[Csnd] Absorption coefficients used by hrtfearly

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[Csnd] Absorption coefficients used by hrtfearly

gsenna
Hi,

Does anyone know what table of absorption coefficients was used for
creating the default values for the hrtfearly opcode?

I learned by looking at the source code that the default room materials
include things like:

walls: plasterboard

wall coef high = FL(0.3);
wall coef low = FL(0.1);
wall g1 = FL(0.75);
wall g2 = FL(0.95);
wall g3 = FL(0.9);

Now I'm trying to figure out how to match a table like this
(http://www.sengpielaudio.com/calculator-RT60Coeff.htm) with the
hrtfearly advanced input parameters. What frequencies in that table do
you think I should average to get the low and high coefficients?

Thanks in advance.

Cheers!

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Re: [Csnd] Absorption coefficients used by hrtfearly

Jeanette C.
Oct 4 2018, Guillermo Senna has written:

> Hi,
>
> Does anyone know what table of absorption coefficients was used for
> creating the default values for the hrtfearly opcode?
No, but you can work with the tables from Sengpielaudio or others. I
found a very extensive table on www.akustik.ua. It's a PDF with pages
and pages of coefficients.
...
> Now I'm trying to figure out how to match a table like this
> (http://www.sengpielaudio.com/calculator-RT60Coeff.htm) with the
> hrtfearly advanced input parameters. What frequencies in that table do
> you think I should average to get the low and high coefficients?
...
I just had the same problem, now solved. I used a simplistic view, but
the author of hrtfearly agreed that it would be a good starting point.
Use the 125Hz and 4000Hz coefficients for high and low and work with 1 -
coefficient for the gain values at 250Hz, 1000Hz and 4000Hz. It may take
some fine tuning, but it is a very good starting point for design.

HTH, best wishes,

Jeanette

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Re: [Csnd] Absorption coefficients used by hrtfearly

gsenna
Yes, I think that's exactly what I'll end up doing. Thanks!

Cheers.


On 04/10/18 07:12, Jeanette C. wrote:

> Oct 4 2018, Guillermo Senna has written:
>
>> Hi,
>>
>> Does anyone know what table of absorption coefficients was used for
>> creating the default values for the hrtfearly opcode?
> No, but you can work with the tables from Sengpielaudio or others. I
> found a very extensive table on www.akustik.ua. It's a PDF with pages
> and pages of coefficients.
> ...
>> Now I'm trying to figure out how to match a table like this
>> (http://www.sengpielaudio.com/calculator-RT60Coeff.htm) with the
>> hrtfearly advanced input parameters. What frequencies in that table do
>> you think I should average to get the low and high coefficients?
> ...
> I just had the same problem, now solved. I used a simplistic view, but
> the author of hrtfearly agreed that it would be a good starting point.
> Use the 125Hz and 4000Hz coefficients for high and low and work with 1 -
> coefficient for the gain values at 250Hz, 1000Hz and 4000Hz. It may take
> some fine tuning, but it is a very good starting point for design.
>
> HTH, best wishes,
>
> Jeanette
>

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Re: [Csnd] Absorption coefficients used by hrtfearly

Jeanette C.
Oct 5 2018, Guillermo Senna has written:

> Yes, I think that's exactly what I'll end up doing. Thanks!
In the sources to "in a room", you can take a look at big_room.ftable,
you will find all the hrtfearly parameters starting from wallhigh from
line 11.
Going from the absorption table at akustika.ua, I think I choose ceramic
tile walls and floor. Can't remember what I chose for the ceiling.
Ignore the last three values in that ftable. Just as a basis to compare
values "converted" and then tweaked to sound a little more natural.

HTH.

Jeanette

--
  * Website: http://juliencoder.de - for summer is a state of sound
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