In most cases the cause is unknown. However, there are various known causes of speech impairments, such as hearing loss, neurological disorders, brain injury, an increase in mental strain, constant bullying, intellectual disability, substance use disorder, physical impairments such as cleft lip and palate, and vocal abuse or misuse.
Speech disorder
Language disorder
Speech and language impairment
Speech delay
Motor speech disorders
Language delay
Infantile speech
Nonverbal learning disorder