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 doesn't harm the baby during breastfeeding, even if you have an infection. Mastitis can also affect women who are not breastfeeding but have an infected breast. This can be due to bacteria entering the breast through piercings or through cracks in the skin or the nipple, often in younger women and smokers. Shortening of the milk ducts towards menopause can also lead to mastitis.