# What is the behaviour of pressure waves in a diverging-converging cylinder?

Suppose that you have a plane pressure wave that is travelling through a gas in a cylinder (this may be a pipe for instance) such as the one showed below.

What is the behaviour in a diverging and then converging section? Will there be a reflection of the wave? If yes, where and what kind of reflection?

I read of a reflection of a "negative" pressure wave in the diverging section but I don't uderstand what it means.