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The S/N Ratio is
basically determined by subtracting the
average signal volume from the average
noise level. As a result, the S/N Ratio
is also measured in dBs. Most consumer
equipment have S/N Ratios of 50dB and
higher. Anything lower begins to have
noticeable noise. The S/N Ratio
will vary depending on the type of
signal you are putting into the
circuitry. A lot of professional
measurements use A-weighting.
This is measuring the S/N Ratio in
comparison to typical audio signals. It
does not take into account the S/N Ratio
of very high frequency sounds that only
dogs can hear. Impedance This is probably the
most misunderstood aspect of audio
signals. Impedance is a measure of
either an output's capability to drive
inputs or an input's capability to
receive signals from an output. It is
measured in Ohms. It is often referred
to as Z. As an example,
dynamic microphones typically have
impedances of 300ohms to 600ohms.
Condenser microphones have impedances in
the thousands. Line inputs approach
10-20kohms. Stereo
sound |
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Most humans have two
ears. If sound was recorded with two
separate microphones and played back
with two separate speakers, you could
possibly reproduce the same illusion of
left-to-right direction for sound
reproduction. This is why stereo was
created: the common implementation of
sounds recorded with two channels: left
and right. In order fake the position of
a sound somewhere in between, a
proportion of the sound is distributed
to each speaker. |
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Stereo sound doesn't
succeed in giving the illusion that the
band is right in front of you, but it
does heighten the aesthetic interest of
music or sound recorded. One real
benefit of stereo is that you can
separate the positions of different
instruments, so that each instrument can
be heard clearly while being part of a
whole mix. Stereo introduced some new terms of its own: Pan and Balance. Pan, short for panorama, dictates how much of a single sound should be given to the left speaker and how much to the right. This represents which direction in the stereo image the sound should seem to be coming from. Balance stands for how the volume of the left channel compares to that of the right channel in a stereo sound. For example, a stereo recording in which every instrument seems to be closer to the right speaker than the right has not been recorded with the correct balance (unless it was done deliberately). If you were to take a recording of a mono instrument, say, a saxophone, and put the same sound into the left and right channels of a stereo mixer, adjusting the balance of the left and right channels would actually result in you changing the pan of that single saxophone. It won't sound like two saxophones, it would just sound like a single saxophone moving from left to right as you alter the balance. Read more: |
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