Closed
captioning involves the display of subtitles superimposed over a
portion of the television picture. These subtitles or captions are
created to represent the audio portion of the television signal.
While closed captioning was initially developed for the hearing-impaired,
it can also be utilized as a teaching device by viewers for whom
English is a second language and by children, and even adults, who
are learning to read. It can even be used as a convenience device
for viewers who mute their TV to take a phone call but activate
closed captioning to continue the program dialogue.
The
captions are "closed" to the general viewing audience because television
producers believe that a continuous display of alphanumeric data
across a TV screen is distracting and bothersome to the majority
of viewers who are able to following the dialogue aurally. Any viewer
can choose to "open" the closed captioning by activating a switch
on newer television sets or utilizing a separate decoder with older
television sets that do not include the necessary decoder circuitry.
The
decoder circuitry is designed to "read" the closed captions embedded
in the vertical blanking interval. The vertical blanking interval
is that 21-line portion of the 525-line NTSC television signal which
does not contain picture information. Various lines are used to
carry technical data and one of these lines is specifically reserved
for closed captioning.
Closed
captioning is not a new idea. The concept was conceived in 1971
by engineers at the National Bureau of Standards. Further development
involved WGBH-TV, the Boston public television station, Gallaudet
University, the leading university for the hearing-impaired, and
the National Technical Institute in Rochester, New York. In 1976,
the Federal Communications Commission formerly authorized the use
of line 21, the last line of the vertical blanking interval, for
this purpose.
Closed
captioning received a major boost with the passage of the Television
Decoder Circuitry Act of 1990. This law mandated the inclusion of
closed-captioned circuitry in every television receiver with a screen
of 13 inches or more that was manufactured, assembled, imported,
or shipped in interstate commerce beginning 1 July 1993. Most receivers
sold prior to that date did not include the circuitry and viewers
who wanted to access closed captions were required to purchase a
separate decoder box for approximately $160.
The
National Captioning Institute, an independent, non-profit corporation,
worked with engineers to develop an inexpensive electronic chip
that could perform the same function as the cumbersome decoder boxes.
This chip, if included in every TV receiver, would cost as little
as $5 and this expense would presumably be absorbed into the total
production cost of the sets. Citizen groups representing the hearing-impaired
lobbied Congress to enact legislation requiring the inclusion of
a decoder chip in all receivers. Some opposition from manufacturers
groups was voiced during Congressional hearings, but the overwhelming
number of those testifying supported the legislation. The bill passed
both house and was signed into law on 15 October 1990.
Closed
captioning is program dependent and not all programs are captioned.
Most network and syndicated programs are captioned, however, and
the percentage continues to grow. Locally produced programs are
less likely to be captioned since stations lack the technical and
financial resources to provide this service. Most cities do have
one or more local newscasts with captions. Typically, the cost of
this service is underwritten by a local health care provider or
a charitable foundation.
Captions
appear in either "roll-up" or "pop-up" fashion. The captions roll
up the screen if the program is being aired live. Live captioning
is done by skilled professionals using court stenographic techniques
who can transcribe speech as rapid as 250 words per minute. The
lag time between the spoken word and the caption is one to five
seconds. The captions are not always word-for-word transcripts,
but they do closely approximate the verbal message.
"Pop-up"
captions are used for prerecorded programs and for commercials.
These captions can be prepared more leisurely and are timed to match
the flow of dialogue on the TV screen. Also, an attempt is made
to place the caption under the person speaking at the time. In a
two-person dialogue, the caption would pop-up on either the left
or right half of the screen depending on the position of the speaker.
Various icons are used to symbolize sounds; e.g., a musical note
is placed next the caption when a person is singing.
The
most challenging captions involve live sports coverage since there
is no way to anticipate what program participants will say. Newscasts
are less difficult since the same TelePrompTer that cues on-air
talent also cues the person preparing the captions.
Since
the captions are encoded as part of the electronic signal, a closed
captioned program may be transmitted in any form: over-the-air broadcast,
satellite, cable, video cassette, or video disc. Programs containing
captions are noted with a (CC) following the program title in TV
Guide and similar listings.
-Norman
Felsenthal
