Hi

I believe you need to make your question a bit more specific as it may cover lots of aspects, e.g.

• Sound transmission
• Walking/foot fall  noise
• Acoustic absorption/damping

Sincerely

Claes

Hi Claes!

Thank you for your advice.

My interest in this subject is the Transmission Loss. Do you know anything about it?

Best regrads.

Hi Andressa

This is a well researched topic. You need to know the surface weight, the coincidence frequency and dampning to make a reasonable prediction for the speech range. For a slab in a building, I guess, the loss factor would be the major uncertainty.

I enclose a conference paper on the subject as some people have trouble with Google links.

The surface weight ('mass law') is just a version of Newtons 2nd law. The coincidence phenomenon is Snells law (which you find also in optics).

If you want to compute sound transmission at low frequency, you need to consider other approaches, modal analysis and/or FE as is done here

http://publications.lib.chalmers.se/records/fulltext/174785/174785.pdf

http://qringtech.com/2010/09/15/low-frequency-sound-transmission/

I see from your profile that your interest lies in lightweight concrete. I do not want to discourage you, but it might be useful to know that lightweight (stiff) concrete was used in Sweden in the 1960s - 1970s for high rise buildings but, was abandoned as it faced certain acoustic problems.

For what it is worth, as I have never worked the problem myself, one such problem is that a lightweight and stiff single wall of the same thickness get its coincidence frequency at a much lower frequency than does ordinary concrete. If you thin the lightweight concrete wall for equal bending stiffness, it will instead be lighter and transmit more sound. From what I have heard, there were also some problems with structure-borne sound where lightweight stiff concrete lead to high flanking transmission. Tor Kihlman researched the matter (see enclosed decription).

http://www.sciencedirect.com/science/article/pii/0003682X9390009U

(This one is in Swedish)

http://www.lth.se/fileadmin/byggnadsmaterial/BFR-publ/BFR_1963-15_reprint.pdf

http://www.worldscientific.com/doi/abs/10.1142/9789812838346_0006

Hope this helps

Claes

Hi Andressa, I suggest to take a look at the fundamental books "Structure Borne Sound" by Cremer et al.,  "Noise and Vibration Control" by Beranek and "Sound and Structural Vibration" by Fahy. In general terms you can find in these books all the basic (and detailed) information you need. I do hope it helps.

Hi, 

The attached publication refers primarily to the acoustic properties of crumb rubber concrete (CRC) however it covers the basic acoustic properties of standard concrete. It may be of some benefit to you if you are looking into lightweight concrete

Some notes that may help. 

          Damping is the phenomenon by which noise is ‘absorbed’ into a material. Materials such as cloth or foam have high absorption ratios (hence their use in cinemas/theatres) where as steel and concrete provide significantly less absorption. 

          Concrete can reflect upwards of 99% of sound energy as movement between concrete particles is minimal. This results in long reverberation times (echos) in sports halls and indoor industrial facilities.

          Transmission wrt frequency: Low frequency sounds have longer wavelengths which means they penetrate a larger surface area (therefore more transmission) than sounds of a higher frequency.  

For information regarding the science behind sound transmission look up a book called "Woods Guide to Noise Control". 

You should also look up the building regulations for the UK as they have minimum requirements for mass and density of materials being used between two rooms. As far as I know it is 415kg/m^2 for concrete (needs verification).

Regards,

Alex

Article Acoustic properties of concrete panels with crumb rubber as ...

Thanks for the tips Claes and also the suggested texts.

I will start reading immediately.

Thanks for the suggestions Alessandro!

I already have some of the books already and I started reading. I'm enjoying it a lot!