Only among deoderant.
Roll off referes to the ends of the frequency spectrum. Per your example, a roll off BELOW 300Hz would be to remove all content below 300Hz at some rate (6dB per octave, 12dB per octave or whatever. This pertains to how steep the content is attenuated). The same thing applies to roll off ABOVE the stated frequency. You could roll off everything above a given freq. Get it?