Researcher holding two male toads. On the right, the male toad has a very clear vocal sac due to exposure to noise pollution for ten days. The toad on the left, from a control group not exposed to noise pollution, has a more orange coloured sac. These differences has caused female toads no longer able to decide which male to mate with on the basis of the colour of the vocal sac. This could lead to the rapid deterioration in genetic quality of the population, causing a collapse of populations in time.