hu, low Hu, big Ruan, bass sheng and so on.

But these so-called bass instruments are small in size, but they are very distinctive and independent.

So do percussion instruments.

Cello and double bass in western musical instruments have long sound lines and are easy to play smooth melodies.

Can provide a very solid foundation for music.

Timpani is louder and more convenient than traditional paigu and Hua Pengu.

I can't elaborate on many benefits, but I hope I can understand them.