The most common and popular method for shunting a portion of the amplified low frequencies is to enlarge the venting in orderly steps to 3- to 4-mm diameter and greater. Or, if more convenient, by shortening the length of the vent. In the latter case, incidentally, there will be additional reduction of low frequencies occur due to an increase in slit leak.3,19,27,70,81 Both methods assume familiarity with bench modification techniques, covered in a later section