Constraining the model
We have seen throughout this book that phonology is the study of the underlying organisation of the sound system of human language. We have also seen that phonology is not simply phonetics. Recall that phonetically [t], [th] and [ɾ] are distinct sounds, yet, at the same time, for American English these three sounds are related to a single underlying entity that can be symbolised as /t/. In order to make this argument, we need to assume a certain degree of abstraction. In other words, we need to abstract away from the differences between these sounds in the surface phonetics to their underlying similarities. This allows us to establish the underlying phoneme unifying these surface sounds and in the process capture the native speaker’s intuition that they are related.