Microphones are THE essential component in just about every live situation. They are also one of the more difficult things to set up compared to other components used and once they are set up, the sound person must carefully monitor them because they now have to watch the users.
(The mic shown is an Apex podium microphone with a base attached - and an XLR connector built into the back. It's a low profile, matte black mic which works great with my Sony ECM windscreen. It hides nicely and, with a little EQ magic, it's sounds great! The talker shown had great mic technique!)
Once the sound person 'rings out' the loudspeakers, it's up to the user to work around the limitations of the system. There is a lot to consider for the sound person here, including microphone type, loudspeaker orientation and position of the 'source' (or presenter). The sound person follows a set of guidelines, which are well established in the audio industry, to maximize what we call 'gain before feedback' - or, getting the loudest, best quality signal from a sound system.
Once the sound system is set up properly, the person behind the microphone must do their part and speak directly into the microphone to get the loudest, clearest sound. If the speaker ('presenter') cannot be heard throughout the room, a series of checks must be performed to find out why - and fast, as an audience will not tolerate poor sound. Let's go over some of the most common causes of unclear vocals coming through a mic:
System not 'rung out' properly
When a sound system squeals, it means that either someone is pointing the microphone at a loudspeaker (which never works and can damage the speaker) or the sound system has not been tuned properly. Basically, the most efficient frequencies travel from the loudspeakers, back into the microphone and form a loop of sound we call feedback. Have you ever stood in between two parallel mirrors and saw and endless pattern of reflections? It's very similar to that.
When we turn up a sound system, certain frequencies start to ring before all others and we have to take these out before we can make the system any louder. We can achieve this with an equaliser (aka "EQ") that has multiple 'bands' for controlling individual regions within the sound spectrum. We simply take them out a little bit so they don't squeal, but this can only be done until the sound system will get as loud and clear as it gets - then we can't do it anymore.
Loud room
After we EQ the sound system properly within a room, we must now pay attention to the room. Even if it were possible to really CRANK the volume to incredible amounts, we would, at some point, only be increasing the volume of the room itself through the sound system.
This happens in rooms with loud HVAC systems or external noise problems (such as noisy service corridors or shipping areas right outside the room). When you start hearing the sound of the room, including audience sound, through the loudspeakers, it's time to investigate the possibility of briefing talkers on 'mic technique'.
Quiet talkers/singers
Assuming the sound system has been EQ'd ('tuned') and the room itself is not being amplified too much, the rest of the work is left to the talker or singer. Quiet talkers cannot be amplified without the risk of feedback (when going past the original tuning of the sound system or amplification of the room.
Quiet talkers can simply be reminded, before they speak, that they must speak up (or 'project') and stay within the useable range of the microphone (within 6 inches). They must be able to sense when they get too loud as well, by moving away from the microphone (unless a sound person is carefully monitoring them).
There's my three cents worth! Have a fantastic day!!
