1
.
-
____________________
:
when
the
direction
of
a
wave
changes
because
of
a
change
in
medium
.
2
.
-
____________________
:
a
measure
of
how
many
waves
crests
or
troughs
pass
a
given
point
in
one
unit
of
time
.
3
.
-
____________________
____________________
:
when
the
pitch
of
a
sound
changes
because
the
source
of
the
listener
is
in
motion
.
4
.
-
____________________
:
the
amount
of
time
it
takes
for
a
wave
to
complete
one
full
circle
.
5
.
-
____________________
:
the
distance
between
wave
crests
or
troughs
.
6
.
-
____________________
:
an
area
in
a
sound
wave
where
particles
of
matter
are
spread
apart
.
7
.
-
____________________
:
an
area
in
a
sound
wave
where
particles
of
matter
are
pushed
together
.
8
.
-
____________________
:
the
height
of
a
wave
from
its
trough
or
crest
to
its
midpoint
,
which
is
also
a
measure
of
the
wave's
intensity
.
9
.
-
____________________
:
how
waves
bounce
off
an
object
and
change
their
direction
of
travel
.
