Humans
are social beings. We communicate with others using our voice as well as body
language. So it naturally becomes a problem when we lose our voice.
We
make our voice in our larynx. Here sit two ligaments called vocal cords, that
are joined together in the front and sit apart at the back, like an open “V”.
The vocal cords are covered with a soft mucosa lining, and lie horizontally
immediately above our windpipe, acting as two guards protecting our airway.
So
how do these two vocal cords make a voice? We need two things to occur for
sound to be made. First the two vocal cords are brought together by a muscle,
and at the same time, air from our lung is expelled through these closed cords.
The air passing through our cords cause the mucosa covering to vibrate, and
hence a sound (voice) is made.
The pitch of this sound, our voice, is changed
by other muscles tightening or relaxing the tension of the vocal ligaments.
When the vocal ligaments are tightened, the voice becomes higher pitched, like
when we strum a tightly stretched guitar string to create a higher note. For a
lower tone sound, the tension is reduced, and a lower, more bass voice is
produced. The voice of children, adult males and adult females also vary due to
the size of the vocal cords and the “laryngeal” box that it sits in.
A shorter vocal
cord in a smaller box as in children produce a shriller, high tone voice whilst
at the other extreme, a longer vocal cord in a bigger box of an adult male
produces a deeper voice. Here the analogy is that of a child ukulele as
compared to an adult double bass. The female adult voice is somewhere in
between. So that is how the voice is made. Speech and language which strings
sounds together to form words is different. Speech that form words of what we
want to say, in the form of phonetics as well as the tone in tonal languages
like Putonghua and Cantonese, comes from movements of our tongue above our
voice box.
So
how do we lose our voice? The commonest cause is an acute inflammation of our
larynx (acute laryngitis) e.g. when we catch the flu. The lining of the vocal
cords become swollen, inflamed and stiff and the inflammation causes pain when
we try to speak. As air passes through the cords, the vibration is impaired.
Making a sound is difficult as well as painful, and the voice changes to a very
hoarse rasp or total loss altogether.
Another
way that voice production can be impaired is if there is a growth on a vocal
cord that prevents both the vocal cords from coming together perfectly.
Conditions that could do this are e.g. cancer of the vocal cords commonly seen
in smokers. These growths tents open the gap between the cords, and allows air
to leak through the gap, making voice production inefficient at best, and
sometimes impossible at worst.
The
ultimate voice loss occurs when the vocal cords cannot come together. This is
definitely an uncommon condition. We need both vocal cords to vibrate to make a
sound. When one of the vocal cords cannot be drawn close, the gap between the
vocal cord is too wide for turbulence of the air, and therefore sound, to made
by the passing air. It is the same as when we try to whistle. We can only make
a whistle with “closed” lips and not an “open” mouth. Here the reasons why a
cord cannot “close” is usually due to damage to the nerve that supplies the
“closing” muscle of that vocal cord.
To
lose one’s voice is not unusual at all and most voices recover very quickly.
However, a persistent hoarse voice or loss of voice for more than three weeks
is not normal. If this continues, further medical attention for a diagnosis
would normally be advised.
.......cont'l
Dr Gordon Soo, The ENTific Centre
Reference: Entific.com.hk/voice-loss.html
The information aims to provide educational purpose only. Anyone reading it should consult ENT Specialists before considering treatment and should not rely on the information above.
