> the second part of that response is just patronising and rude <
That was not the intent. But I already explained it six ways to Sunday. If he can't - or won't - understand, that's not my fault. This is not a complicated concept!
As for rudeness, I noticed that yet again you had to edit someone else's post repeatedly. So why single me out rather than that other person?
> as Eric had already explained and has again, the absorption, transmission and reflection properties of a window are related. Yes, they all describe different parts of the mechanical behaviour of the window but they are all physically related. <
No disagreement there. I came to the realization on my own years ago that all materials pass, absorb, and reflect, all at the same time.
We can argue about this forever, but until someone posts some hard data to show how much less a window reflects than a sheet rock wall, this will continue indefinitely. I'd have thought that Eric would have such data handy. I found some graphs that were close, but not exact, in about five minutes on Google.
It should be obvious, intuitively, to all that a window reflects bass frequencies less than a solid wall. How much less I can't say for sure because I never measured that. But I did already make the point that reducing a reflection even a little reduces the severity of the resulting acoustic null by a much larger amount. Even a 1 dB reduction in the strength of a reflection reduces the depth of a null by many dB.
Since nobody else is offering any data I'll go first. Here are some hard numbers on the relative significance of a reflection:
- If a reflection is 100 percent it will create a null of infinite depth 1/4 wavelength away from the boundary.
If you reduce the reflection by 1 dB the null is now only 19 dB deep.
Reduce it another dB and now the null is only 14 dB deep.
Reduce it again to -3 dB and now the null is only 11 dB deep.
If you reduce it to -6 dB the null is now only 6 dB deep.
So if glass reflects, say, 40 Hz at -6 dB compared to -1 dB for sheet rock, that alone accounts for a huge improvement in the LF response inside the room. Depending on how much of the entire wall is glass, of course.