Problem – Sound bounces around the sanctuary / fellowship hall
The enemy of clear speech is reverb and “slap back”.
A room full of reverb is NOT good acoustics! It is to the musicians because it tends to blend notes together and smooth out the rough edges. That why tone def people like to sing in the shower.
Organist love lots of reverb. It makes an organ “fill the room”. And that’s fine. It does sound good. BUT . . . .
Excessive reverb destroys speech clarity. We’ve all been to gyms, convention centers, airports, and other large spaces, heard an announcement and had no clue what was said. Neither does your congregation or audience sitting in a room with sound bouncing all over the place.
Without getting into all of the technicals and math behind it, the best acoustic balance between too much reverb and too little for "most applications" is about 1.5 seconds. We want enough reverb to make music sound good so the room is not so “dead” but not so much that it makes designing a sound system for speech clarity difficult and expensive. The right speaker system designed includes reverb measurements taken on site or calculated from blueprints in the case of new construction. Yes – knowing the reverb time is that important. Reverb time alone can determine specific speaker system design elements.
Think of reverb in a room as fog. The more fog the more I have to design a speaker system to cut through that fog and focus sound into the seating areas. If you've ever seen a speaker system with what looks like huge funnels or horns pointed in all directions or line arrays, both are typically focusing sound in a very specific zone to avoid exciting room reverberation and putting in the listener in a direct sound field.
Another common problem is rear wall "slap back" or reflection.
Stand on the platform and clap your hands. See if you heard a reflection from the rear wall bounce back. In one church I consulted the rear wall reflection was so bad it was throwing the choir off. This is a very common and annoying problem.
Rear or any offending wall should be treated with acoustic absorption or reflection materials. You can either absorb the sound striking the back wall or change how it’s reflected. Most places use the familiar fabric covered sound panels. You can buy these prebuilt or make them yourself. You can also use interior design elements like banners, curtains, tilted walls, spaced vertical wood trimming, and other methods to break up the back wall or offending wall. The goal is to somehow stop the wall from acting like a mirror.
If you have a large amount of reflections or reverb in your space the
most immediate improvement you can make toward dramatically up grading
your sound is to fix these walls. You will be amazed at the difference
in the listening experience. The room just “feels” better.
copyright 2013 Cathedral Sound