아래층에서 화장실 천장을 열고 화장실 문과 가까운 천장 시멘트에 25w 출력의 진동스피커를...

I’m suggesting practical methods without needing construction:

• Add mass with a thick rug and dense felt pad outside the bathroom door.
• Seal the gap with a door sweep or draft stopper.
• Consider weatherstripping and acoustic panels.
• Use white noise for extra sound masking.

For the rug, a typical size would be 1.6 x 2.3 m, with a high-pile rug and 6 mm pad, offering around 5–8 dB reduction in airborne noise. For footstep noise, the reduction could be higher, but measurements vary.

For matching decibel reduction, research suggests that a 6 mm underlay with 25% absorption adds about 4 dB. Comparing carpet to bare floors, the NRC differences (0.35 for carpet vs 0.02 for floors) result in a 5-10 dB reduction. I’ll recommend rug sizes based on a typical Finnish bathroom door (70-80 cm), proposing coverage 1 m larger on each side for optimal effect. Budget options include IKEA’s LINDKNUD, while the premium choice adds felt pads. I’ll calculate approximate dB reductions per setup as well.

Thought for 1m 37s