echos

(Greek: "sound", pl. echoi ; Old Church Slavonic: "voice, sound") the name in Byzantine music theory for a mode within the eight-mode system (oktoechos), each of them ruling several melody types, and it is used in the melodic and rhythmic composition of Byzantine chant ("thesis of the melos"), differentiated according to the chant genre and according to the performance style ("method of the thesis").

the eighth studio album by Switzerland-based Gothic rock band Lacrimosa.