Can someone please correct this sentence?

Spoken, not talked.

I would add that the use of the word "test" is suspect. Did you perhaps mean text? Test is not incorrect, it's just odd.

You can omit the words "than before" as there is no confusion concerning what the new test is more difficult than.

The new test is more difficult because some conversations involve more than two people.

A few errors. Here's a fix,

"I think the new test is more challenging than before with a few changes. For example. in the listening section, the conversation was spoken only by two people however in the new test it is spoken by three people."

Hope this helps you.