Question

Determine the part of speech for the word ring as it is used in the sentence.

Of course, just as he reached the top of the stairs, he could hear the ring of the telephone from down below

Answer 1

It is a noun because it is an object.
I hoped this helped :3

Answer 2

The word ring is used as a noun in this context.
What could he hear? The ring of the telephone from down below.
It is used as the direct object in the sentence, which is why it has to be a noun - verbs cannot be used as objects.