The fact that the pronunciation of the forms pack and back leads to a distinction in meaning can only be due to the difference between the p and the b sounds in English. This property of language is described as discreteness. Each sound in the language is treated as discrete. It is possible, in fact, to produce a range of sounds in a continuous stream which are all generally like the p and b sounds. These physically different sounds could be conceived of as the spoken counterpart of a written set such as.