Around two thirds of people with Parkinson’s have difficulties with their speech, especially speaking loudly enough for others to hear. Less than a third of people with Parkinson’s who have speech problems are offered speech and language therapy, because there is not currently good evidence for its effectiveness. Funded by National Institute for Health Research (NIHR) This new five-year, randomised controlled trial will evaluate the effectiveness and value for money of speech and language therapy. The researchers hope if this study shows positive results it will enable and encourage more patients with Parkinson’s to receive this therapy in the NHS. The study will recruit 546 people with Parkinson’s who have difficulty with their speech or voice. They will be randomised into three groups: a control group and two groups who will receive speech therapy (standard NHS speech therapy or Lee Silverman Voice Treatment). Participants will be followed up over a year to assess if the treatment improves their ability to communicate or their quality of life