By Aimee Sanford
How to ramp up sermon intelligibility and minimize background noise
Worship facilities are among the most common places you’ll see acoustical treatment. This is because the goal of a worship service is to spread the word and create fellowship. But, if the sermon is unintelligible, if musical detail is lost in reverberation, or if there’s distracting background noise, the congregation won’t be engaged — and might not even enjoy the service.
Consideration of the architectural acoustics in a sanctuary can ensure delivery of the message and result in delighted, inspired congregants who go out and encourage others to join them next time.
The key to addressing the acoustical problems in your sanctuary is to identify the noise issue and its source. Not all acoustical problems manifest from the same architectural component, and solutions differ in product material and placement.
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A challenging space
Church of Christ at Mountain View (CCMV) in Winchester, VA, had an issue with background noise, sound intensity and intelligibility. Tom Stephenson, a congregant and mechanical engineer who runs sound for the church, knew that one treatment wouldn’t solve all the acoustical issues.
After a recent remodel of the auditorium, the sanctuary’s newly painted block walls created a long RT60, or reverberation time — the number of seconds it takes for sound from a single source to “die,” or finish reverberating so that it can no longer be heard.
The longer the reverberation time, the less detail can be distinguished in sounds.
In addition, CCMV’s two projector rooms — located above either side of the stage — are cube-shaped, and open to the sanctuary seating area. The motor noise from the two projectors was reflected around the cubed-shaped enclosures, amplified, and then shot out the openings into the large worship hall. This made the projectors very audible to seated guests, creating a noticeable change in ambient noise when they were powered on and off.
“When we had programs or weddings in the auditorium and people wanted to show something on the projectors, we would have to keep them running throughout the service, even when we weren’t using them,” Stephenson explains. “If we turned them off, it would get suddenly silent in comparison, because you can hear the projector fans so loudly in the auditorium.”
Lastly, the cubic enclosures acted as amplifiers, not only for projector noise, but for any other sound that entered them. They reflected noise from the auditorium back out toward the audience as “slapback” echoes.
First, fabric-wrapped acoustical panels were installed along the lower level, the balcony facing, and the second level to absorb sound and decrease reverberation from audio, sermons and congregational chatter.
While this treatment increased intelligibility in the auditorium, it did not eliminate the distracting noise emitting form the projector rooms. To address this issue, treatment needed to be applied at the source. Environmentally friendly polyester acoustical panels were installed on the three walls inside each of the two large projection rooms, which prevented the buildup of motor noise before it even reached the congregation, and ended the persistent slapback echo.
“Response to the treatment has been great,” Stephenson says. “We can now hold all kinds of musical performances in here, and it sounds really good. I wouldn’t allow it before because I knew it would be a disaster.”
Also, the panels in the projection room have made it possible to power the projectors on and off during services with no sound change in the auditorium.
The reverberation time was decreased by more than a full second. And, Stephenson says he’s thrilled that some congregation members who used to use the church’s hearing assistance systems, no longer require them.
Aimee Sanford is communications specialist with Acoustical Solutions Inc., based in Richmond, VA.Feature photo: At Church of Christ at Mountain View (Winchester, VA), newly painted block walls created a long RT60, or reverberation time, resulting in less detailed sound quality. (Photo courtesy of Acoustical Solutions Inc.)