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Fidelity
in recording is the same thing as fidelity in marriage. In
both cases it refers to something, or somebody, being absolutely
true. In marriage if one spouse is absolutely true to the
other, there is fidelity (loyalty or good faith). In recording
if
what you capture on tape is true to the source, then it is
what is called high fidelity.
Originally, stereo recordings were
referred to as high fidelity. It distinguished them from
older monaural recordings. Stereo
recording allowed for a sound image to be created in front
of listeners such that they could distinguish the location
of one
sound compared to another on a recording. Some sound would
appear to come from the left, some from the right and some
from the
center. This image--the result of human beings being bi-aural
(or two-eared)--seemed to approximate what people actually
heard in a concert hall compared to monaural recordings.
Hence high
fidelity. (See Haas effect.)
What high fidelity came to mean had to do with not only
the direction or placement of sound, but also how well
recording
or playback
equipment responded to the amplitude and frequency of sound.
Since there have never been perfect microphones or perfect
speakers, no sound recording or reproduction equipment has
ever been absolutely
faithful. Microphones and speakers respond to some frequencies
better than others (the reason for speakers having multiple
horns or diaphragms), either adding "presence" to
certain frequencies or failing to respond equally well to all
frequencies.
When a microphone or speaker responds to an incoming set
of sounds equally well, we say that it has a flat frequency
response. But
if you look at the frequency characteristics of any existing
mic or speaker, you will see a frequency response curve--so
called because it won't be flat. Some mics have a bass roll-off,
some
a treble roll-off, and some will add or subtract presence
at certain frequencies, usually in the middle ranges. (See
also proximity effect.)
Recordists thus have ample opportunity--provided they have
access to different microphones--to choose their mics to
meet the particular
situation or provide the desired sound in any situation.
 to Sound
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pyschoacoustics
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