Vibration Damping
I've discovered that my Home Theater has some vibration problems whenever the soundtrack has significant deep bass content and is played at a significant volume.  The problems start with peak levels around 90dB. 

There are two vibration conditions, the first is just general rumbling.  Any soundtrack or music program with significant bass information will, given a high enough sound pressure level (SPL) start rattling the suspended ceiling and light fixtures.

The second, and thankfully rare, condition is when the program contains sustained information at the room height resonant frequency, 71 Hz.  This just absolutely bounces the ceiling tiles and anything else that is not nailed down.

In order to counter these rather annoying conditions I've begun installing rolled, poly wrapped fiberglass insulation above the ceiling.  See the pictures above and below.

I've installed about 100 square feet of the stuff so far, mostly in the corners and at room boundaries where vibration is the worst.  It seems to work rather well; vibrations are gone where the insulation is installed. Quieting the worst vibrations has revealed other locations that vibrate, just not as loudly.

I intend to install this material over the rest of the ceiling and put some self adhesive duct insulation in some strategic locations on the vibrating light fixtures.

I'll update this page when the project is complete.  So far it looks like it will be a success.

Owens Corning Miraflex Attic Blanket, Poly Wrapped, R-25
Poly wrapped, rolled fiberglass insulation.  Ownens Corning Miraflex Brand.  About $12 USD per 25 foot (7.5 m) x 16 inch (37 cm) roll.
Fifth Element
Insulation in place above the suspended ceiling.

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Home Theater Room Frequency Response Info
Home Theater Room Frequency Response Info
Excel spreadsheet that shows resonant frequencies of my HT room and effects at listening position.  Spreadsheet template from Sterephile Guide to Home Theater Magazine.

For more technical info on acoustics and sound proofing check out this link.

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