Re: Adjusting Peak, Average, Mean Curves -- Har-Bal Tech Tips and Suggestions

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Subject: Re: Adjusting Peak, Average, Mean Curves

Author:
Har-Bal

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Date Posted: 05:38:06 09/02/03 Tue
In reply to: kylen 's message, "Adjusting Peak, Average, Mean Curves" on 11:56:14 09/01/03 Mon

>Hi Har-Bal,
>The manual states that I can select either of these
>curves on the spectrum by hitting the tab button with
>the gain cursor selected.
>
>I'm able to switch between these 3 curves ok. Is there
>any reason or advantage to work on the Peak curve as
>opposed to the Average curve ?
>
>I notice that there may be a peak on the 'Peak' curve
>that is not on the 'Average' curve. I can adjust the
>Peak curves' peak down and it affects the Average
>curve. If I adjust a peak on the Average curve it does
>not always affect the Peak curve in the same way.
>
>I'm only building a single para type filter right ? Or
>is there some type of dynamic adjustment happening in
>there also that affects the Peaks differently ?
>
>I guess when I bring a reference file in then I could
>also see the range of dynamic headroom that exists in
>the reference between the average and peak of the
>envelope. But that's dynamic headroom - I guess that
>has an effect on loudness too so maybe that'll get
>clearer later when I try to balance a project.
>
>Just curious.
>Thanks,
>kylen

The three traces are inexorably connected so that if you apply a filter to one that same filter is applied to all. To have a clear idea on what the difference is between the peak and the average spectrums requires a bit of an understanding on how the spectrum is measured in the first place. The way Har-Bal does it is the traditional FFT spectrum estimation approach of taking windows (short time frames 16384 samples long) and calculating a periodogram for it. A periodogram is
just the magnitude squared of the discrete Fourier transform of the windowed data. Now the average spectrum comes about through averaging all periodograms together for the entire track. The peak spectrum comes from taking the peak spectrum magnitude from all periodograms for the entire track. The red trace is just the geometric mean between the two.

Why Har-Bal records both relates to how, in some music, problem resonances can stand out more in the peak spectrum than in the average one. An example might be a particularly strong instrument solo in the middle of a track that has one or two really loud resonances of short duration. If loud enough it will stand out in the peak spectrum but if they don't last long then they wont be very visible in the average one. Such a loud resonant peak might well be uncomfortable to listen to but if all you had to go by was the average trace then you might well find it difficult to figure out where the problem lies.

What I've found is that if you want the dynamics of the track to sound controlled then concentrate on the peak spectrum trace (yellow) and if you want to preserve the dynamics but just get the balance right use the average spectrum trace (green) and if you want a compromise use the geometric mean trace (red).

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Replies:

Subject	Author	Date
Re: Adjusting Peak, Average, Mean Curves	kylen	11:19:37 09/02/03 Tue
Re: Adjusting Peak, Average, Mean Curves -- kylen, 12:12:47 09/02/03 Tue Re: Adjusting Peak, Average, Mean Curves -- Har-Bal, 05:25:11 09/03/03 Wed