Hawking, the famous theoretical
physicist and author of "A Brief
History of Time" has been using an electronic voice synthesizer
to communicate ever since his tracheostomy following severe pneumonia.
An electronic voice synthesizer is a system implemented by software and
hardware to artificially produce speech. Stephen Hawking uses a TTS,
Text-to-Speech system that communicates his text input into
artificially derived speech. This system is one of many current
solutions created by the field of Biomedical Engineering to help
patients with speech disorders.
deos it work?
good voice produced?
What can go
wrong with it?
The human voice is
one of the most important instrument of
communication, at one moment intimate and caressing, the next
resolute. We use it for
talking, laughing, screaming, crying or for singing.
We vary the tone of voice to
plead, persuade question, or to display our emotions:
surprise, happiness or sorrow.
does it work?
To truly appreciate the intricacies of the human voice,
is helpful to
understand just how it works.
“Voice” is the sound made
vibration of the vocal folds
caused by air passing out through the larynx. The vocal
folds in combination with the teeth, the tongue, and the lips make it
to produce highly intricate arrays of sound.
The sound is produced in
the following manner:
pressure from the lungs creates a steady flow of air through the trachea (windpipe), larynx
(voice box) and pharynx (back
of the throat).
vocal folds in the larynx vibrate, creating fluctuations in air
pressure that are known as sound waves.
in the vocal tract modify these waves according to the position and
shape of the lips, jaw, tongue, soft palate, and teeth, creating
different qualities of sound.
and nose openings radiate the sound waves into the environment.
The vocal folds, also
known as vocal cords, are composed of twin infoldings of mucous
membranes stretched horizontally across the human larynx. They vibrate,
modulating the flow of air being expelled from the lungs during
folds vibrate when they are closed to obstruct the airflow through the
the space between the folds: they are forced open by increased air
the lungs, and closed again as the air rushes past the folds, lowering
principle). In singing,
vibration frequency of the vocal folds determines the
the sound produced.
or voicebox, is
cylindrical framework of cartilage bounded by ligaments and muscles
that serves to protect the trachea and anchor the vocal
folds for sound production. When
the muscles of the vocal folds contract, the airflow from the lungs is
until the vocal folds are forced apart again by the increasing air
from the lungs. This process continues in a periodic cycle that is felt
as a vibration.
How is a good voice
produce a good voice, many things must come together: there must be
in the lungs to make the vocal folds vibrate-inadequate airflow will
voice weak or strained. The layers of the vocal folds must be flexible
just the right amount of tension applied to them so that they vibrate
optimally. Vocal folds that are too tense or too lax will not vibrate
the voice will suffer. And both vocal folds must move symmetrically,
each other completely at the center of the larynx, and then vibrating
of normal vocal cord motion
video was taken using a videostroboscopy at Johns
Hopkins. Videostroboscopy is a
diagnostic tool for vocal disorders. It is a
device with a stroboscopic light and camera on the end of a probe that
vocal cord vibrations to be "freeze-framed" on a television monitor.
go wrong with the
While most normal people
take the human voice production process for granted, reduction or loss
of the ability to produce voice can disrupt or preclude normal oral
communication and thus have far-reaching social, professional, and
personal consequences. A relatively large segment of the population
suffers from voice problems: it has been estimated that anywhere from
3-9% of the general
population has some type of voice abnormality at any given moment in
production can result from a wide variety of pathological conditions;
with effects ranging from mild disturbances in vocal quality (e.g.,
slight hoarseness) to complete loss of the ability to produce laryngeal
voicing (e.g., laryngectomy to treat cancer).
Symptoms of Voice
problems occur with
a change in the voice, often described as hoarseness, roughness, or a
quality. People with voice problems often complain about or notice
pitch, loss of voice, loss of endurance, and sometimes a sharp or dull
associated with voice use. Other voice problems may accompany a change
singing ability that is most notable in the upper singing range. A more
problem is indicated by spitting up blood or when blood is present in
and Functional Disorders
individuals that have voice problems have
nothing wrong with their vocal cords. Instead, they have
referred to as "vocal misuse syndrome"-an umbrella term for an array
of behavioral and functional disorders.
causes of vocal misuse and abuse include
excessive talking, strained or excessive voice use during periods of
inflammation (e.g. allergy, infection, sinusitis, reflux), excessive
and throat clearing. Additional causes are sports requiring excessive
intrathoracic pressure (e.g. weight lifting), environmental irritants
smoke and noxious fumes, and uncoordinated or inadequate breath support
cannot solve the underlying problem in misuse
and abuse voice problems, patients with such functional voice disorders
treated with behavioral therapy.
they are also called, are a type of communication disorders where
speech is disrupted. This can mean stuttering, lisps, or hoarseness.
be caused by hearing loss, neurological disorders, brain injury, mental
retardation, drug abuse, physical impairments such as cleft lip or
vocal abuse or misuse. Many famous
people have speech disorders: they include Stephen Hawking, Thomas
James Earl Jones, Bruce Willis. They are usually treated by speech
designed by Payton Lin, 6/12/2006,
for the course BME 240