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Is headphone harmonic distortion correction possible?

jamesbond007

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Hello. On Rtings reviews there are weighted harmonic distortion graphs. Could we use that data to somehow modify the audio signal to try to remove the harmonic distortion? If so, is there a program or maybe a Matlab/Python script that applies such correction to audio files? Would there be any audible difference?
 

Jimbob54

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Doesnt directly answer your question but interesting https://www.audiosciencereview.com/...hones-thd-and-the-magic-1-safety-limit.21027/

I would guess (but not an engineer or at all knowledgeable) that distortion characteristics are baked into the headphone and its behaviour and the only way to change that is either a physical mod (which will of course bring perhaps different problems) or reducing the amplitude of the incoming signal at frequencies the HP struggles with- which is DSP/ EQ and of course changes the music.

In other words, better to buy a HP that exhibits low distortion for the volumes and types of music you play on them.
 

thewas

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It can be done, but usually HD isn't an audible problem on decent headphones and reasonable listening levels.

 

Jimbob54

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Perhaps it is possible then. Not sure how bad the headphone distortion would have to be to begin to consider this though
 

staticV3

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definitely possible when doing measurement sweeps, but I imagine doing the same with actual music will massively complicate things.
 

kemmler3D

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Could we use that data to somehow modify the audio signal to try to remove the harmonic distortion?
The answer is really no, harmonic distortion is a nonlinear phenomenon which basically means you've added something that wasn't there before, instead of just moving the original signal around in time or amplitude.

Frequency response is correctable using EQ, same with phase response.

However, distortion doesn't really work the same way. It adds energy at new frequencies. So to remove THD that occurs from a 1khz input, you need to somehow remove the distortion that pops up at 2, 3, 4, 5 khz. But how to do that without affecting the normal, intended sound at 2-5khz ? Your adjustment would need to vary depending on the input at 1khz. And this is a different and much more complex tech altogether than the EQ or FIR that we are accustomed to. In fact, I am not aware of any tools that do this.

You can minimize distortion using EQ by lowering the signal in areas with high distortion. However, you're also changing the FR that way.

There is no way I know of to remove distortion by itself.
 

kongwee

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By algorithm, it is how you can remove aliasing in sound synthesis. However, it is questionable to worth the effort. It is part of sound. For headphone, if you touch the harmonic content your timbre will be affect too. It is a different beast from EQing.
 

pma

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Could we use that data to somehow modify the audio signal to try to remove the harmonic distortion? If so, is there a program or maybe a Matlab/Python script that applies such correction to audio files? Would there be any audible difference?

Harmonic distortion of good headphones is low enough and is below audibility threshold. BTW, harmonic distortion of good headphones is much lower than the intrinsic harmonic distortion of human ear.
 
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