From: "Noral Stewart" 
Newsgroups: misc.consumers.house alt.home.repair alt.sci.physics.acoustics
Subject: Re: Reducing Noise/Vibration from Trucks
Date: Fri, 30 Jan 2004 10:49:37 GMT


"Tony"  wrote in message
news:pT8Sb.666$Ss3.6625426@news-text.cableinet.net...
> "SQLit"  wrote in message
> news:mKXRb.22845$F15.10184@fed1read06...
> >
> > If your stuck with 8' walls then why not try a hedge, Greenery absorbs
> sound
> > and cuts the dust. I an not aware of any laws about planting shrubs on
> their
> > height.
>
> Evidence seems to show that usually the only significant improvement from
a
> hedge is psychological - which is not to say it is a bad idea.
>
> Secondary glazing can work well so long as the windows are shut (!), the
> walls are fairly heavy, and there are no other significant leaks.   Make
> sure the outer windows are really well sealed (you may want a very small
> deliberate leak to reduce condensation) and make the air gap between the
two
> panes as large as possible.  If the air gap cannot be large you could use
> heavier glass (6 - 10 mm).  Avoid thermal double glazed units which are
> worse at low frequencies than solid glass of the same weight.
>
> Whether the wall will work depends on the geometry of the site.  If it
gives
> visual shielding it will work to some extent at least, but watch out for
> sound coming round the ends.  You may not need masonry, you will get some
> effect from a heavy timber wall with no gaps.  Since some sound will get
> round the wall, the higher performance of the masonry may not be
> significant.
> The extra sound reflected to the opposite side of the road may be
detectable
> but will probably not be very significant unless your wall is quite close
to
> the traffic.  You may have to be careful if there is a barrier on the
other
> side, you should make sure your wall does not reflect sound over the
barrier
> to windows that would otherwise be shielded.   You can work it out with
> angle of incidence = angle of reflection.
>
> Tony Woolf
>
>
Tony,
That is such an excellent concise set of comments that I just had to say so.
A couple of comments I would add.  While a small deliberate leak can be
considered for condensation control, make sure the other window that does
not have the leak is well sealed.  Also, it can be helpful to use laminated
safety glass for the added window.

Noral Stewart