#antiphon

• Antiphon — A material, device, or chemical compound used for soundproofing, noise reduction, or acoustical vibration damping (especially in automotive or construction industries); in Christian liturgical music (theology), it represents a hymn, verse, or psalm sung alternatively by two separate choirs.
• Antiphonary — A liturgical book used in the Christian Church (especially in the Roman Catholic and ancient Byzantine traditions) containing the antiphons, verses, psalms, and hymns designated to be sung alternatively by two choirs throughout the liturgical year.
• Antiphonal — Insulating against noise or damping sound vibrations; pertaining to soundproofing or acoustic reduction. In liturgical or religious music (theology), the term describes a hymnal structure or a mode of vocal performance based on the symmetrical alternation and dialogue between two separate choirs.
• Antiphony — A system of musical or liturgical performance characterized by the alternate singing of two choirs or a soloist and a choir responding successively; a genre of church chant based on this dialogue structure, used since antiquity and consolidated in Byzantine and Gregorian liturgies.