The Ypakoë (Greek: Ύπακοή, from the verb υπακούω, "hearken" or "give ear", to "respond"; Slavonic: Ўпакои) is a troparion chanted at Orthros (Matins) and the Midnight Office on Great Feasts and Sundays throughout the liturgical year in the Eastern Orthodox Church. The Ypakoë which is chanted on Sundays is found in the Octoechos and there are eight of them, according to the Tone of the Week. The Ypakoë used at one of the Great Feasts will be written in the tone of the hymnographer's choice. The hymn occurs in several places, depending upon the day and the service: