The phaseshift~ object is a 2nd-order allpass filter. It provides a nonlinear delay time as a function of input frequency, emulating the phase shift elements found in analog phase shifter effects. Cascade several phaseshift~ objects to create a more dramatic effect. Since phase shifting by itself is inaudible in most circumstances, usually you'll want to mix the output of phaseshift~ with its input signal, so that frequency cancellations occur as the delayed signal is added to the original signal.