[Beagle]

Seems to be a very common thing. Anyone know why? Why not 6 or 14kHz? Is it diaphragm material or plastic that resonates at that frequency?
 
 

 

[Mad Max]

As long as the spike's not too strong, I'm fine with it.  =p

 

[Beagle]

Didn't think anyone would have a clue here..

 

[Radio_head]

I remember Tyll explaining the peaks/valleys in that region as being resonances between the driver and the ear, the concha, and inside the ear canal itself.  While the driver is could be putting out a flat frequency, the resonances make the measurements appear as if it isn't.  Apparently minor position shifts on the dummy head can cause quite a bit of variability in those frequencies as the position of the ear relative to the driver has shifted, thus altering the resonance.  
 
 
I think all this info is in one of the innerfidelity articles if you look at the back catalog.

 

[extrabigmehdi]

I think the problem doesn't happen as often with open headphone. With the hd598, seems even the contrary problem.

 

[drtturnip]

My guess is that it gives a little bit of sizzle at a frequency that young and old can hear. If you had most people compare a flat response headphone to one with a bump at 10k I bet most would think the bumped one sounded better.  Consumer speakers often have the same thing.

 

[manveru]

No idea why, but that has been one of my biggest pet peeves since I got into headphones. Glad somebody else noticed, haha. I always have to EQ those spikes down if they are there.
 
Also, I've noticed that the spike is usually centered around 9kHz.

 

[Danthrax]

What looks like a spike is actually a more gradual increase if you make all of the increments on that chart evenly spaced. 

 

[TMRaven]

They're already spaced properly.  The graphs account for musical octaves.  As for why not 6khz, I thought it was a common practice among the audiophile headphones sennheiser offers to peak at 6khz-- right in the region of sibilance :S