|MadSci Network: Anatomy|
This is an interesting question. The answer is it depends on why they are mute. Being mute means that you can’t or don’t talk and as you can imagine there could be lots of reasons for this. I'll talk a little about muteness and then I'll talk more about how the vocal tract and coughing, whispering and talking work in general.
There are lots of reasons that somone could be mute (or partly mute). There could be something wrong with the vocal organs (the parts of your body that are involved in talking, like your tongue, jaw, lips and larynx). They may not use spoken language to communicate because they are deaf. Or, there may have been a brain injury that prevents them from controlling the vocal organs or prevents them from using language in general. For an interesting story about one type of cognitive dysfunction that results in muteness read this article by Scott Adams, the writer of the Dilbert cartoons.
If one of these resons is why a person is mute then yes, they would make sounds when they cough. Coughing is just pushing a lot of air against the back of your throat all at once and everyone should be able to do this.
Whispering is a little trickier. Some people who can't talk normally may be able to whisper as in the case of Scott Adams above, but that would depend again on what kind of dysfunction they had. Someone who uses a signed language like American Sign Language rather than a spoken language like English to communicate could technically whisper, but they probably wouldn’t.
The other major reason that someone could lose the use of their voice is through damage to the actual parts that make sound, mainly the larynx. There are several disorders that can cause damage. For a brief description of some of these disorders you can look at the University of Utah Health Sciences Centre. To see some (graphic) videos of actual larynxs and disorders go to www.entusa.com.
To understand how this affects speaking and whispering you need to understand how we make sounds to speak.
In general there are two ways that you make sounds when you’re speaking. One is to push air through the vocal folds in your larynx (this is right behind your adam’s apple or thyroid cartilage. For pictures and more detail click here). These folds vibrate making sound a bit like the strings on a guitar make a sound (this is the sound generator). This sound is then shaped by moving your tongue and jaw to create different sized cavities. The cavities resonate like the body of a guitar or like the air in a jar when you blow across the top (sound resonators). You use your vocal folds to generate sound all the time when you’re talking normally and if you hold your fingers to the side of your adam’s apple while you talk you can actually feel the vibration of the vocal folds.
The other way that sound is created when you talk is by making a small constriction somewhere in your mouth and pushing a lot of air through it. This is what you do when you make a ‘f’ ‘s’ or ‘sh’ sound. These sounds don't require vibrating vocal folds. You can also make very quiet sounds by pushing air through the vocal folds but leaving them loose so they don’t vibrate (similar to just normal breathing but with more air). This is what you do when you’re making the creepy heavy breathing sound or an ‘h’ sound. This is also what you do when you whisper. You open the vocal folds so that they don’t make much sound but you still make the hissing sounds of ‘f’ ‘s’ and ‘sh’ as you talk. If you listen to someone whispering you’ll notice that sounds like ‘s’ are much louder than the other sounds because they aren’t affected by the open vocal folds.
So, if someone has trouble talking because they have damage to the vocal folds in their larynx, they should still be able to whisper. They should also still be able to cough.
If you are interested in learning more about how we speak, google for “speech and hearing sciences” or “phonetics”.
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