A bit of egg on my face

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richardh08
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A bit of egg on my face

Post by richardh08 »

Over the last couple of years, I've been measuring the loudness of dragon egg reports, as part of trying to create new compositions and to gain some level of understanding of how crackle works. Although the measurements - calculated from the sound amplitude and duration - seem to be broadly in agreement with what my ears tell me, there have been many cases where the numerical results were more variable than I would have expected. I put it down to uncontrollable random factors. Since I need to use my judgement when determining just what values best represent the amplitudes and durations, I've always been aware that there is an element of subjectivity in the measurements. Perhaps that's why I've been prepared to accept the variability.

Well, it's only taken me two years to realise that there are some hidden systematic errors. It turns out that the software I use performs behind-the-scenes scaling on the amplitudes, and the scaling factors appear to be unpredictable (at least, by me). Fortunately, it doesn't fundamentally affect the research that Ken and I have been doing (we do, after all, each possess a pair of ears) but it has caused rather more confusion in my mind than might otherwise have been the case.

Further investigation indicated that all the commercial software I've used to read the audio files performs some sort of amplitude scaling - the worst case I've come across (not one that I've used in my measurements) scales all amplitudes to lie in the range 0 to 1, regardless of their original values.

Over the last week or so I've written my own software to extract raw amplitude data, which then allows me to apply a correction factor to the data. So far, I've only applied the method to a small number of measurements, but the improvement in consistency looks promising. For example, tests of the same composition with two different primes gave uncorrected loudness measurements of 1.8 and 0.7 but, after applying a scale factor correction, the values came out at 2.4 and 2.3!

I suppose what I really ought to do is bite the bullet and write some software that fully automates the measurements.
Even when I'm wrong, I'm convincing.
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Lloyd
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Re: A bit of egg on my face

Post by Lloyd »

Richard,
I use (the now fairly old) Sonar recording/editing suite, and a good Aiwa studio microphone. It does no compression unless you will it to do so.

Lloyd
"Pyro for Fun and Profit for More Than Sixty Years"
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richardh08
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Re: A bit of egg on my face

Post by richardh08 »

I guess I'll stick with my lifetime habit of making use of what I have :D

I'm reasonably certain that my video camera, with AGC turned off, and set to a constant attenuation, produces a consistent audio output. The main issue is, and clearly has been for some time, the post processing.

With a noisy output (in both senses of the word) it's always going to be a little tricky to pick out the parameters I need. Fortunately, I don't need high precision.

My current method, which is largely manual, seems now to be good enough, but it's somewhat tedious. If I go for the software-only option, I'll need to figure out how to extract reliable readings from waveforms that vary widely in their envelopes. That's not helped by the variety of background noises, including passing traffic and aircraft, my neighbours' kids and my other neighbour's more than occasional use of a chainsaw!
Even when I'm wrong, I'm convincing.
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Lloyd
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Re: A bit of egg on my face

Post by Lloyd »

You, sir, need some "acreage"! But, I'll bet that's pretty scarce in the British Isles these days.

'Lit a rocket for the kids yesterday, and of course it wind-vaned 400' toward the neighbor's yard. Only... it went that whole 400', and STILL landed inside my fence! ;)

LLoyd
"Pyro for Fun and Profit for More Than Sixty Years"
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richardh08
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Re: A bit of egg on my face

Post by richardh08 »

Grrr! Hugely envious!

My garden is long enough that I can put on the occasional reasonably ambitious show, but it's only about 60-odd feet wide. Fortunately, all my neighbours love fireworks - and, of course, they always get invited. They don't seem to mind the odd bit of debris landing on their properties.
Even when I'm wrong, I'm convincing.
Starfire
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Re: A bit of egg on my face

Post by Starfire »

Living on a old council estate, it's very seldom I see any of mine land on my property
No complaints yet and I've been here forty years.
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