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Re: A problem about the relationship between perceived quality and loudness! thanks

This isn't surprising, really, and I wondered when it would come up. We have a similar experience when using large-number surround sound systems for investigating 'whole environment' perception. Because of the inherent system headroom involved in using <48 speakers with individual amps, it is common that people don't realise at all how loud it is until they try to talk over it - at which time they are startled to find they simply cannot be heard. The key here might also be that a single, very loud source produces one set of pinnae cues, complete with narrow notches and boosts of HF. Most approaches to large-scale spatial sound use multiple drivers - in separate locations, naturally, to attempt 'wavefield reconstruction' - as these attempts become less precise with increasing frequency, the pinnae cues are homogenised - removing the peaks and troughs. This has a fortunate byproduct of minimising hearing damage due to high levels - the familiar HF 'notch' in hearing that many sound engineers and musicians (especially violinists?) suffer from - but it also colours judgements of just how loud the system is.

Dr Peter Lennox
Director of Signal Processing and Applications Research Group (SPARG)
School of Technology,
Faculty of Arts, design and Technology
University of Derby, UK
e: p.lennox@xxxxxxxxxxx
t: 01332 593155
w: http://sparg.derby.ac.uk/SPARG/Staff_PLX.asp
From: AUDITORY - Research in Auditory Perception [AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Brett Crockett [BGC@xxxxxxxxx]
Sent: 08 July 2008 19:53
To: Peter Lennox; AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: A problem about the relationship between perceived quality and loudness! thanks

Sony's Inflator product actually introduces even harmonics (like a tube
amp) to make music sound louder.

-----Original Message-----
From: AUDITORY - Research in Auditory Perception
[mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Bob Masta
Sent: Friday, July 04, 2008 5:21 AM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: 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
Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!

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