<P> The use of acoustic foam and other absorbent means is less effective against this transmitted vibration . The user is advised to break the connection between the room that contains the noise source and the outside world . This is called acoustic decoupling . Ideal decoupling involves eliminating vibration transfer in both solid materials and in the air, so air - flow into the room is often controlled . This has safety implications: inside decoupled space, proper ventilation must be assured, and gas heaters cannot be used . </P> <P> Noise cancellation generators for active noise control are a relatively modern innovation . A microphone is used to pick up the sound that is then analyzed by a computer; then, sound waves with opposite polarity (180 ° phase at all frequencies) are output through a speaker, causing destructive interference and cancelling much of the noise . </P> <P> Residential soundproofing aims to decrease or eliminate the effects of exterior noise . The main focus of residential soundproofing in existing structures is the windows and doors . Solid wood doors are a better sound barrier than hollow doors . Curtains can be used to damp sound either through use of heavy materials or through the use of air chambers known as honeycombs . Single -, double - and triple - honeycomb designs achieve relatively greater degrees of sound damping . The primary soundproofing limit of curtains is the lack of a seal at the edge of the curtain, although this may be alleviated with the use of sealing features, such as hook and loop fastener, adhesive, magnets, or other materials . Thickness of glass will play a role when diagnosing sound leakage . Double - pane windows achieve somewhat greater sound damping than single - pane windows when well sealed into the opening of the window frame and wall . </P> <P> Significant noise reduction can also be achieved by installing a second interior window . In this case the exterior window remains in place while a slider or hung window is installed within the same wall openings . </P>

What kind of material can be used in the house to make it more soundproof
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