Dysarthria is a speech disorder that causes unclear or slurred speech due to weakness in the muscles used for speaking, such as your lips, tongue, vocal cords, and chest muscles. It affects how clearly you can speak, but doesn't impact your ability to understand language or think of what you want to say. Common signs include slurred speech, reduced volume, speaking too fast or too slowly, sounding nasal, having a hoarse or monotone voice quality, and speaking in short phrases due to breathlessness. The specific combination varies depending on which muscles are affected. Dysarthria results from conditions that weaken or impair control of the speech muscles, such as stroke, brain injury, Parkinson's disease, multiple sclerosis, cerebral palsy, or other neurological conditions affecting muscle function.