Question

There seems to be some interference on the phone line. Could you speak __________?

a)louder
b)more loudly

Answer 1

In my opinion it is louder

Answer 2

The answer is, “There seems to be some interference on the phone line. Could you speak louder?”

More loudly is not even a proper word, to begin with.

It is used in some scenarios but it doesn’t give out the proper meaning.

Whereas louder is can easily replace more loud to give proper meaning.