14. A flexible noise attenuating cutting line for use in rotary vegetation trimmers, said line defining a substantially curvilinear outer surface, a central axis extending longitudinally therethrough and a pair of troughs in opposed disposition across said axis, said troughs extending helically along and about said line and defining at least 15 twists about said central axis per linear foot.33. A flexible noise attenuating cutting line for use in rotary vegetation trimmers, said line defining a central axis extending longitudinally therethrough and comprising a pair of laterally overlapping cylindrical portions disposed in a twisted disposition about said axis so as to define a pair of substantially V-shaped opposed troughs extending helically along and about the line.