Subject: Re: A problem about the relationship between perceived quality and loudness! thanks From: Bob Masta <audio@xxxxxxxx> Date: Mon, 7 Jul 2008 08:25:29 -0400 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>
Junyong: After much searching through my old files, I have found what I think to be the original report... but it is disappointing in that it is not quite what I remembered, and hardly a suitable scientific reference. It is a reprint from "Hi-FI for Pleasure" magazine (UK?) from the Dec 1975 and Mar 1976 issues entitled "17 Amplifiers Taken to Task". Unlike most such tests, this was conducted double-blind and seems to have been quite rigorously controlled. Each amplifier was evaluated (blind) by a panel of listeners, who were asked (among many other things) to set the "maximum tolerable loudness" subjectively, and the objective SPL was measured and recorded for each amplifier tested. The loudness setting was presumably a consensus among the panel. The article presents all these SPL values (along with the usual technical specifications and subjective evaluations) for each unit tested. The overall conclusions stated: "An interesting side effect was noted in conjunction with the high power testing. Some amplifiers did not sound 'loud' in the annoying sense and yet produced high sound levels as measured on the sound level meter. Conversely, others sounded loud even at lower measured levels. This altter effect was considered a bad sign in terms of amplifier quality." Sorry if I raised any false hopes! Best regards, Bob Masta ---------------------------------- On 5 Jul 2008 at 18:55, Junyong You wrote: > Hi Bob, > > Thank you very much for the information. In fact, I am doing the objective audio quality metric, e.g. PEAQ, and I want to take into account the loudness. So originally, I hope to get an experiential curve of the percieved quality with respect to loudness, that means, once I get a PEAQ value for one audio segment, perhaps another weight can be utilized to adjust such value. I guess it maybe hard to get this weight, even not very accurate. In my guess, the ideal curve maybe like following, but I don't have any proof. > > > However, according to your information, the above curve should not be accurate. Could you please give me more information about the study in 1970 you mentioned? Thank you very much. > > Best Regards, > Sincerely, > Junyong You (Ph. D) > > Senior Researcher, > Department of Signal Processing, > Tampere University of Technology, > Nokia Research Center, > Tampere, Finland. > E-mail: junyong.you@xxxxxxxx > > > ----- Original Message ----- > From: "Bob Masta" <audio@xxxxxxxx> > To: <AUDITORY@xxxxxxxx> > Sent: Friday, July 04, 2008 3:20 PM > Subject: Re: [AUDITORY] A problem about the relationship between perceived quality and loudness! thanks > > > > Perhaps not exactly what you asked about, but many years > > ago (1970s?) there was a study where subjects were asked to > > adjust the volume of various audio systems until they were > > "loud". The surprising result was that high-powered > > systems were turned up to much higher output levels than > > low-powered systems before they were "loud". The > > explanation given was that subjects apparently correlated > > increased distortion (more than actual SPL) with "loud". > > > > Since amp distortion shoots up as the amp begins to clip at > > its maximum output level, the low-powered amps of course > > began to distort while producing lower SPL than the high- > > powered amps. > > > > > > Best regards, > > > > Bob Masta > > > > > > ----------------------------------- > > On 3 Jul 2008 at 18:20, Junyong You wrote: > > > >> Hi All, > >> > >> As we know, loudness is an important audio index for human perception. Is > >> there anyone studied the relationship between quality distortion and the > >> loudness? I mean, if the same objective distortion happened on the different > >> audios (or segments) with different loudness, then, is there some difference > >> between the perceived qualities of these two audios (or segments)? > >> > >> I guess the loudness should influence the perceived quality of same > >> distortion, and for the very low and very high loudness, such influence > >> maybe not very great, but with ordinary loudness, perhaps the perceived > >> distortion will increase following the loudness. > >> > >> This is just my guess, anybody can help to work for it with me? Or could you > >> please give me some advice and references? > >> > >> Thank you very much, any feedback will be greatly appreciated. > >> > >> Best Regards, > >> > >> Junyong > > > > Bob Masta > > > > D A Q A R T A > > Data AcQuisition And Real-Time Analysis > > www.daqarta.com > > Scope, Spectrum, Spectrogram, Signal Generator > > Science with your sound card! > > Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis www.daqarta.com Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!