Excited audience members in Australia. Stimulation or sensory excitation is the action of various agents or forms of energy (stimuli) on receptors that generate impulses that travel through nerves to the brain (afferents).
Voices are the most common type of hallucination in schizophrenia. Many people with the disorder hear voices. The voices may talk to the person about his or her behavior, order the person to do things, or warn the person of danger.
Hallucinations can be caused by schizophrenia, which is a mental illness; or Parkinson's disease, which is a nervous system disorder. If you or someone else is suffering from hallucinations, then you need to consult a doctor immediately.