Frequency response correction

[siluet]

here is cell phone speaker frequency response curve, I want apply some corrections in Audacity via equalization, when making ringtones. Advices and suggestions appreciated.

[jagabo]

Assuming your plot was accurate (and it's probably not given the way you made it in your other thread), you would set the equalizer to do the opposite of the graph. Ie, boost audio below ~400 Hz, and attenuate above ~5000 Hz.

[siluet]

it's manufacturer's graph. From which frequency you suggested boost audio below ~400Hz, and how much?
Usually the recommendations is completely to suppress frequencies lower 300Hz, as small mobile speakers cannot reproduce lower frequencies lower than 100Hz, and may even be damaged. For high frequences above ~5000 Hz: would be okay to attenuate by -3db ?

[jagabo]

What are you trying to do? Pre-equalize an audio file so that it sounds better when played on the phone? Like I said, you want to equalize with a graph that's the exact opposite of that frequency response graph. You'll have to experiment a bit to decide where the low end cutoff should be. Oh, and sorry, I misread the graph the first time the low end rolloff starts around 900 Hz, not 400 Hz. You'll need about an 8 dB drop above 5000 Hz. I would concentrate on the range between about 500 and 10000 Hz.

[siluet]

say, to boost the lower frequencies from 300 Hz to 900 Hz by 6-8dB, and supress below 300 Hz?
This plot have no "0 dB", as base or a reference level for changing the volume of any frequencies, so it's not very handy.

[jagabo]

It's all relative. You just pick a nominal level so that the boosted lower frequencies don't blow out the signal.

[siluet]

How to convert Frequency Response plot into curve which show +/- dB values relative to "0"dB line?