Ānandavardhana (820–890) was the author of Dhvanyāloka, a work articulating the philosophy of "aesthetic suggestion". The philosopher Abhinavagupta wrote an important commentary on it.
Ānandavardhana is credited with creating the dhvani theory. He wrote of dhvani (meaning sound, or resonance) in regard to the "soul of poetry." "When the poet writes," said Ānandavardhana, "he creates a resonant field of emotions." To understand the poetry, the reader or hearer must be on the same "wavelength." The method requires sensitivity on the parts of the writer and the reader. The complete Dhvanyāloka together with Abhinavagupta's commentary on it has been translated into English by the eminent sanskritist Daniel H.H. Ingalls and his collaborators.
Modern Sanskritists have a very high opinion of Ānandavardhana. Commenting on Ānandavardhana's Dhvanyaloka, P.V. Kane writes that "the Dhvanyāloka is an epoch-making work in the history of Alaṅkāra literature. It occupies the same position in poetics as Pāṇini's Aṣtādhyāyī in grammar and Śaṅkarācarya's commentary on Vedānta". And Daniel H.H. Ingalls calls Ānandavardhana 'the most brilliant of all Sanskrit critics'.