Re: [LAD] Calculate R M S

On Fri, Feb 18, 2011 at 1:20 PM, Fons Adriaensen <fons@email-addr-hidden> wrote:
> On Fri, Feb 18, 2011 at 11:30:24AM -0800, Mark Knecht wrote:
>> On Wed, Feb 16, 2011 at 10:45 AM, Fons Adriaensen <fons@email-addr-hidden> wrote:
>> <SNIP>
>> >
>> > Some filtering followed by RMS detection will provide a good
>> > approximation to subjective loudness.
>> >
>> <SNIP>
>>
>> Is this part to implement something like like Fletcher-Munson curves?
>
> In general that is not the case, probably because for most types of
> content the mid-frequency range is dominant. And loudness measuring
> systems are expected to give good results for typical content, not
> to estimate the subjective loudness of single tones or narrow band
> signals.
>
> The filter recommended by the ITU and EBU is a combination of a 2nd
> order highpass (around 50 Hz) and a shelf filter providing 4 dB gain
> at 4 kHz and above. Listening tests have shown this to work quite
> well in practice.
>
> Ciao,
>
> --
> FA

Interesting. Thanks.

I would guess that this sort of solution makes some sort of assumption
of what the actual SPL is. Without that it seems at first blush (to
me) to be not that accurate in an uncalibrated environment, or do you
offer some way to calibrate the meter prior to depending on it? I know
I was pretty surprised how loud 85db SPL was when I got ahold of
calibrated equipment to test with.

I'll look forward to playing with your tools when you release them.

Thanks,
Mark
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Received on Sat Feb 19 04:15:02 2011