|
Microphones: Pulpits
Have you ever listened to a speech interrupted by feedback? Or worse yet, have you been the talker and encountered feedback? This article will explore some of the problems associated with the pulpit microphone and provide some hints to make yours work more effectively. 
Figure 1
One at a Time, please! Only one microphone should be placed on the pulpit at a time. Pretend you are the talker in Figure 1. Assume both microphones in the example are turned on. The top solid line in Figure 2 shows the combined frequency response of the two microphones assuming the talker remains exactly centered between the microphones. However, if the talker moves slightly off-center, the sound will travel a different distance to reach each microphone, arriving at slightly different times. When the two signals combine, there will be level additions at certain frequencies and cancellations at other frequencies. The result is unnatural sound. And worse yet, as the talker moves around, the sound quality will change too. The gold line in Figure 2 shows the resultant frequency response curve. 
Figure 2
The resultant change in frequency response is called phase cancellation. Phase cancellation can also occur when both a pulpit microphone and a lavaliere (neck) microphone are on at the same time. Recreate this situation for yourself: Turn on a pulpit microphone and a lavaliere microphone. Speak into both at the same time. You will quickly notice the combined result is very audible. The sound that is produced is very unnatural and the quality will change constantly as the talker moves. The tone controls on your mixer cannot correct this problem. The only solution is to turn off one of the microphones. You can also encounter a phase cancellation problem when one microphone is on a gooseneck above the pulpit. The sound from the talker travels from their mouth and strikes the microphone. However, some of the sound will continue to travel down, bounce off the pulpit and then travel back to the microphone. The path lengths are different, so there is time (phase) difference. The resultant combination again produces a sound that is unnatural. Pulpit Microphone Operational Hints Fortunately, there are several things you can do to improve this situation. -
Use a directional (cardioid) microphone. -
Put carpet or some other absorbent material in the pulpit to help absorb the sound reflection. -
Position the microphone at least 8 inches above the pulpit surface. -
If your pulpit is in the center of the platform, put the microphone in the center of the pulpit. If your pulpit is on one side of the platform, place the microphone so it is in the center of the talker's head rotation. -
Don't get too close to the microphone. -
Turn off all the microphones if they are not in use. 
Figure 3
What Microphone is Right for Me? Good question! Many new, exciting microphones are available today for pulpit applications. Many churches can use the new miniature microphones. They are mounted on a thin gooseneck that is easy to move. This makes it easy to adjust for the different heights of various talkers. These microphones also have a very small profile (Figure 3) so they look good. And best of all, they sound excellent! So don't be content with that old, big, ugly microphone any longer. Look into a new pulpit microphone today. by Ron Huisinga © 1996 Internet Sound Institute (www.soundinstitute.com). This article is for personal use only. Any commercial reproduction is not permitted without permission. To obtain permission, contact ISI at hopi@soundinstitute.com
< Back
|
