REW graph question

[scottie666]

Hi all,

thanks in advance for the attention, and my apology if the question has been asked earlier here in the forum - i am a beginner into REW and acoustic measurement in general.

well, refer to the attached graph that i took with REW, it starts with a very high SPL from 20hz, is that a normal behaviour? to my understanding, a normal measurement would start with very low SPL with 20hz and gradually ramping up to "normal" SPL towards say 40 - 60hz...
if it is not normal, any tips for me to look into from measurement point of view?

as you can see, there are big dips between 100 - 300 hz, so i want to understand the validity of the measurement, as the dips need to be addressed somehow if that is the case...

Cheers!

 

[sam_adams]

In your attached graph you have the vertical scaling set to 90dB. Limit your vertical scaling to 50dB. Start with an unsmoothed measurement and set the top of the scale to 5dB above the highest peak. Set the lower limit of the scale to 50dB below the upper limit.

Examples:

50dB vertical scale, unsmoothed:

50dB vertical scale, 1/24 smoothing:

 

[sm52]

sam_adams
it seems the question was as follows. 'Can you believe such a graph?'. Changing the scaling does not answer this question in any way.

scottie666
Listen to individual tones from 20 Hz to 80 Hz. If you hear them at approximately the same volume, then the graph is correct.

 

[scottie666]

Listen to individual tones from 20 Hz to 80 Hz. If you hear them at approximately the same volume, then the graph is correct.

thanks, will try.