HENDERSON, Texas (KLTV) - The 171st annual East Texas Sacred Harp Convention is returning to the Henderson Civic Center for a milestone edition, celebrating Christian a cappella music dating back to 1844.

Sacred Harp singing utilizes shape notes, syllables represented by unique shapes, before singers transition to traditional lyrics.

Named after an 1844 songbook called The Sacred Harp, singers sit in a hollow square and face each other instead of an audience."We started our convention in 1855, only 11 years after the book was published," said Robert Vaughn, vice president of the convention.