Final answer:
Parkinson's disease is a neurodegenerative disorder that affects the central nervous system, leading to tremors, rigidity, and slowness of movement. It particularly impairs speech, causing a softer, monotone voice and difficulty with speech movements. The loss of dopamine neurons in the substantia nigra is responsible for these motor symptoms.
Step-by-step explanation:
Parkinson's Disease and Its Effect on Voice
Parkinson's disease is a degenerative disorder of the central nervous system which primarily impairs the muscular system and movement. Key symptoms include muscle tremor, rigidity, bradykinesia (slowness of movement), and postural instability. Parkinson's disease is characterized by the loss of dopamine neurons in the substantia nigra, which controls movement. This neuronal loss results in motor symptoms such as tremors, slowed movement, and muscle rigidity. One of the affected aspects of motor control is speech. The disease can lead to a soft, monotone voice, reduced pitch and volume, and a hesitancy before speaking. Patients may have difficulty with the rapid and precise movements required for normal speech, resulting in a condition known as hypokinetic dysarthria. As Parkinson's progresses, medications may become less effective, and psychological symptoms, including depression and dementia, may develop.