PRESS PHOTO BY LORI PATRICKThe power of the human voice was in evidence during the Pentatonix Grandstand concert at the 2017 Great Allentown Fair. The 90-minute, 18-song concert showcased the quintet's a cappella vocals before a reported sold-out crowd of 10,536 on Sept. 2. Copyright - Contact: lori@expressions21.com LORI PATRICK