“There are people coming from all over the country!” exclaims Rachel Hall, co-chair of the Keystone Sacred Harp Convention. Two full days of singing from a book first published well over a century and a half ago has people booking motel rooms up and down Baltimore Pike near St. Philomena’s church hall in Lansdowne, where approximately 150 voices will be raised. “Loud!” adds Hall, assuring newcomers to shape-note singing that there is little chance you’ll be heard. Shape notes date back centuries to early singing schools, with each solfoge note of the scale being given a different shape to ease sight-reading. When groups gather, they form a “hollow square” with the four voice parts of a typical choir facing one another. No pitch pipes or other instruments tune the group — that’s done by the song leader. Who is that? Whoever’s turn it is. (When you register, you are asked if you’d like to lead a song). They stand facing the tenors, who always have the melody. 

Sat.-Sun., Jan. 26-27; free St. Philomena’s Hall, 41 E. Baltimore Pike, Lansdowne, 215-605-1621, pennsylvaniasacredharp.com.