From Ananda Vardanas work DvanyAloka written~9th cent. we find the first written theory of the existence of dhvani in Indian poetry. In his Kasika he gave examples of the different forms of words which create dvani in poetry. But the difference to a word without dhvani is not very clear. For example a metapher usually implies suggestions. In later works we find arguments again the opinion of Ananda Vardana.
So does we find dvani in Indian poetry or not?
I imply that the people,who answer will know about the word dvani in Sanskrit and knows the work sahitya darpana which gives to us the requirements of poetry.