Density of modes graph from phonon dispersion graph

[PhysicsGirl90]

While practicing for an upcoming exam, i ran into this question that has truly got me stumped. A phonon dispersion graph is given for NiAl (attached), and then they ask you to schematicaly plot the density of modes graph. I have the result of what is should look like, but i do not understand how to get from A to B.

Can someone point me in the right direction as to how i should go about doing this?

 

[haruspex]

I know nothing of this subject, but from the 'density' term and just looking at the graphs here's my guess.
The density is high for the frequencies where the provided graphs 'spend' a lot of time. This is where the gradient is low. So you get very high peaks in density at 4 (lower middle graph) up to 5.75 (all three lower graphs) and 8-10.5 (upper graphs).