Listening with your eyes? How to read graphs.

amirm

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Julf

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I agree about the annoying limitation on length of music that can be sampled. But the fact that spectral analysis can be confusing if you don't know what you are looking at is not the fault of the tool....
 

amirm

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Well it is if it won't let you change the vertical scale as in that graph. At least I have not found a way to get it to go lower so that I can see the spectrum.
 

Julf

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Well it is if it won't let you change the vertical scale as in that graph. At least I have not found a way to get it to go lower so that I can see the spectrum.

Not sure you need to get lower than -90 dB if you can see a brickwall-steepness drop at 22.5 Khz...
 

Bruce B

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Not sure you need to get lower than -90 dB if you can see a brickwall-steepness drop at 22.5 Khz...

Yes you do... I've seen many hi-rez files where the engineer has applied a filter to a 24/96 or DSD file to filter out UHF noise. You need to go down at least to -144dB with a 24-bit file.

Look at my Post #2. This is a DSD file where I have just applied a filter. If you only went to -90dB, you would swear it's an upsampled file!

The graph on Post #3, you wouldn't see any content above 10k if you only went down to -90dB
 

fas42

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Well it is if it won't let you change the vertical scale as in that graph. At least I have not found a way to get it to go lower so that I can see the spectrum.
I was sure this was mentioned once before, Amir. Audacity is "smart" enough to know what information is, or may be present, and alters the vertical scale as necessary. A possible key thing is to make sure that the preferences setting for Spectrograms has sufficient dynamic range, I've got mine set to 144dB. I'm just looking at a waveform posted by Bruce some time ago, it's having no trouble telling me that the track has a level of about 148dB down at 86kHz ...

Frank
 

amirm

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I post the side-by-side in the other thread . Here it is again:



In my book it is chopping off useful information.
 

Julf

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In my book it is chopping off useful information.

Well, yes, if you have set it to 96 dB of scale. But as Frank points out, you can set it to 144 dB.
 

Julf

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Yes you do... I've seen many hi-rez files where the engineer has applied a filter to a 24/96 or DSD file to filter out UHF noise. You need to go down at least to -144dB with a 24-bit file.

And that is something Audacity can so if you change the default setting.

Look at my Post #2. This is a DSD file where I have just applied a filter. If you only went to -90dB, you would swear it's an upsampled file!

Instead of just filtered in an extremely heavy-handed way. OK, not as bad as upsampled, but not much better.

The graph on Post #3, you wouldn't see any content above 10k if you only went down to -90dB

Well, "no significant content beyond 10k" is also valuable information. Something that might be OK if the original master tape is from the 60's, but a reasonably modern master should have much more HF content.
 

Bruce B

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Well, "no significant content beyond 10k" is also valuable information. Something that might be OK if the original master tape is from the 60's, but a reasonably modern master should have much more HF content.

This was a Classical recording from the 90's at a very low amplitude.
 

Julf

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Lay My Burden Dow&#.jpg

OK, here is a 2011 recording, "Lay My Burden Down" from "Paper Airplane" by Alison Krauss & Union Station from HDTracks. Does not look pretty, but I don't think you can blame Audacity for the ugliness - the ugliness probably happened in the copying room.
 

amirm

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Well, yes, if you have set it to 96 dB of scale. But as Frank points out, you can set it to 144 dB.
I have changed it and it will make no difference on the sample file. If I feed a program 24 bit files as I am doing, I expect it to be that way anyway. Without it, we have tons of people complaining about stuff using that program for no reason.

Welcome to the forum by the way :).
 

Julf

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I have changed it and it will make no difference on the sample file. If I feed a program 24 bit files as I am doing, I expect it to be that way anyway. Without it, we have tons of people complaining about stuff using that program for no reason.

That is why we need to help users with their settings. I find this link on computeraudiophile very useful.

Welcome to the forum by the way :).

Thanks! :)

Julf
 

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