Re: Image-source model with consideration of air absorption

[Junfeng Li <junfeng@xxxxxxxxxxx>]

Dear Emmanuel,

>From the code, the transfer function (green function) has been changed from (exp(jwd)/d) to (exp(jwd)*m/d) where m is the attenuation factor when air absorption is considered. Also, the equation used for calculating "m" is only valid under 10 kHz. But what it should be for higher frequencies (e.g., fs = 48 kHz)?

However, I am not sure this calculation. Therefore, I need some books/paper to confirm it.

Best regards,
Junfeng 



On 11/11/22, Emmanuel Vincent  <emmanuel.vincent@xxxxxxxx> wrote:

> The URL http://www.irisa.fr/metiss/members/evincent/Roomsimove.zip is correct.
> 
> I don't know about the Green function but you can read it from the code.
> 
> Emmanuel
> 
> 
> On 11/22/2011 11:57 AM, Junfeng Li wrote:
> >Dear Emmanuel,
> >
> >Thanks a lot for your information.
> >I found that Roomsim (http://media.uws.ac.uk/~campbell/Roomsim/) implemented this function. your Roomsimove cannot be found from the URL that you provided below. Could you check it again?
> >
> >My another concern is what the Green function ï exp(jwd/(4*pi*d) ï in the free field should be when it is extended when considering the air absorption effect?
> >
> >Do you have any idea? or references on this issue?
> >ïThough I believe it is a very easy question, I cannot find the answer, ....)
> >
> >Thanks a lot again.
> >
> >Cheers,
> >
> >Junfeng
> >
> >
> >
> >On 11/11/22, Emmanuel Vincent<emmanuel.vincent@xxxxxxxx>Â wrote:
> >
> >>Dear Junfeng,
> >>
> >>Roomsim (http://media.uws.ac.uk/~campbell/Roomsim/) as well as our command-line software Roomsimove (for moving sources)(http://www.irisa.fr/metiss/members/evincent/Roomsimove.zip) account for this.
> >>
> >>Emmanuel
> >>
> >>--
> >>Emmanuel Vincent
> >>METISS Project-Team
> >>INRIA Rennes - Bretagne Atlantique
> >>Campus de Beaulieu, 35042 Rennes cedex, France
> >>Phone: +332 9984 2269 - Fax: +332 9984 7171
> >>Web: http://www.irisa.fr/metiss/members/evincent/
> >>
> >>
> >>On 11/22/2011 11:28 AM, Junfeng Li wrote:
> >>>Dear list,
> >>>
> >>>I am now considering to generate room impulse response (RIR) using the well-known image-source method. However, I found that the traditional image-source method only considered the absorption of enclosure surfaces, without the consideration of air absorption. However, the air absorption should be also an important factor which affect the simulated RIR.
> >>>
> >>>To reformulate the image-source method, the Green function ï exp(jwd/(4*pi*d) ï in the free field should be extended to that with the consideration of air absorption effect. I searched this problem for some days. However, I did not find any reference.
> >>>
> >>>Could anyone point some references on this issue or the (source code of) improved image-source method that implemented this idea?
> >>>
> >>>Thank you so much in advance.
> >>>
> >>>Best regards,
> >>>Junfeng
> >
> 
> 
> -- 
> Emmanuel Vincent
> METISS Project-Team
> INRIA Rennes - Bretagne Atlantique
> Campus de Beaulieu, 35042 Rennes cedex, France
> Phone: +332 9984 2269 - Fax: +332 9984 7171
> Web: http://www.irisa.fr/metiss/members/evincent/