Eastern Orthodox music
Orthdox music developed from the medieval Byzantine sacred chant of Christian Churches following the Orthodox rite. This tradition, compassing the Hellenistic world, arose in Byzantium from the establishment of its capital, Constantinople, in 330 until its fall in 1453. Byzantine music drew on the artistic and technical productions of the classical age, influenced by Jewish music, and inspired by the monophonic vocal music that developed in the early Christian cities of Alexandria, Antioch and Epheus. Thus, Orthodox music developed from a Greek musical background. 
Orthodoxy has spread and its music adapted to its various regions, however, Orthodox music has retained its distinctive features and differs from European music. On important occasions, singing is used in place of chanting, thus some things which are chanted at minor services are sung at more important services. Singing is as varied and multi-faceted in its forms as chanting and vestments, changing with the Church 'seasons' of commemoration thus singing during Great Lent is always somber and during Holy Week nearly becomes a sorrowful dirge while during Pascha (Easter) and the Paschal season the notes are high and quick and as joyful as they were sad during Lent. The power of music is used to its full effect to bring about spiritual renewal in the listeners.
Over the centuries Orthodox church music has expanded and become more elaborate. The Church uses eight 'tones' or 'modes,' which are broad categories of melodies. Within each of these tones are many small more precise melodies. All of these tones and their melodies rotate weekly so that during each week a particular tone is used for singing music.
Byzantine notation, also called Chrysanthean notation (Chrysanthean of Madytos being one of its inventors) is a neumatic system of musical notation used for rendering Byzantine chant into written form.
Byzantine notation is very different from Western notation in most ways. The following comparison assumes familiarity with Western notation. Western notation is based upon a staff, where the location of the note with regard to the staff determines the pitch, regardless of the previous note. Byzantine notation, on the other hand, is relational; the note is dependent on the previous note and the symbol itself, which specifies the interval from the previous note. Whilst there are differences in speed and in whether a certain note should be flat or sharp in Western music, Byzantine music has this down to a highly complex form of art, employing specific tones which always have a specific note being sharp or flat. One near-similarity is the scale. In Western music, Do (the start of the scale) corresponds to the Byzantine note Ni, which is a note below the start of the Byzantine scale. Byzantine music has eight tones (or modes), sometimes associated with particular "moods" (though the notion that the music is designed to be emotional would certainly be distasteful to the saints who developed it). Also, much of Byzantine chanting can be done without use of written music, due to the use of original melodies (Greek, αυτόμελον) and improvisation. While there are tens of thousands of hymns in Byzantine music, they are all based on less than two hundred original melodies.
Russian Orthodox choral music is known for its Oktavists, singers capable of an exceptionally deep-ranged basso profundo. This voice type has a vocal range which extends down to A1 (an octave below the baritone range) and sometimes to F1 (an octave below the bass staff) with the extreme lows for oktavists, such as Mikhail Zlatopolsky or Alexander Ort, reaching C1.
Slavic choral composers may occasionally descend to lower notes such as F1 in "Kheruvimskaya pesn" (Song of Cherubim) by Krzysztof Penderecki, G1 in "Ne otverzhi mene" by Pavel Chesnokov or B♭1 in the Rachmaninoff All-Night Vigil, although such notes sometimes make an appearance likewise in repertoire by non-Slavic composers (e.g. B♭1 appears in Gustav Mahler's Second and Eighth Symphonies). Russian composers often make no distinction between a basso profondo, an oktavist or a contrabass singer.
Sergei Kochetov, Vladimir Miller, and Mikhail Kruglov recorded a number of classic Russian folk songs and similar music, singing them in a low-pitched key to invoke the old oktavist tradition which dates back to the Tsar's court.
- Eastern Orthodox songs
- Gospodi, pomilui (Lord, Have mercy) - playlist 1
- Gospodi, pomilui (Lord, Have mercy) - playlist 2
- Greek Orthodox Christian Byzantine Music
- Russian Orthodox Choir Chanting Choral Vocal Top 10 Collection
- Beautiful Russian Orthodox Choir Chanting Choral Vocal
- Valaam Brethren Choir
- Russian Basso Profondo: The Lowest Voices
- The Power of the Russian Oktavist