[KElyas]

I've heard it for highs as well so I'm assuming it can describe any frequency?

 

[Tsujigiri]

It has to do with the volume sharply decreasing at the ends of the frequency spectrum. So, many headphones will have a large amount of mid-bass, but not so many will have the bass extend all the way to the deepest sub-bass. Same thing with the treble. It's just about the extension a headphone has into the frequency extremes.

 

[Sound Quest]

All it would mean is that the bass doesn't go down very low.
 
That doesn't mean that the headphones will lack impact in any way, as impact seems to be accociated more with the mid-bass and not the sub-bass. However, the bass extention would suffer a fair bit..

 

[KElyas]

oh right, thanks guys