Impact of sound insulation on kids bedroom above cinema room


Standard Member
Ok, so I finally got round to repeating my SPL testing in the kids bedrooms following my DIY cinema room build including sound insulation measures.
I couldn't get the exact same volume in the cinema room (slightly lower. I assume due to the sound absorption and furniture).
But I compared the differences between the SPL in the cinema and the SPL in kids bedroom with the music at same volume.
Before build:
With in-room SPL reading LCSMax of 90.9 dB.
I got 70.1 in Bedroom 1 (directly above), giving 20.8 delta.
55.5 in Bedroom 2, giving 35.4 delta.

After build:
With in-room SPL reading LCSMax of 86.9 dB.
I got 63 in Bedroom 1 (directly above), giving 23.9 delta.
47.2 in Bedroom 2, giving 39.7 delta.

Comparing Before vs After build:
-3.1 dB impact in Thea's room.
-4.3 dB impact in Zander's room. It doesn't sound a big number, but if I remember correctly 3 dB is half the power.

So I'm pretty happy with the result.
In practice, I can be listening to music/movies at a good volume and barely hear it in the room directly above.

My testing approach:
  • I used the same Sonos One (as didn't have an operational HiFi pre-build), set to 95% volume and placed in the same location in the cinema room.
  • Used REW's SPL Level Logger to record the same 90 sec clip of Latch feat. Sam Smith.

Sound insulation:
My main objective was to create a space for the new cabling, but also wanted a balanced approach to sound insulation as the kids bedrooms are directly above and I want to be able to listen/watch at good levels.

Ceiling Measures:
  • Genie Clips with metal furring bars.
  • Double layer of 12.5mm standard plasterboard, silicon sealant applied in between.
  • Cavities filled with Rockwool Acoustic Slabs.
  • New Plasterboard had 5mm gap around the perimeter, which was then filled with silicon sealant.
Hope that helps.


Standard Member
Did you use silicone or acoustic sealant?
Standard silicone sealant.
Having looked into and balanced the cost (acoustic sealant is 10x), I understood the main objective to be making joints air tight whilst maintaining mechanical decoupling - so needs something flexible.

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