Re: Question regarding ISO 532 B and DIN 45 631 (Torben Poulsen )

Subject: Re: Question regarding ISO 532 B and DIN 45 631
From:    Torben Poulsen  <tp(at)DAT.DTU.DK>
Date:    Tue, 29 Aug 2000 12:25:30 +0200

Dear Aron and list As far as I know, the DIN standard has been revised in order to correct = for some low frequency 'errors' (< 100Hz). Ask Hugo Fastl, Munich, about = this. He was/is chairman of the DIN committee. The ISO standard has not = been revised accordingly. According to the definition, 1 sone is equal to 40 Phone (or dB SPL when = we talk about 1000 Hz) and a 10 phone increase will double the sone = value. This means that 70 dB SPL at 1000 Hz shall give 8 sone. The 7.4 = sone result may reflect the loudness difference between a pure tone and = a narrow band signal(?). Another explanation: The total loudness is = proportional to the area under the curve and thus the extra steps will = contribute marginally making 7.4 -> 8.0. The three stair steps - at the low frequency side - must be based on = measurements with actual filters and the stairs just reflects what's = coming through the two neighbour filters (800Hz and 630Hz) - where 1000 = Hz is way down at the skirts of the filters. In a calculation program = (with ideal filters?) there should be no input to the lower filters. If I specify 70 dB SPL at 1 kHz as input to (old) DOS programs I get the = following (all free field): DIN 45631 program: 6.94 sone, 68.0 phone Calculation program for B&K 2231 Sound level meter: 6.95 sone, 68.0 = phone Loudness model by Brian Moore (not DIN/ISO): 8.95 sone, 71.4 phone regards Torben -------------------------- Torben Poulsen Department of Acoustic Technology Technical University of Denmark DK-2800 Lyngby, Denmark Phone +45 4525 3940 (office), +45 4525 3930 (department) Fax +45 4588 0577 mobile +45 2326 0420 e-mail: tp(at) Web:

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