…I’m just kind of curious, and I can’t find ANY information on Mutism in humans that’s not either Selective/Elective, or caused as a result of hearing impairment. Now, applying Murphy’s Law to the human body leads to the conclusion that Mutism by itself HAS to occur, at least occasionally. But how often?
Well, thanks for your time, and apologies in advance if I’ve inadvertently used offensive language,
Ranchoth
…really? Nothing? I’m speechless.
I’m sure lots of people are either born with or develop problems with their throat/ voicebox that prevents them from speaking. Is this what you mean?
I don’t have any hard numbers, but can tell you about a number of disorders which make speech difficult.
This Rochester Clinic mentions a number of speech disorders in adults which affect the ability to speak:
I don’t know how comprehensive the list is, but other sources seem to suggest it lists most of the conditions.
Cancer of the larynx, strokes, head trauma, brain tumors and other brain damage are the main reasons for speech problems, although some children are born with them. Cerebral Palsy is another condition affecting speech: some people with CP cannot speak at all while most have some problems.
According to the (American) National Aphasia Association, one million Americans have aphasia, which impairs but may not prevent speech, and is due mainly to strokes and head-injuries.
Dysarthria has a number of causes, but tends to make speech difficult rather than impossible. Source.
Apraxia of speech is generally treatable in children, and they can learn to speak to at least some degree (see here and here). It can also occur in adults as a result of brain damage (stroke, trauma, tumors, etc.).
Removal of the larynx (voice box) need not prevent people from speaking, with electronic aids or oesophagal speech, so you should probably not count them.
Although I can’t find statistics on how many people are actually unable to speak due to the above disorders, it seems that vocal problems fall into 3 main categories: (1) psychological ones like stuttering and elective mutism; (2) localised problems like having your larynx removed, which is largely treatable; and (3) the consquences of ailments which affect a wide range of mental or physical functioning, such as Parkinson’s disease, and the aftermath of strokes, meningitis and other brain damage - in the last case, the patient is likely to be seriously ill in other ways.
Of course it should be noted that many deaf people have some hearing, and it is difficult to separate people with extreme difficulty speaking from those entirely unable to speak, so coming up with precise figures will be difficult.
For more information on speech and language disorders see American Speech-Language-Hearing Association.