Prev: Calc freqs of triple tuned bandpass filters?
Next: generating a coherent signal
From: snickell on 28 May 2010 14:45
Hi Andrew,

I was imprecise in my post, I'm using an equal loudness contour from
ISO226:2003 instead of A-Weighting.... though in some ways that may be
worse (measured for pure tones instead of wide spectrum noise). I
think I'll switch to ITU 1770. It makes more sense for my application
(signals are mostly music and speech).

That hydrogenaudio discussion is spot on, thanks.

I found the AES paper by Skovenborg ( http://www.tcelectronic.com/media/skovenborg_2004_loudness_m.pdf
) particularly interesting. Also ReplayGain is interesting just
because it is so widely used (and uses the simplistic system I just
proposed with the addition of a statistical measure.... rather than
the mean of all RMS measurements, they take the 5%-from-top value as
representative).

One conclusion I drew from the Skovenborg paper is relatively
simplistic frequency-weighted-intensity measures, while not as good as
other measures, are 'pretty good' in return for a much simpler
implementation. That answers my overall question.

-Seth

On May 27, 6:08 pm, Andrew Reilly <areilly...(a)bigpond.net.au> wrote:
> On Thu, 27 May 2010 12:04:04 -0700, snickell wrote:
>
> [a-weighting RMS power to make equal loudness]
>
> > Is there a better one?
>
> Officially, ITU-R BS.1770 is supposed to be a better measure of loudness
> than A-weighting.
>
> There are some links to useful papers in this discussion:http://www.hydrogenaudio.org/forums/lofiversion/index.php/t47154.html
>
> Cheers,
>
> --
> Andrew

From: snickell on 28 May 2010 14:49
The 'perceptual element' you discuss is close to what I want to
measure. In order to measure it, I want to eliminate the bias toward
loud signals ('oh wow, that amplifier is so detailed, so precise' ....
'sorry, its just set to higher gain than the other one, thank you,
please play again').

-Seth

On May 27, 7:56 pm, "steveu" <steveu(a)n_o_s_p_a_m.coppice.org> wrote:
> >Andrew Reilly <areilly...(a)bigpond.net.au> wrote:
> >> On Thu, 27 May 2010 12:04:04 -0700, snickell wrote:
> >> [a-weighting RMS power to make equal loudness]
> >>> Is there a better one?
>
> >> Officially, ITU-R BS.1770 is supposed to be a better measure of loudness
> >> than A-weighting.
>
> >> There are some links to useful papers in this discussion:
> >>http://www.hydrogenaudio.org/forums/lofiversion/index.php/t47154.html
>
> >The wikipedia page tell some of the problems with A weighting,
> >though not so much for solutions.
>
> >I was just wondering, if you take two similar but different audio
> >signals and switch between them at, say, 1kHz, how the sound
> >changes with relative amplitude.  Assuming no definite phase
> >relationship between the two.
>
> None of these weighting schemes capture much of the perceptual element.
> That factor which makes us want to turn up the radio when a great piece of
> music comes on, because it sounds so much quieter than the Barry Manilow
> song which preceded it. Your 1kHz chopped signals will probably sound
> horrible, and are therefore likely to be perceived as loud.
>
> Steve

From: Robert Orban on 16 Jun 2010 22:01
In article <9c38ac81-c056-4f7d-94ed-
d607291d0304(a)s4g2000prh.googlegroups.com>, snickell(a)gmail.com says...
>
>
>I'm trying to A/B test a filter, and I'd like to control for the human
>preference for louder signals. Is there a standard way to do this?
>Right now I'm normalizing to the avg RMS level of the a-weighted
>signal. I'm hoping to achieve two signals with the same subjective
>loudness so there's no 'louder signal' bias.
>
>I'm a-weighting the signal before measuring the RMS in an attempt to
>compensate for reduced sensitivity to low/high frequencies (as the
>filter dramatically alters the spectral content it seemed like
>normalizing to the straight RMS might still result in a different
>subjective loudness... e.g. if the two signals had the same avg power,
>but in one the energy went into 1khz and in the other the energy went
>into 40Hz?).
>
>Does this approach make sense to other people? Is there a better one?
>
>thanks,

This free software should help:

http://www.orban.com/meter/

First  |  Prev  | 
Pages: 1 2 3
Prev: Calc freqs of triple tuned bandpass filters?
Next: generating a coherent signal