
knightfly
GrouchyOldFartOnBatteries
"3. do you need a floating drum riser on a cement basement floor, what's the purpose exactly? I don't think there's much acoustic coupling going on with a cement floor." -
Here's a 288 page document on flanking that will explain this better than I could -
http://irc.nrc-cnrc.gc.ca/irc/fulltext/rr103/rr103.pdf
If you don't want to read 288 pages, here's an excerpt -
Figure 2-2 shows that the power transmitted from the source room to the receiver
room is determined by five factors in the transmission path:
1. Efficiency of power injection into the flanking surface by an airborne or impact
source,
2. Power attenuation from the point of power injection to the junction connecting
the flanking elements,
3. Power attenuation through the junction,
4. Power attenuation between the junction and the point at which radiation
occurs,
5. Efficiency of conversion from structure borne power to airborne power in the
receiver room.
#1 is the main reason for floating drum risers with well-damped, heavy floated floors.
The other 4 points are also important, and are usually NOT optimised in normal house construction because few contractors even KNOW about this, and even fewer will actually DO anything about it, because it costs more to build when you have to break flanking paths.
HTH... Steve
Here's a 288 page document on flanking that will explain this better than I could -
http://irc.nrc-cnrc.gc.ca/irc/fulltext/rr103/rr103.pdf
If you don't want to read 288 pages, here's an excerpt -
Figure 2-2 shows that the power transmitted from the source room to the receiver
room is determined by five factors in the transmission path:
1. Efficiency of power injection into the flanking surface by an airborne or impact
source,
2. Power attenuation from the point of power injection to the junction connecting
the flanking elements,
3. Power attenuation through the junction,
4. Power attenuation between the junction and the point at which radiation
occurs,
5. Efficiency of conversion from structure borne power to airborne power in the
receiver room.
#1 is the main reason for floating drum risers with well-damped, heavy floated floors.
The other 4 points are also important, and are usually NOT optimised in normal house construction because few contractors even KNOW about this, and even fewer will actually DO anything about it, because it costs more to build when you have to break flanking paths.
HTH... Steve