Speaking difficulty is a disorder that is a result of damage to the muscles and nerves that allow a person to speak. The damaged nerves and muscles impair the mouth, tongue and larynx, because of which the speaking ability in a person is impaired. The causes are brain damage and damage to the nerves associated with speech. Speaking softly, mumbling, slurring and strained voice are symptoms of this disorder. Routine activities like chewing, moving lips and swallowing can also be affected.