When it comes to audio complaints, what tops the list is feedback.
If you are blessed to be in a modern facility, well designed for contemporary music, both architecturally and acoustically, then feedback might not be a major weekly issue.
For the rest of us, however, feedback is something that we struggle with just about every week.
Ringingthat sustained sound you hear when someone speaks and then goes away when the speaking stopsis simply another form of feedback that hasn't crossed the line into being self-sustaining.
There are a variety of causes of feedback.
The simplest would be when a microphone is directly picking up the sound from the loudspeaker at a level that builds over time (sometimes very quickly!), and creates that dreaded squeal.
However, there are also indirect causes that exasperate the feedback problem.
As we discussed in previous articles, the acoustical characteristics of your room can impact feedback problems. Sound from the loudspeaker system can bounce off the hard surfaces in your room - such as the walls, ceiling, or even the wooden backs of pews. If sound bounces and then hits a microphone in the room, at certain frequencies these bounces near the mic will add up causing ringing or feedback. If you fix the acoustical issues, your feedback problems can be greatly lessened.
Another problem is having too many microphones open at the same time.
The more microphones you have open, the lower your gain-before-feedback (how loud you can push an input before feedback begins) will be.
For microphones that are particularly susceptible to feedback, such as a podium mic, you may find that having any microphones open for the band when you turn on the podium mic will make the podium mic almost unusable.
Next article, we'll talk about some of the ways to deal with feedback.