Then there was Mother Nature's "wood fiberboard" and "hemp" or "hemp acoustic panels" & HempFlax Thermo Hemp Premium Plus, then corrugated cardboard with quartz sand "Wolf Bavaria sound insulation panel PhoneStar TWIN"!

 

Per data given here - hemp wool is a preferred material for making a bass trap, because of its lower flow resistivity compared to other insulation wool.

The sad thing is that basically none of manufacturers specifies flow r. or density of their products. Although one old sound engineer from Gearslutz (I think it was Brandt) said that the correlation between these parameters and sound qualities still remains unproven, because there are too many variables...

 

You can sometimes find two values in data sheets. One is the flow resistance specifically related to this material thickness (for example 5cm). It has the unit Pa*s/m. Since every manufacturer has different thicknesses in its range and we first want to determine which thickness is actually suitable for us, this value alone does not help us.

The second value is the length-specific flow resistance, where the previous value is divided by the material thickness. It is therefore purely dependent on the material and no longer on the thickness used for the measurement. It can be identified by the unit Pa*s/m2.

With common sense you can already guess that there is a connection between the density, i.e. the specific weight of the material, and the flow resistance. To get an overview of the ranges in which this value moves, I worked through some common mineral wool products and wrote down the flow resistance and density for each one.

Source: https://www.jochenschulz.me/de/blog/steinwolle-glaswolle-hanf-absorber-material

 

Why not use dry Tree Leaves?

"Sugar maple (Acer saccharum) waste leaves as a renewable resource for sound absorption"
https://www.sciencedirect.com/science/article/abs/pii/S2213343723024041

"Effects of Air-Dried Leaves of Evergreen Broad-Leaved Trees on Sound Absorption Property"
https://www.woodj.org/archive/view_article?pid=wood-49-5-482

"Sound Absorption Property of the Leaves of Two Evergreen Broad-Leaved Tree Species"
https://www.woodj.org/archive/view_article?pid=wood-48-5-631

"Acoustical properties of living plants"
https://www.researchgate.net/publication/287309158_Acoustical_properties_of_living_plants

"Sound absorption by tree bark"
https://discovery.ucl.ac.uk/id/eprint/10119763/1/000543.pdf

 

HempFlax Thermo Hemp Premium Plus 1200 x 580 mm 30 - 140 mm
Source: www.naturanum.de/thermo-natur-hanf-premium-mattenware

Sound insulation Length-related flow resistance (tested according to EN 29053:1993) 3.0 kPa•s/m2
The sound absorption data in English can be found in the attached picture.

 

The bed mattress behind me performed better than any acoustical material I installed.

 

i believe hemp is not better than wool in terms of humidity resistance. it just smells better when it decomposes.

sure, those who can, go for something natural. in my rooms it is quite cold in winter so i am a bit biased with this kind of stuff.

and also do not forget that all of this burns like hell. basotect will not.

 

Get smart and get rid of prejudices or false knowledge. https://www.steico.com/en/ the example board is called Steico flex WLS 038 wood fiber insulation, in front of it there are 2 layers of Regibst cardboard and you have it warm and it's quiet and the room climate is also biologically healthy.

Sound can be dampened with

- Airtight connections
- Heavy materials to dampen low frequencies
- Sound traps in porous materials to catch high frequencies.

More wood fiber behind plaster is of little or no use. On one side, around 30 mm is the efficiency limit. With 80 mm, you get more than 2* 30mm
More plaster or, as suggested, a projecting plaster with a trap behind it is far more effective.
Connections, connections, connections!
To dampen low frequencies, a solid wood door is of course an advantage.
Overflow boxes with silencers dampen better than door gaps.
Knauf has a sound insulation calculator and has instructions on how to design connections with telescopes, for example, to ensure tightness.