Stick Time: A Pyramid of Sound

One of the sonic goals that some conductors work toward is what is commonly called a pyramid of sound.  They strive to have a large bass foundation that tapers upward through the tenors, altos, and sopranos, respectively.  It’s a challenging sound to achieve, if for no other reason than male singers are a somewhat rarer commodity.  The choir in this performance from the 2007 ACDA National Conference comes fairly close to a pyramid.  How does the sound affect you? What must be done in rehearsal to achieve this sound?