If this is a sound wave, the denser the medium, the faster the wave. For a light wave, the denser the medium, the slower the wave. It all depends on the medium through which it travels. The factor of the medium that plays a role on the velocity of a wave is its density. If this is a sound wave, the denser the medium, the faster the wave.
Mastitis is an infection of the tissue of the breast that occurs most frequently during the time of breastfeeding. This infection causes pain, swelling, redness, and increased temperature of the breast. It can occur when bacteria, often from the infant's mouth, enter a milk duct through a crack in the nipple. This causes an infection and painful inflammation of the breast.
Mastitis is nearly always caused by bacteria that invade the udder through the teat end and multiply there. Mastitis can be either clinical or sub-clinical. Clinical mastitis is mastitis in which an abnormality of the udder or secretion is observed. Clinical mastitis can be mild, moderate or severe.