Can I get the early and late frequency response and cumulative energy time from REW?

[MengW]

There is the early and late frequency response in Genelec GRADE report.

I can use the IR windows of REW and get the frequency response of 0-20ms above 50Hz, but, cannot change the Left window value in IR windows to negative, such as -20ms, to get the curve after 20 ms.

I found out the Cumulative Energy Time from Dr. Floyd Toole paper (The Measurement and Calibration of Sound Reproducing Systems) and Leembruggen SMPTE report

AES E-Library » The Measurement and Calibration of Sound Reproducing Systems

For decades, it has been widely accepted that a steady-state amplitude response measured with an omnidirectional microphone at the listening location in a room is an important indicator of how an audio system will sound. This paper examines both small and large venues, home theaters to cinemas...

www.aes.org

https://f.hubspotusercontent00.net/hubfs/5253154/er0994-2014.pdf

Do you think I can get some similar information from REW?

There is one data named Peak energy time in REW Spectrogram Graph. Do you think it's close to the cumulative energy time?

Spectrogram Graph

Thanks.

 

[ernestcarl]

There is the early and late frequency response in Genelec GRADE report.

I can use the IR windows of REW and get the frequency response of 0-20ms above 50Hz, but, cannot change the Left window value in IR windows to negative, such as -20ms, to get the curve after 20 ms.


View attachment 280574


I found out the cumulative energy time from Dr. Floyd Toole paper (The Measurement and Calibration of Sound Reproducing Systems) and Leembruggen SMPTE report

AES E-Library » The Measurement and Calibration of Sound Reproducing Systems

For decades, it has been widely accepted that a steady-state amplitude response measured with an omnidirectional microphone at the listening location in a room is an important indicator of how an audio system will sound. This paper examines both small and large venues, home theaters to cinemas...

www.aes.org

https://f.hubspotusercontent00.net/hubfs/5253154/er0994-2014.pdf

Do you think I can get some similar information from REW?

There is one data named Peak energy time in REW Spectrogram Graph. Do you think it's close to the cumulative energy time?

Spectrogram Graph

View attachment 280577

Thanks.

You should get something similar to the "early" FR curve by applying a FDW of 5-7 cycles, and maybe 1/3 to 1/6 smoothing.

By adjusting the "rise time" to anywhere between 10-30ms, the second trace (20ms trace) in the cumulative spectral decay view can be considered as your "late" FR curve.

The full FR curve you could choose either 1/6 or 1/3 smoothing -- as will become apparent, REW does not have an option for applying manually adjustable sliding scale algorithms in its filters so you'd have to make do with whatever smoothing options are available...

If you want to overlay all three curves simultaneously, you'll need to manually create a separate copy of the full FR curve in order to apply FDW (early FR), as well as extract the 20ms trace from the CSD view using a plot digitizer for your late FR curve.

Can't say what settings adjustment would give you the most similar result to Genelec's own graphs as I do not have my own Genelec monitors and accompanying GRADE report to contrast with...

 

[ernestcarl]

There is one data named Peak energy time in REW Spectrogram Graph. Do you think it's close to the cumulative energy time?
Spectrogram Graph

I dunno... that last plot kind of just looks like a frequency selective curve of the RT(?) Sorry, too lazy to read the PDF file. You "might" be able to get a similar or even better intuitive feel of a room by just using the spectrogram views. *Experience is needed here. Think of a doctor reading an x-ray or mammogram.

 

[MengW]

I dunno... that last plot kind of just looks like a frequency selective curve of the RT(?) Sorry, too lazy to read the PDF file. You "might" be able to get a similar or even better intuitive feel of a room by just using the spectrogram views. *Experience is needed here. Think of a doctor reading an x-ray or mammogram.

Thanks for your reply.

Cumulative energy time, the time taken after the arrival of the direct sound for the sound field to rise to the steady-state level.

From the report, I found that the correlation between Cumulative energy time and reverberation time (RT) is very strong in LF.

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[MengW]

You should get something similar to the "early" FR curve by applying a FDW of 5-7 cycles, and maybe 1/3 to 1/6 smoothing.

By adjusting the "rise time" to anywhere between 10-30ms, the second trace (20ms trace) in the cumulative spectral decay view can be considered as your "late" FR curve.

The full FR curve you could choose either 1/6 or 1/3 smoothing -- as will become apparent, REW does not have an option for applying manually adjustable sliding scale algorithms in its filters so you'd have to make do with whatever smoothing options are available...

If you want to overlay all three curves simultaneously, you'll need to manually create a separate copy of the full FR curve in order to apply FDW (early FR), as well as extract the 20ms trace from the CSD view using a plot digitizer for your late FR curve.

Can't say what settings adjustment would give you the most similar result to Genelec's own graphs as I do not have my own Genelec monitors and accompanying GRADE report to contrast with...

Yes, I found that it takes a lot of knowledge of acoustics and psychoacoustics to use REW well, and I think I will keep on studying hard.

Btw, currently, I still can't understand the different values of 1000Hz after 100ms, in RT60 decay, Decay, Spectrogram Fourier mode and Wavelet mode.

 

[JohnPM]

I can use the IR windows of REW and get the frequency response of 0-20ms above 50Hz, but, cannot change the Left window value in IR windows to negative, such as -20ms, to get the curve after 20 ms.

Just change the window reference time to move it. You can also drag the reference marker on the Impulse graph to reposition it.

 

[MengW]

Just change the window reference time to move it. You can also drag the reference marker on the Impulse graph to reposition it.

Wow, great~~~

Thanks!

 

[dasdoing]

There is one data named Peak energy time in REW Spectrogram Graph. Do you think it's close to the cumulative energy time?
Spectrogram Graph

Peak energy time would be the 0 point of this graph.

Peak energy time line is underrated imo. it might be the best meassure for in room phase correction

 

[MengW]

You should get something similar to the "early" FR curve by applying a FDW of 5-7 cycles, and maybe 1/3 to 1/6 smoothing.

By adjusting the "rise time" to anywhere between 10-30ms, the second trace (20ms trace) in the cumulative spectral decay view can be considered as your "late" FR curve.

The full FR curve you could choose either 1/6 or 1/3 smoothing -- as will become apparent, REW does not have an option for applying manually adjustable sliding scale algorithms in its filters so you'd have to make do with whatever smoothing options are available...

If you want to overlay all three curves simultaneously, you'll need to manually create a separate copy of the full FR curve in order to apply FDW (early FR), as well as extract the 20ms trace from the CSD view using a plot digitizer for your late FR curve.

Can't say what settings adjustment would give you the most similar result to Genelec's own graphs as I do not have my own Genelec monitors and accompanying GRADE report to contrast with...

Hello,

Follow the JohnPM's reply, I got the early and late curve with REW.

full -125~500ms, blue

early -125~20ms, red

late 20~500ms, green

Friend A, Polk audio SDA speakers+Dirac, less room acoustic treatment.
There are a lot of late energy.

Friend B, 2 way 8' speakers, with 6 pcs 1.8x0.6x0.1m absorption panels.

20~80ms green, 80~500ms grey.

20~80ms green, 20~500ms black.

8351+W371+AVAA+Polyester

Some notes in GRADE report.

And 100 Hz~10 kHz ratio mean result table.