This dissertation investigates imitation in speech, which is the general tendency shown by a speaker to become more similar to another speaker in the way they speak. Many of us have experienced this while talking to someone who is speaking the same language but with a different accent. Conversing with such a person can affect some characteristics of our speech, so that we come to sound more like them. Imitation in speech has been very extensively studied, especially over recent years. To contribute to this line of research we provide an account of imitation in speech at the allophonic level, that is at the level of the possible phonetic realisations of a phoneme. We are interested in whether imitation of the sound of a given phoneme in a particular word position can influence the other possible realisations of that phoneme in the same word position. We are also interested in determining whether imitation of a speech sound in a particular word position for a given phoneme can affect the realisations of that phoneme in a different word position.