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Lars


Rene Dalmeijer rened@... wrote:
> Andre,
> 
> I suppose you also read John Glassfords mail with ale in
> hand and decibel 
> meter in other. Although his measuremnts seem crude he did
> very well by 
> taking note of ambient sound levels. I expect a reasonably
> executed SB wall 
> without acoustic defects like the ones described by Andre
> will perform in 
> the region of 60dB and upwards.
> 
> The fact that SB walls are a poor sound insulator is a
> vicious rumor. I 
> presume that Arnoud Cauwel is a promoter of pisee and other
> earth 
> techniques. Heavy mass like a meter of concrete are
> necessary for very low 
> frequencies ie <60 Hz above this most simple building
> structures, even 
> quite light ones, can dampen sound quite effectively if
> executed properly. 
> It is even possible to reach -60dB damping with a few not
> too thick panes 
> of glass (like in sound studios).
> 
> Besides mass stiffness and de-coupling are very important
> for acoustic 
> sound insulation. The relatively low stiffness of a SB wall
> with earthen 
> plaster are ideal. The fact that the cavity between the two
> outer stucco 
> shells is filled with straw is excellent acoustic damping.
> Beware to be 
> careful and fill all cavities and voids with straw clay,
> avoid any direct 
> mechanical contacts between inner and outer shells, these
> will seriously 
> degrade sound damping performance. Contrary to what you
> would expect 
> loosely packed bales will perform better then very tightly
> packed (rice is 
> ideal). Pay a lot of attention to all openings and edges
> these are the weak 
> points. An air leak of only a 1mm^2 will seriously degrade
> performance. 
> Door openings and windows are literally acoustic holes in
> the wall these 
> need special detailing and attention to even remotely
> approach the 
> performance of the walls. Doors even double ones have a poor
> performance. 
> The gaskets and seals in the doors should be double or even
> triple but even 
> then there is the problem that over time the seals will
> degrade and leaks 
> will occur. The type of doors you are aiming for is more
> like a steel 
> watertight door in a ship then a house door with multiple
> closing bolts and 
> tightening clamps.
> 
> In conclusion I would like to add due to the nature of a SB
> wall (homogenic 
> continuous surface) the wall is not the problem but the
> connections between 
> the wall and all other structures incorporated or
> surrounding it. I 
> strongly suspect that most sound insulation tests executed
> on SB walls are 
> measuring the defects of other structural components or
> mistakes in the 
> test procedure (a non calibrated sound source, Background
> noise etc.)
> 
> Andre regarding room acoustics. Here are some simple rules
> of thumb 
> depending on the type of acoustics you want ie very lively
> to very well 
> damped. Soft acoustic instruments require a live room. Loud
> amplified sound 
> a dead room. The single most important parameter is the
> reverberation time 
> and level. The harder the surfaces the livelier the sound. A
> bathroom is 
> lively hence your drive to sing even if you can't. The
> opposite is standing 
> on top of snow bound hillock. The bigger and harder the room
> the longer the 
> reverberation time ie a cathedral. Next the relative
> dimensions. An oblong 
> box (like Concertgebouw Amsterdam) approaches the ideal.
> Preferably the 
> dimensions relate to each other approximately in the
> following manner 2-3-5 
> (I don't have the exact figures at hand at the moment but
> this ratio will 
> avoid predominant harmonic resonances and standing waves)
> the exact ratios 
> depend on the size and acoustic reflectiveness. I personally
> prefer rooms 
> without parallel surfaces thus avoiding standing waves. I
> think if you 
> build a room with clay stucco and wooden flooring and a well
> pitched 
> ceiling you will have quite acceptable acoustics for
> acoustic performances. 
> If its too live you can always add some damping afterwards
> 
> 
> At 10:47 AM 10/16/02, you wrote:
> >Hi,
> >
> >In France there is a vicous rumour going arround that SB
> walls are a poor
> >sound insulator. Arnaud Cauwel wrote a report for his
> school of architecture
> >in which he claimed that straw (because of its low mass)
> insulates poorly.
> >No numbers or test data is given.
> >
> >Lars informed me on the Danish sound test some while ago,
> and specifficly
> >stated that I cannot quote him since the info is not
> official yet.
> >However I think it is safe to say that the result of the
> test was probably
> >greatly influenced by the post and beam structure and that
> the results were
> >not very impressive (for as far as I can understand them
> :-) 'cause the
> >universe of sound is complex thing. I feel that a beam (to
> carry the floor
> >for instance) that goes through the inside plaster and sits
> on the ring beam
> >would probably give a great transmission of sound to the
> outside plaster
> >just next to the ring beam, circumventing the 90% of the SB
> wall.
> >
> >And than there is the question of indoor accoustics.
> Friends of us want to
> >build a SB Art & concert hall, so they are also concerned
> about how the
> >sound will be for the audience and what we can do to
> enhance that quality
> >with the shape and surface of the walls.  Any hints?
> >
> >Bye
> >Andre
> >www.la-maison-en-paille.com
> >
> >
> >----- Original Message -----
> >From: Rene Dalmeijer rened@...
> >To: GSBN GSBN@...
> >Cc: J.J.de.Groot@...; Rob Kaptein
> ramstrobouw@...
> >Sent: Tuesday, October 15, 2002 11:01 PM
> >Subject: Re: GSBN:Re: STC of Straw bales
> >
> >
> > > Bruce, Tom
> > >
> > > There is a chance that we will be doing a test here
> regarding the SB
> > > acoustic insulation value. The test if executed will be
> in a test
> >facillity
> > > at the Eindhoven University normally used to test window
> frames so I
> >expect
> > > that the measured values will till how well the test
> facilty functions. I
> > > am sure that a properly executed SB wall has excellent
> sound insulation
> > > properties far exceeding normal brick walls. What are
> STC numbers? We
> >don't
> > > use this qualification here. BTW the test will
> incorporate a spectral
> > > distribution.
> > >
> > > At 12:22 AM 10/15/02, you wrote:
> > > > > I recall there was some discussion of SB sound
> transmission on the
> > > > > list some time ago, including anecdotal evidence
> provided by the
> > > > > Straw Wolf's rock band or some such.  Anyone have
> any solid numbers
> > > > > for Katie?  Failing that, anyone have any good
> stories to tell? ;-)
> > > >
> > > >
> > > >To my knowledge, no formal tests have been done to
> provide STC numbers at
> > > >various sound frequency levels (such as building
> engineers sometimes
> >need).
> > > >We all know they're mighty quiet, and that it's hard to
> shout through a
> >wall
> > > >to someone on the other side, but don't have the exact
> geek numbers as
> >yet.
> > > >
> > > >Or, if someone does, I would very much appreciate
> learning of it, as the
> > > >culmination of the EBNet test program aims to be a
> compilation of ALL
> > > >testing of ALL sorts done to date - by EBNet or by
> others.
> > >
> > > Greetings,
> > >
> > > Rene Dalmeijer
> > >
> > > ----
> > > For instructions on joining, leaving, or otherwise using
> the GSBN list,
> >send email to GSBN@...HELP in the
> SUBJECT line.
> > > ----
> > >
> >
> >
> >----
> >For instructions on joining, leaving, or otherwise using
> the GSBN list, 
> >send email to GSBN@...HELP in the
> SUBJECT line.
> >----
> 
> Greetings,
> 
> Rene Dalmeijer
> 
> ----
> For instructions on joining, leaving, or otherwise using the
> GSBN list, send email to GSBN@...
> HELP in the SUBJECT line.  
> ----
> 


~~~

Lars Keller
Friland 12 B
Feldballe
8410 Ronde
Danmark

0045-20240505
larskeller@...
~~~


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