Worcester Chapter of the American Guild of Organists
founded 1949

Church sanctuary reverberation acoustics improvement through paint and pew cushions and carpet selection

First Unitarian, Worcester, improved sanctuary acoustics from about 1 second to 3 seconds during fire restoration by:

• Using a pew cushion insert liner, from Waggoners pew cushions
  The interior of the pew cushions contain 1 1/2" High Resilience foam with a sandwich both on top and bottom of a 1/4" "acoustic reflecive shell". The acoustic shell is glued to ensure it stays intact, and with it manufactured on both top and bottom the church can be assured that when they are flipped over (top to bottom side), they will always be acoustically live.
• Using an extra primer (sealer) coat of paint, and a final coat of [coming soon] paint which has the characteristics of [coming soon]
• Church sanctuary carpet:
  • Carpet salespeople will likely not know what you're talking about for pipe-organ-acoustic-friendly carpet, if anything it may be the opposite of what you want: recording studio absorptive carpet! (to deaden the sound)
  • Using as dense a pile as possible in the carpet, and still meet the aesthetic needs and foot-feel of the carpet committee
  • Choose a thread that is as reflective as possible
  • Minimize carpet usage, carpet area (use runners instead of wall-to-wall); if there's a battle to fight (trade-offs), it's better to eliminate carpet in the wide open areas, and let it stay (reluctantly) under the balconies or along the back wall
  • Eliminate padding (cushion) underneath-- directly glued is called direct jute; or minimize padding thickness

  We had no luck in eliminating some areas of carpets, and we had no luck in eliminating one area behind the pulpit which had curtains (another church had replaced their curtain backdrop with a beautiful wood lattice-like artwork "backdrop"- far better looking than dull curtains).
  Note that for special pipe organ recitals, we're considering putting plywood or masonite over an area of carpet that is the most acoustically critical.

Additional information, usually from people trying to sell you something, but may be os some value...

church-acoustics.com/faq-church-acoustics.htm

2004 AIO convention Notes: (excerpted from piporg-l)
Generally, the accepted material for walls and ceilings for new construction for optimum acoustics would be two layers of 3/4 inch sheetrock glued and screwed together. The framework for this would be typical studwall construction, but with the width between the studs randomized to avoid a resonance caused by all the studs being (say) 16 inches apart. Of course, stone, concrete or concrete block or even plaster of comparable thickness would probably be even better, but I am talking about minimum acceptable construction for very good acoustics with typical standard materials.
Sealers have been used to improve acoustics, notably in the case of Riverside Church, where porous stone was sealed to good effect. Sealing the pores in ceiling tile that is made of cushy wood fiber mounted on a not very rigid base frame is unlikely to do very much. As noted by other posts, the solution will be to replace the ceiling tile with a more rigid panleing of wood (I was surprised, though, that the URL about the Australian church told of using a 14.5mm (~0.5+ inch)veneered hardboard to replace the ceiling tile, rather than 1.5 inches of sheetrock) or sheetrock.