If, by HATS you mean the Bruel and Kjaer 4128, you will find the diffuse field response in the following data sheet:
http://www.bksv.com/doc/Bp0521.pdf
For KEMAR, now made by Gras, there is considerable information in the handbook:
http://www.gras.dk/documents/00316.pdf
There was a fine comparison of diffuse-field measurements on various dummy heads in Acustica a few years back, but unfortunately I do not have the reference at hand.
Eric Benjamin
--- On Thu, 9/3/09, andre goldstein <goldstein.andre@xxxxxxxxx> wrote:
> From: andre goldstein <goldstein.andre@xxxxxxxxx>
> Subject: headphone equalization
> To: AUDITORY@xxxxxxxxxxxxxxx
> Date: Thursday, September 3, 2009, 8:51 AM
> Hello,
>
> I'm involved in some research about headphone
> equalization at a Unicamp university in Brazil and we are
> looking for the "diffuse field curve" and
> "free field curve" for HATS or KEMAR. I've
> done extensive search on the web but could not find it.
>
>
> Thanks in advance,
>
> Andre
>
>