along the path of the wave. Note that the highest points of the curve lie beneath the places of maximum condensation and
the lowest points of the curve are beneath places of maximum rarefaction, while points of medium density are located in
between the two extremes.
(2) Since the wave is moving to the right, the ear of the listener experiences variations of pressure identical to
those existing along the wave illustrated in figure 3. First, the rarefaction farthest to the right and then the neighboring
condensation to the left and so on. This is taking place because the entire train of waves is moving toward the ear from
the left. The graph of pressure against distance at any instant and the horizontal distance may represent intervals of time.
(3) The curve of the graph
represents sound waves set up by an
object vibrating 400 times each second.
The time required for each complete
vibration as shown in the graph is
1/400th of a second, or 2.5
milliseconds.
b. The number of complete
vibrations of the object that occur
in one second is the same as
the number of cycles of the wave in
the graph that occur in 1 second.
This number is called the frequency of
the wave. A cycle is a complete set of
FIGURE 3. Waveform of Simple Sound
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