Question regarding ISO 532 B and DIN 45 631 (Aaron Hastings )

Subject: Question regarding ISO 532 B and DIN 45 631
From:    Aaron Hastings  <alh1138(at)HOTMAIL.COM>
Date:    Mon, 28 Aug 2000 21:40:56 -0500

I have been looking at these two standards. I have three programs which calculate loudness; one, I wrote in matlab based on a BASIC program submitted to Acustica, Vol. 55 (1984), one, a matlab program another member of the group was kind enough to send me, and one I found on the internet. Both matlab programs plot the specific loudness as well as giving total loudness. My problem is this, there is an example on the second to last page of DIN 45 631 which deals with a 1000 Hz pure tone with a level of 70 dB. In the DIN standard, it gives a total loudness of 8.02 sones. The shape of the contour is three stair steps (from left to right) then a smooth slope. All three programs that I have tried for this have given a level of 7.4 sones (for free field). Further, the two matlab programs have only one stair step and then a slope. It seems like all three programs are not getting the accessory excitation for the lower frequencies correct. As far as I know all three programs were written independently although they may all (mine at least is) be based on the Acustica, Vol. 55 (1984) article. Question: Does anyone know if there was something wrong with the Acustica, Vol. 55 (1984) program? Question: Does anyone have any comments / suggestions? Thanks Aaron

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