Darwin and Christine reached their limit. Their church’s worship leader recently raised the band’s sound levels to the point that Darwin suffered ear pain and headaches.

The couple met with their pastors to request that volume levels be reduced to former levels. Instead of a lowering of decibels, the church offered the congregation free ear plugs to block the sound.

After 19 years of faithful membership in this church, Darwin and Christine reluctantly left. They’re looking for a new church where they feel they can participate in worship. It’s not the style of music that bothered them. They like contemporary worship music. It was the loudness that sent them out the door.

For this week’s Holy Soup podcast, I talked with Phil, the worship leader at that church. He defended the sound levels, which he said typically rise to 95 decibels (approximately the loudness of a jackhammer at 50 feet).

That’s loud. So loud that it hampers congregational singing. A new scientific study from Dr. David Gauger, music professor at Moody Bible Institute, found that such sound levels discourage congregational participation. “When you get above 90 decibels, it drops off dramatically,” Gauger said. “They do not feel they can worship. They cannot hear their own voice. They do not feel supported.”

Listen to my conversation with Gauger–and with Darwin and Christine and worship leader Phil–here on the Holy Soup podcast:

Gauger’s study determined that too-soft music also deterred congregational singing. When sound levels were kept below 70 decibels his subjects did not feel confident to sing along. The participants determined that the optimum sound level for singing was 81 decibels.

But many worship leaders today prefer to amplify the musicians much higher. I recently measured the levels at a large New York church. The sound regularly peaked above 100 decibels–in the middle of the room. I noticed few people were singing along. It was a loud concert atmosphere. What’s the goal here? Gauger said, “Concerts are great. But we can’t call it worship if we (the congregation) aren’t doing anything.”

So, why do musicians and sound technicians insist on elevating the sound levels beyond what many find bearable? They, like Phil, seem willing to lose people who can’t tolerate the noise. But, I’m curious, what are they afraid of if they’d reduce the volume just a bit? Do they fear that people would get up and bolt for the doors, screaming, “I can’t stand it in there! It’s not loud enough! Heck, my jackhammer is louder than that!”

When the surrounding sound is too loud–or too soft–worship participation suffers. “Singing in general is in decline,” Gauger said. “Nowadays we’ve relegated it to the professionals.”

If the goal is to put on a churchy spectator event, crank up the band–or the pipe organ–and don’t worry about the exodus of people like Darwin and Christine. But if the people’s participation is a priority, we now have some sound evidence to set reasonable audio levels.

When God’s people gather to worship, what should it sound like? Gauger concluded: “The real issue is, can the congregation hear itself?”

(Thom Schultz is the director of the film When God Left the Building.)