The primary aim of the study is to evaluate the effect of an IACD i.e. Apple iPod-shuffle, on freezing and gait speed in people with a diagnosis of PD through the implementation of a randomised controlled trial. A secondary aim of the study is to evaluate the impact of such a device on the quality of life of people with stroke through the administration of a self-report questionnaire. The IACD will be pre-loaded with an individualised auditory cueing frequency (metronome sound) matched to the walking speed of the individual with PD.