Looking for suggestions for graph metrics

[John Mulcahy]

I've started looking at ways of providing some info about a selection of measurement data. In the example below I've selected a range of data (by pressing the shift key then clicking and dragging with the mouse) and I'm showing the slope of the selected region and the span of the data within it. What metrics would you like to see, and for which graphs?

 

[keantoken]

How about the Q value at the cursor, for instance if there is a peak or resonance on the chart?

 

[oliver]

In the SPL and Phase graph maybe the values that differ from a fixed value(1-2dB) for the higher peaks and valley(frequency, level and phase).

 

[AJ Soundfield]

Good question, since that appears to be a mid field/room measurement

 

[Antonio Di Motta]

It may also be interesting to make a calculation, with respect to the average, of the maximum and minimum db value. For example, on the posted graph, find the average value between the levels of 85db and 72db (extreme values of the straight line) and check the maximum excursion and the frequency in which they occur.

 

[EarlK]

Hi John,

If I understand you correctly ( as to how to create that "Slope Line" within the SPL + Phase window ) ;

- I'd like to see the 2 frequencies listed that correspond to the "start and end points" chosen ( when Shift-Clicking, Drag and Releasing ).

Also:

Is it possible to display more than one line ( maybe by adding a number key into the shift-click sequence )??

The reason I ask is that your displayed example shows 3 distinct slopes ( the HiPass , the general slope or trend of the speaker from 43hz to 5500hz and then another distinct roll-off starting at 5500hz ).

I would find it useful to be able to display ( and then analyze ) the different slopes one encounters when designing passive filters for speaker boxes having multiple drivers.

 

[John Mulcahy]

Multiple selections are not on the menu, but I have added the frequency range and lines showing +/- 3dB:

 

[EarlK]

Looks Good John!

Earl

 

[3ll3d00d]

the above would be nice as a feed into EQ

i.e. make the +/- x dB boundary user configurable and allow the user to adjust the target slope then ask the EQ to generate filters to make it fit

 

[AJ Soundfield]

the above would be nice as a feed into EQ

No sir. That is precisely not what one would want to do with a non near-field single axis pressure measurement, hence my previous comment.
Unfortunately that is the latest fashion in audiophile/studiophile circles.

cheers

 

[3ll3d00d]

Who said anything about a single measurement? Not me at least, regardless the point is to add a potentially useful tool, if the user wants to abuse that them that's up them.

 

[AJ Soundfield]

the above would be nice as a feed into EQ
Who said anything about a single measurement? Not me at least, regardless the point is to add a potentially useful tool, if the user wants to abuse that them that's up them.

The above is a single measurement. Worse, it appears non near field.
I agree there is potential use...and far more common potential misuse, like feeding through EQ and hammering flat. Extremely fashionable these days. But misguided. As you said though and I suspect Johns intent, merely "a" tool.

cheers

 

[AJ Soundfield]

Why I say it is misguided

If one has REW/measurement capability, the ideal is to measure the native response in the 1m range out to at least 60 degrees, then manually and judiciously apply the EQ on design axis, while carefully noting what is happening off axis.
So back to the context of what John is asking from strictly a useful "tool/feature" standpoint, I'm not really sure what the answer is

cheers

 

[John Mulcahy]

Don't get too carried away by the example graph, it was just to illustrate an ability to measure a slope. The use which prompted that feature was measuring acoustic rolloffs to help with crossover design, but folk can use it for any purpose they like.

 

[AJ Soundfield]

Ah, so it can approximate db/oct over a selected range?

edit, never mind, see it at top now. neat, thanks

 

[John Mulcahy]

For the filtered IR graph the selected range shows the Schroeder integral regression line and T60 time:

 

[Adhoc]

Seems to be nice planned addition to REW. Not to do with above but one request I have is if it's possible to have a button for "Uncheck all boxes" for already made measurments when opening a file of saved measurements. Reason: It is quite tedious to manually uncheck say 50 measurements from yesterdays measurements for Impulse, ETC and RT in the Overlay. 50 measurements shown at once on the screen is a mess to look at.

When analysing / comparing the measurements, one versus the other, I keep the best one, then move on for a new possibly better one. If yes, I uncheck the preivious good one. (I make 1 and only 1 change between each measurement, like moving the mic 10 cm / 4", adjusting the angle of a reflector another 5 degrees, etc. When that is done for left only, right only and left + right together, one quickly gets loads of measurements. If such a button / command already exist, I am not of aware of it.)

Another nice feature would be if "Show Data Panel" in Filtered IR could be shown in the upper right hand corner, instead of to the far left where usually more interesting info is shown in the diagram

 

[John Mulcahy]

Not to do with above but one request I have is if it's possible to have a button for "Uncheck all boxes" for already made measurments when opening a file of saved measurements.

Right click in the legend area, as mentioned in the hints.

 

[EarlK]

Hi John,

Have these graphics metrics been newly disabled//broken ( or is it just me and my setup )??

eg. I know that sometime this 2022 year I measured the distance between two peaks belonging to 2 separate impulses ( within the overlays section ) to determine linear distance ( Acoustic Centres actually ).

Thanks, Earl

 

[John Mulcahy]

Different tool, that one is Ctrl + right click and drag.

 

[EarlK]

Thanks John ( sorry to bother you with my bad-brain day ).

EK

 

[Zozo]

Can someone, help me? I'm trying to generate a slope for my measured curve but after successfully defining the range by shift+left mouse drag, I only get this message on the top left corner of this range:
"Metrics are not available for this graph
To request/suggest metrics use the REW forum at AVNirvana.com"
I tried it on several measurements. All of them are pretty flat, +/-5dB, slightly downward sloping, so there is no way that the algorithm cannot match a curve.
What am I not doing, or doing wrong?

 

[thothsong]

You want to be in the SPL & Phase graph for metrics.

 

[Zozo]

Oh, now it works Thank you!