What is Sound? Video Lecture | Science Olympiad Class 8

Shh cover your eyes for a moment and
just listen
what do you hear I hear my chemistry set
bubbling and speaks is that you sounds
are all around us all the time there are
so many of them and we call sounds by a
lot of different names like if the sound
is really loud and kind of unpleasant
like when there's a lot of traffic going
by we sometimes call it noise and if a
sound is made by an instrument like a
piano or a ukulele we call it a note and
we call lots of notes together music and
some words are kind of like the sounds
themselves like when fireworks go boom
popcorn pops and bells go ding-a-ling it
doesn't matter what makes a sound though
all sounds are made the same way through
vibrations when something vibrates it
moves back and forth really fast so fast
in fact that our eyes often can't see it
moving but other parts of our body can
sense vibrations and I bet you know what
parts those are that's right our ears so
how does sound get from say a bell to
our ears the air all around us is made
of tiny particles and these particles
are what carry sound we can use marbles
to demonstrate the teeny tiny particles
that make up the air let's see how if we
put a few marbles together so they're
touching then roll another marble so
that it crashes into them the group of
marbles will move that's kind of what
happens with sound when we ring a bell
we cause the metal that makes up the
bell to vibrate really fast back and
forth and the vibration of the Bell also
shakes up the particles that make up the
air around it and makes them vibrate
then those particles run into the air
particles next to them and so on you can
also think about it like dominoes with
the vibration getting passed along from
one bunch of particles in the air to the
next we call this path of vibration a
wave now how do we hear those vibrations
if we could look deep inside our ears we
see a special little part that kind of
looks like the top of a drum when sound
waves
make it all the way to and into our ears
they make this part of our ear vibrate
the vibrations keep going moving even
deeper into her ear until they finally
get to the spot that sends a message to
our brain and that message says hey
we're hearing something now who's ready
to make some vibrations we can make a
kind of musical instrument that will
help us to see the vibrations that we
make all we need is an empty can like a
coffee can and a rubber band that's just
big enough to stretch around the can
from its top to its bottom stretch the
rubber band over the top of the coffee
cans and tada we have an instrument one
that's kind of like a guitar let's pluck
the rubber band gently does it make a
sound it sure does and if we look very
very closely we can see that the rubber
band is moving back and forth when we
pull on the rubber band and let it go
we're causing it to vibrate these
vibrations travel into the air making
the air particles move through the air
to our ears in a sound wave if we pull
kind of gently the sound is kind of soft
but if we pull a little harder the sound
gets louder and if we grab the rubber
band while it's moving and stop it from
vibrating we also stop the sound hey we
made some pretty good vibrations so
whenever you hear a sound you know that
something somewhere is vibrating and
those vibrations are traveling through
the air and into your ears so thanks to
all of you who asked us how sound works
and make sure to check back every week
to learn more science with squeeks for
me and we'll see you next time