What frequencies of sound are most affected by the use of ear plugs?

Question

Ear buds are used to protect hearing loss and such but they seem to block out certain bands of audio frequencies more that others. When i play my drum set with the plugs in the drums all sound tighter and nicer in general so if i can figure out which frequencies are affected most by the ear plugs i can try plugging that info into my EQ.

Answer 1

Low frequency sounds.  

Answer 2

High frequencies.  Earplugs are small.  Low frequencies (bass) take lots of energy to make and lots of material to stop once they're going.