7a. The vocal folds and voicing
The sounds of languages can be divided into voiced and voiceless or unvoiced (these two terms are used interchangeably). Vibration of the vocal cords or vocal folds produces a voiced sound. You can feel the vibrations of your vocal folds by placing your fingers over your throat while saying a sound like /zzzzzzzzz/, /vvvvvvvvvvvv/, /mmmmmmm/ or /ɑɑɑɑɑɑɑɑɑ/. But have you ever seen human vocal folds, vibrating or otherwise? It can be a bit of a jolt the first time you do. Well, get ready. At
the following two links you will see slow-motion videos and a
gif showing the vocal vibrating, in slow motion. This was
photographed using a stroboscope, or rapidly flashing
light:
http://www.youtube.com/watch?v=UpOXecWC5Dw
http://www.youtube.com/watch?v=Gv4evDGLgjQ
Note how they
demonstrate three ways to initiate a vowel sound: aspiration
('h'), a glottal stop, and 'zero onset', or a plain vowel. The
flap of flesh you see is not the tongue. What is it?
Here are some still pictures and a
video of the larynx:
http://www.gastrolab.net/pa-212.htm
And a gif:
http://www.phonetics.ucla.edu/vowels/chapter2/vibrating%20cords/vibrating.html
How do you think they filmed
these videos? This site shows you what a video laryngoscope is
and how it works:
http://vam.anest.ufl.edu/airwaydevice/storz/index.html
Here is an illustration of a
flexible fibre-laryngoscope; a flexible tube with a lens and
light on the end of it is inserted through the nasal passage
to give a view of the larynx:
https://www.youtube.com/watch?v=BrnW9xSc1Hw
You
can see the use of both these tools demonstrated in an
impressive video (towards the end) of the Acoustical Society
of America. It's available in the NTU audio-visual library;
here's the call number: (VC) QP306 M42z 1993 cassette 1.
And there are now online videos
of the vocals folds and of the instruments used to examine
them! Embark on a 'Fantastic Voyage' here:
https://www.youtube.com/watch?v=x_X83_EolcQ
Some people can do some pretty
remarkable things with their vocal cords. One such person is Mel Blanc (1908–1989), who provided the
voices for uncounted cartoon characters, like Porky Pig and
Tweety Bird. How does he do it? Have a look at his vocal cords
and see for yourself:
http://www.youtube.com/watch?v=ejVQEFbIfmI
And here's what the vocal cords
rock singer Steven Tyler of Aerosmith look like:
http://www.youtube.com/watch?v=B3hlooOjAxE&NR=1
Here's National Geographic's
"Incredible Human Machine", on YouTube in nine parts, in case
you'd like to see the whole thing:
http://www.youtube.com/watch?v=fXIcwm1oqQw
Some students are surprised that
the vocal folds are in fact two
flaps of flesh and not one. How do you think we would sound
with just one flap of flesh to produce voicing? And would
speech still be possible with no vocal folds at all?
Find out on the next page!
Next: Talking
with just one vocal fold, or none