Prentiss L. Thompson breakdown the usages of utilizing a omnidirectional mic. The do's and don'ts. Omnidirectional mics pick up sounds from all directions and should be mounted 5 to 8 inches (12 to 20 cm) below the pastor’s mouth.
Unidirectional mics with a cardioid or supercardioid polar pattern offer a greater degree of protection from feedback problems, but are more susceptible to plosives, wind noise and proximity effect.