>>> SOUNDS FILL OUR EARS.

TALKING, MUSIC, EVEN SOME
SCIENTIFIC EXPERIMENTS.

THEY ALL START WITH SOUND.

BUT WHAT IS SOUND?

WANT TO FIND OUT?

WE'RE HERE TO ANSWER YOUR
QUESTIONS.

STAY TUNED.

"D4K" IS NEXT.

>> HI, I'M JOAN CARTAN-HANSEN.

WELCOME TO "D4K," THE PLACE FOR
SCIENCE.

BEFORE WE GO TO YOUR QUESTIONS,
LET'S LEARN A BIT MORE ABOUT

SOUND.

SOUND IS A FORM OF ENERGY, LIKE
LIGHT OR ELECTRICITY.

SOUNDS ARE MADE BY SMALL
VIBRATIONS CALLED SOUND WAVES.

SOUND WAVES MOVE BY THE
SQUEEZING AND STRETCHING OF AIR.

WHEN A SOUND OCCURS, MOLECULES
ARE SQUEEZED TOGETHER.

ONE MOLECULE SQUEEZES INTO THE
NEXT WYNN, AND PULLED BACK IN

PLACE BY THE ONE ON THE OTHER
SIDE.

THE MOLECULES MOVE THE SOUND
ALONG IN A WAVE.

SCIENTISTS STUDY SOUND WAVES ON
A MACHINE CALLED AN

OSCILLOSCOPE.

LOUD SOUNDS HAVE MORE ENERGY.

SO THEIR WAVES ARE BIGGER AND
HAVE A GREATER HEIGHT.

SOFT SOUNDS CREATE SMALLER
WAVES.

THE HEIGHT OF A WAVE IS CALLED
ITS AMPLITUDE.

THE FREQUENCY OR NUMBER MUCH
VIBRATIONS PER SECOND,

DETERMINES A SOUND'S PITCH.

SOUND FREQUENCY IS MEASURED IN
HERTZ.

THE HIGHER THE FREQUENCY, THE
HIGHER THE PITCH, AND THE

GREATER THE HERTZ.

>> I ONLY HAVE ONE PAGE OF MATH.

>> HUMANS CAN HEAR SOUNDS
BETWEEN 20 AND 20,000 HERTZ.

BUT OTHER ANIMALS CAN HEAR EVEN
MORE.

ELEPHANTS CAN HEAR SOUNDS MUCH
LOWER THAN HUMANS CAN.

AND BATS HEAR FREQUENCIES MUCH
TOO HIGH FOR HUMANS.

BATS USE HIGH-PITCHED SOUND
WAVES LIKE RADAR TO LOCATE THEIR

FOOD.

AND JUST BECAUSE WE CAN'T HEAR
VERY HIGH AND VERY LOW FREQUENCY

SOUNDS, DOESN'T MEAN WE CAN'T
USE THEM.

SCIENTISTS TRY TO DETECT VERY
LOW INFRASONIC SOUNDS TO STUDY

POTENTIAL EARTHQUAKE AND TO
PREDICT VOLCANO ERUPTIONS.

DOCTORS USE VERY HIGH FREQUENCY
SOUNDS TO TAKE PICTURES INSIDE

THE HUMAN BODY, LIKE THESE OF A
BABY INSIDE A WOMAN'S WOMB.

SOUND WAVES EXERT PRESSURE.

THE AMOUNT OF A SOUND'S PRESSURE
OR LOUDNESS IS MEASURED IN

DECIBELS.

DECIBELS IS ALSO A MEASURE OF
INTENSITY.

THE CLOSER YOU ARE, THE STRONGER
THE FORCE.

SO SAY WERE YOU STANDING NEXT TO
LEAVES IN A LIGHT WIND.

THAT SOUND WOULD MEASURE ABOUT
10 DECIBELS.

A TOILET FLUSH IS ABOUT 67
DECIBELS.

YOUR HAIR DRYER IS ABOUT 80
DECIBELS.

AND THE SPACE SHUTTLE TAKING OFF
IS ABOUT 200 DECIBELS.

PROLONGED EXPOSURE TO SOUNDS
ABOVE 85 DECIBELS CAN DAMAGE

YOUR HEARING, SO BE SURE TO WEAR
EAR PLUGS IF YOU'RE DOING

SOMETHING AROUND LOUD SOUNDS.

AND BE SURE THE VOLUME IN YOUR
HEADPHONES IS SET AT A SAFE

LEVEL.

SOUND SURROUNDS AND DEFINES OUR
WORLD.

SO LISTEN UP, AND APPRECIATE
SOUND.

[APPLAUSE]
>> JOINING ME NOW TO ANSWER YOUR

QUESTIONS ABOUT SOUND ARE TWO
SCIENTISTS.

IN OUR POCATELLO STUDIO IS STEVE
SHROPSHIRE, PROFESSOR OF PHYSICS

AT IDAHO STATE UNIVERSITY.

THANK YOU FOR JOINING US.

>> THANK YOU FOR HAVING ME.

>> AND JOINING ME HERE IN BOISE
IS KATHRYN DEVINE, ASSISTANT

PROFESSOR OF PHYSICS AT THE
COLLEGE OF IDAHO.

LET'S GO TO YOUR QUESTIONS.

>> MY NAME IS JACK, AND I GO TO
SHADOW HILLS ELEMENTARY, AND MY

QUESTION IS, HOW ARE SOUNDS
MADE?

>> WHEN YOU MAKE A SOUND YOU'RE
ACTUALLY GETTING A LITTLE BIT OF

ENERGY TO THE AIR AROUND YOU.

AND SO SOUND IS A WAVE, A
COMPRESSION WAVE OF ALL THE MALL

CIEWLS IN THE AIR, CARRYING THAT
ENERGY FROM WHATEVER MADE THE

SOUND, MY VOICE, ALL THE WAY TO
YOUR EAR.

SO IT'S A WAVE TRAVELING THROUGH
THE AIR.

>> MY NAME IS SHELBY.

MY QUESTION IS, HOW FAST AND HOW
FAR DOES SOUND TRAVEL?

>> WELL, AT ROOM TEMPERATURE
SOUND TRAVELS AT ABOUT 330

METERS PER SECOND.

THAT'S OVER 300 YARDS EVERY
SECOND, SO IT'S QUITE FAST.

AND SOUNDS CAN TRAVEL A GREAT
DEAL OF DISTANCES.

WHEN A VOLCANO NEAR INDONESIA
EXPLODED BACK IN THE 1800s,

THE SOUND WAS HEARD FOR HUNDREDS
AND HUNDREDS OF MILES.

AND THAT'S THROUGH THE AIR.

SOUND ACTUALLY TRAVELS A LITTLE
BIT BETTER THROUGH WATER.

WE KNOW WHALES CAN COMMUNICATE
WITH EACH OTHER OVER HUNDREDS OF

MILES OF OCEAN.

>> NOAH FROM DALTON ELEMENTARY
WOULD LIKE TO KNOW, WHY DOES

SOUND TRAVEL IN WAVES?

>> WELL, A WAVE IS A DISTURBANCE
IN SOMETHING.

AND IF YOU PUSH ON SOMETHING,
LIKE A TABLE, YOU EXPECT THE

WHOLE TABLE TO MOVE.

BUT WITH AIR OR WATER, WHEN YOU
PUSH ON ONE PART OF IT, IT TAKES

A WHILE FOR THAT DISTURBANCE TO
MOVE, TO GET A BUNCH OF OTHER

STUFF.

IT'S LIKE WHEN YOU SPLASH
SOMETHING IN WATER, THROW A ROCK

IN WATER, ALL THE WATER DOESN'T
MOVE AT ONCE.

BECAUSE IT'S KIND OF FLUID.

YOU'LL HAVE A DISTURBANCE
TRAVELING OUTWARDS IN A WAVE.

WE SEE THAT IN WATER QUITE
OFTEN, AND THAT'S REALLY WHAT

HAPPENED -- WHAT IS HAPPENING IN
AIR TOO, WITH THE SOUND WE HEAR,

WE JUST DON'T SEE THE AIR MOVING
IN THE SAME WAY.

BUT IT DOES.

>> HI, MY NAME IS ALYSSA, AND I
GO TO WHITMAN ELEMENTARY SCHOOL

LEWISTON.

MY QUESTION IS, HOW DOES SOUND
TRAVEL THROUGH SPACE?

>> SOUND JUST LIKE YOU'VE JUST
SAID, WHERE YOU HAVE ONE KIND OF

PERSON PART OF THE AIR, ONE
MOLECULE COMMUNICATING THAT WAVE

TO THE NEXT ONE, THAT SAME THING
HAPPENS IN SPACE.

THE THING THAT'S DIFFERENT IS
THAT OUT IN SPACE, THE DENSITY

OF THE AIR IS A LOT LOWER, SO
THE MOLECULES ARE FARTHER APART.

AND SO SOUND CAN STILL TRAVEL IN
SPACE AS LONG AS THERE IS ANY

GAS OR MOLECULES OR ANYTHING
THERE TO COMMUNICATE F THERE

WASN'T ANYTHING THERE, SOUND
WOULDN'T BE ABLE TO TRAVEL.

SO THERE DOES HAVE TO BE A GAS
CLOUD OR SOME MOL YOU'LL OUT

THERE THAT CAN COMMUNICATE THE
ENERGY TO THE NEXT ONE.

>> MY NAME IS BRADEN, AND I GO
TO LENA IN MOSCO, IDAHO.

MY QUESTION IS, WHY DO A TRUMPET
AND A SAXOPHONE SOUND DIFFERENT,

EVEN WHEN THEY ARE PLAYING THE
SAME NOTE AT THE SAME VOLUME?

>> YOU'VE PROBABLY NOTICED
LONGER AND BIGGER INSTRUMENTS

MAKE LOWER PITCHED SOUNDS, LOWER
NOTES, AND SHORTER AND SMALLER

INSTRUMENTS MAKE HIGHER PITCHED
SOUNDS.

THAT HAS TO DO WITH HOW THE
SOUND RESONATES IN THESE

DIFFERENT INSTRUMENTS.

TO ILLUSTRATE I HAVE SOME LITTLE
PIPES HERE.

AND THIS ONE IS CUT A LITTLE
LONGER THAN THE OTHERS, AND WHEN

I WHACK IT ON MY PALM, I GET A C
NOTE.

AND WITH THE BLACK ONE, THAT'S A
D, ORANGE ONE, E, F, G, AND AN

A.

YOU CAN SEE THE SHORTER THE PIPE
THE HIGHER THE PITCH.

I'VE GOT SOMETHING YOU CAN DO AT
HOME WITH A LITTLE PLASTIC

STRAW.

IF YOU TAKE A STRAW AND YOU CUT
LITTLE GROOVES IN IT, SHAPED

LIKE TRIANGLES, LIKE I HAVE
HERE, AND YOU BITE IT DOWN WITH

YOUR TEETH, YOU CAN MAKE A
LITTLE REED.

A LOT OF INSTRUMENTS WORK ON
REEDS.

WHEN YOU BLOW AIR BETWEEN THE
REEDS, THEY VIBRATE.

AND THE LONGER THE INSTRUMENT,
THE LOWER THE PITCH OF SOUND

WILL RESONATE IN THAT.

AND SO IF I JUST BLOW ON THIS
STRAW, WE GET A NOTE, AND IF I

TAKE TWO STRAW AND STICK THEM
TOGETHER, I'LL GET A LOWER

PITCH.

AND I CAN EVEN CHANGE THE LENGTH
OF THE PIPE AND GET DIFFERENT

PITCHES FROM THE SAME STRAW.

*
>> THAT'S GREAT.

[LAUGHTER]
OK.

LET'S GO BACK TO THE QUESTIONS.

>> HI, MY NAME IS SARAH, I GO TO
ST. MARY'S ELEMENTARY, AND MY

QUESTION IS, WHY -- HOW DOES
SOUND TRAVEL BETTER THROUGH

WATER?

>> WELL, WATER IS DENSER.

THERE'S MORE STUFF THERE IN A
SMALLER SPACE, AND THE MOLECULES

ARE CLOSER TOGETHER, AND SO WHEN
SOME MOLECULES GET THE ENERGY

FROM THE SOUND, FROM THE
DISTURBANCE, THEY WILL COLLIDE

WITH OTHER MOLECULES SOONER, AND
MORE RAPIDLY.

AND ALSO WATER IS A LITTLE MORE
ELASTIC THAN AIR, AND YOU CAN

THINK OF IT AS BEING STIFFER IN
A WAY.

AND ALL THAT CONTRIBUTES TO
MAKING THE SOUND TRAVEL BETTER

AND FARTHER.

>> ONE OF THE THINGS I'VE ALWAYS
FOUND INTERESTING, I DON'T KNOW

ABOUT THE AUDIENCE OUT THERE,
BUT I ALWAYS TRIED TO TALK TO MY

BROTHER UNDER WATER WHEN WE WERE
KIDS.

IT WOULD ALWAYS SOUND WEIRD.

THAT'S BECAUSE WATER TRANSMITS
DIFFERENT FREQUENCIES AT

DIFFERENT SPEEDS, SO OUR EARS
ARE USED TO HEARING SOUNDS IN

AIR.

BUT EVEN THOUGH WATER CAN
TRANSMIT SOUNDS FASTER BETTER,

IT DOESN'T TRANSMIT IT IN A WAY
OUR EARS ARE USED TO HEARING,

WHICH IS WHY IT SOUNDS GAR
ABOUTED.

>> IS THERE AN OBJECT SO THICK
OR SO STRONG THAT SOUND CAN'T

PASS THROUGH IT?

>> IT KIND OF DEPENDS, I GUESS,
ON HOW YOU THINK ABOUT IT.

SOUND IS ENERGY TRAVELING, IT'S
AN ENERGY WAVE, SO THE LOUDER

THE SOUND, THE MORE ENERGY
YOU'RE PUTTING IN, THE THICKER

SOMETHING WOULD HAVE TO BE TO
STOP THE ENERGY FROM TRAVELING

THROUGH IT.

AND SO, FOR EXAMPLE, IF I WAS
WHISPERING AND YOU HAD JUST A

WALL, THAT WOULD BE ENOUGH TO
STOP THE SOUND FROM TRAVELING

THROUGH IT.

BUT IF I WAS SHOUTING, MAYBE A
WALL WOULDN'T BE ENOUGH AND IT

WOULD HAVE TO BE THICKER.

IT DEPENDS ON HOW LOUD THE SOUND
IS OR HOW THICK SOMETHING WOULD

HAVE TO BE TO BLOCK THE SOUND.

>> HI, MY NAME IS SEAN, AND I'M
FROM ILLINOIS.

MY QUESTION IS, HOW FAR CAN THE
FIRE ALARM SOUND POSSIBLY

TRAVEL?

>> DEPENDS ON THE FIRE ALARM AND
IT DEPENDS ON WHAT'S IN THE WAY

OF THE FIRE ALARM.

AGAIN, THE THINGS THAT CAN MAKE
SOUND TRAVEL FARTHER IS THE

AMOUNT OF ENERGY THAT IS BEING
PRODUCED OR THAT THE SOUND IS

GIVING OUT.

AND SO IF YOU -- IT DEPENDS ON
THE VOLUME OF YOUR FIRE ALARM

AND THE FIRE ALARM.

SOMETIMES BIG APARTMENT
BUILDINGS HAVE VERY HIGH ENERGY

LOUD FIRE ALARMS, LIKE IN A
SCHOOL BUILDING BECAUSE THEY

HAVE TO BE ABLE TO HEARD TROUT
THE WHOLE BUILDING, VERSUS THE

FIRE ALARM IN MY BEDROOM ISN'T
AS LOUD, IT PRODUCES LESS

ENERGY.

SO YOU WOULDN'T BE ABLE TO HEAR
IT PROBABLY AS FAR AS MY

NEIGHBOR'S HOUSE.

BUT IF A FIRE ALARM IN A BIG
BUILDING GOES OFF YOU CAN HEAR

IT FARTHER AWAY.

IT COMES DOWN TO HOW MUCH ENERGY
THE SOUND IS GIVING OFF, HOW

MUCH ENERGY IS GOING ON AT THE
SOURCE.

>> DID YOU KNOW THAT DOLPHINS ON
COULD HEAR SOUNDS UNDER WATER

FROM 15 MILES AWAY?

SNAKES ON THE OTHER HAND HAVE NO
EARS.

THEY SENSE SOUND WITH THEIR
TONGUES.

CAMERON AT DOLL TON ELEMENTARY
WOULD LIKE TO KNOW, HOW MANY

ANIMALS USE SOUND TO NAVIGATE
THEIR WAY AROUND THE WORLD?

>> LOTS OF THEM.

WE KNOW THAT BATS USE SOUND TO
NAVIGATE, AND TO HUNT.

THEY ACTUALLY LISTEN VERY
CLOSELY TO THE SOUND, THE ECHOS

OF THE SOUND THAT BOUNCE OFF OF
THE INSECTS AND OBJECTS AROUND

THEM.

ALSO A LOT OF THINGS THAT LIVE
IN WATER.

SINCE SOUND TRAVELS SO WELL
THROUGH WATER, A LOT OF FISH AND

OCEAN CREATURES USE SOUND TO
NAVIGATE, AND ALSO TO HUNT.

AND THERE'S EVEN SOME BIRDS
THAT DO THAT TOO.

>> MA TILDA, ALSO FROM DALTON
GARDENS ELEMENTARY WOULD LIKE TO

KNOW, WHY CAN'T YOU SEE SOUND
WAVES?

>> SO A SOUND WAVE IS A LITTLE
TINY MOLECULE THAT YOU CAN'T

SEE.

SO I GUESS IT GOES DOWN TO THE
FACT YOU CAN'T SEE THE AIR, EVEN

THOUGH THERE IS STUFF IN THE AIR
BETWEEN US, YOU CAN'T SEE IT.

THERE'S NOTHING THAT I CAN SEE
HERE.

BUT THAT'S THIS AIR IN FRONT OF
ME IS WHAT IS MAKING THE SOUND

WAVE PROPAGATE THROUGH.

I SUPPOSE IF YOU HAD AMAZING
EYES AND COULD SEE THE MOLECULES

MOVING, YOU WOULD BE ABLE TO SEE
THE SOUND WAVE, BUT WE CAN'T

ACTUALLY SEE THE SMALL, SMALL
THINGS IN THE AIR THAT ARE

TRANSMITTING THE SOUND WAVE
ALONG THE AIR.

>> IF I COULD JUMP IN, THERE
IS -- IF YOU EVER WATCHED

EXPLOSIONS, OR VERY, VERY LOUD
NOISES, YOU SEE IT A LOT WITH

ARTILLERY, SAY WITH THE ARMY.

YOU CAN ACTUALLY SEE WHAT LOOKS
LIKE A SOUND WAVE, BUT WHAT

YOU'RE SEEING IS YOU HAVE SO
MUCH ENERGY BEING DEPOSITED IN

THE AIR, THE WATER IN THE AIR
CONDENSES OUT INTO LITTLE WATER

DROP LET'S, AND YOU'LL ACTUALLY
SEE WHAT LOOKS LIKE A WAVE

TRAVELING THROUGH THE AIR, BUT
IT'S REALLY THE WATER CONDENSING

OUT BRIEFLY AS THE SOUND WAVE
GOES THROUGH IT.

SO YOU'RE NOT ACTUALLY SEEING
THE AIR, BUT YOU'RE SEEING WATER

THAT'S BEING IN A WAY DRIVEN OUT
OF THE AIR BRIEFLY BY THE

INTENSE SOUND.

>> HI, MY NAME IS ANNE.

MY QUESTION IS, HOW FAST DO YOU
HAVE TO GO TO BREAK THE SOUND

BARRIER?

>> THE SPEED OF SOUND IS 330
METERS PER SECOND.

HERE AT ROOM TEMPERATURE.

SO THAT'S ABOUT HOW FAST YOU'D
HAVE TO GO.

ABOUT 330 YARDS EVERY SECOND.

>> HI.

MY NAME IS McKENNA, I GO TO
RUSSELL SCHOOL IN MOSCO.

MY QUESTION IS, WHY IS THE SPEED
OF LIGHT FASTER THAN THE SPEED

OF SOUND?

>> THAT'S ACTUALLY A REALLY
INTERESTING QUESTION.

LIGHT WAVES AND SOUND WAVES ARE
A PRETTY DIFFERENT AND VERY

FUNDAMENTAL WAY.

SO SOUND WAVES REQUIRE THAT YOU
HAVE AIR OR GAS OR SOMETHING

THAT WILL TRANSMIT, SOME
MOLECULE THAT WILL TRANSMIT THE

WAVE, BECAUSE THEY HAVE TO PASS
THE SIGNAL TO THE NEXT MOLECULE

TO PASS THE WAVE ALONG.

LIGHT, ON THE OTHER HAND, IF YOU
HAD A VACUUM WHICH IS A TOTAL

ABSENCE OF ANYTHING, TOTALLY
EMPTY SPACE, YOU CAN STILL HAVE

A LIGHT WAVE TRAVEL THROUGH IT
BECAUSE LIGHTS -- LIGHT TRAVELS

THROUGH A FIELD, IT DOESN'T
REQUIRE HAVING MOLECULES.

SO KIND OF OFF TOPIC, BUT
THEY'RE VERY DIFFERENT AND VERY

INTERESTING.

THE SPEED THEN SINCE LIGHT
DOESN'T DEPEND ON MOLECULES

COMPRESSING INTO EACH OTHER TO
TRANSMIT THE WAVE ALONG, THEY

CAN TRAVEL FASTER, SO IT HAS TO
DO WITH HOW THE

WAVE -- PROPAGATES THROUGH
SPACE.

SO IT JUST A VERY DIFFERENT WAY
OF HAVING THE ENERGY TRAVEL

THROUGH SPACE THAT MAKES IT SO
LIGHT CAN GO FASTER.

>> JACK FROM DALTON ELEMENTARY
WOULD LIKE TO KNOW, HOW DOES

YOUR VOICE ECHO?

>> YOUR VOICE ECHOS WHEN THE
SOUND BOUNCES OFF OF SOMETHING

ELSE.

IT'S BASICALLY A REFLECTION OF
THE SOUND.

AGAIN, USING THE ANALOGY OF
THROWING A ROCK INTO WATER, IF

YOU'VE GOT LIKE A STIFF BANK, A
CONCRETE POND, YOU'LL SEAT WATER

RIPPLES HITTING THE EDGE OF THE
POUND EVER POND AND BREAKING

BACK.

THE SAME THINGS HAPPEN WITH YOUR
ECHO, AND YOU CAN HEAR THE SOUND

BOUNCING OFF OF SOMETHING.

SO IT'S LIKE THE SOUND WAVE IS
MOVING AND HITS SOMETHING AND

BOUNCES RIGHT BACK TOWARDS YOU.

SO YOU CAN HEAR YOUR OWN VOICE
AGAIN.

OR OTHER SOUNDS, TOO.

SO IT'S BASICALLY A BOUNCING OFF
THE SOUND OFF SOMETHING ELSE.

>> MY NAME IS ALYSSA, HOW DOES
SOUND TRAVEL TO iPOD TO

HEADPHONES?

>> IT'S NOT SOUND TRAVELING
THROUGH THE CORD, IT'S BASICALLY

AN ELECTRICAL SIGNAL.

AND THE ELECTRICAL SIGNAL GOES
TO A SPEAKER, AND THE ENERGY OF

THE ELECTRICITY MAKES A LITTLE
MEMBRANE THERE VIBRATE.

AND SOMETHING VIBRATES, IT WILL
MOVE THE AIR AROUND IT.

SO THE SOUND IS ONLY EXISTS
THERE AT THE SPEAKER INSIDE YOUR

EAR.

IT DOESN'T EXIST INSIDE THE
CORD.

THAT'S ELECTRICITY.

IT CARRIES THAT INFORMATION THAT
BASICALLY MAKES THE SPEAKER

MOVE.

>> A LOT OF YOU HAD QUESTIONS
ABOUT SOUND AND HEARING.

SO LET'S LEARN A LITTLE BIT MORE
ABOUT HOW OUR EARS AND BRAINS

HEAR SOUND.

>> WHEN YOU MAKE A SOUND, YOU
CREATE ENERGY IN THE FORM OF

SOUND WAVES.

A LOUD SOUND HAS TALLER WAVES
THAN A SOFT ONE.

THESE WAVES EVENTUALLY ENTER
YOUR EARS.

THE SOUND WAVES TRAVEL DOWN THE
EAR CANAL.

THE EAR CAN AM IS ABOUT AN INCH
LONG, AND AT ITS END IS A THIN

PIECE OF SKIN CALLED THE
EARDRUM.

THE EARDRUM IS STRETCHED TIGHT,
JUST LIKE THE TOP OF A DRUM.

WHEN THE SOUND WAVES HIT THE
EARDRUM, IT BEGINS TO VIBRATE.

THAT VIBRATION MAKES THREE TINY
BONES IN YOUR MIDDLE EAR BEGIN

TO MOVE.

THESE THREE LITTLE BONES ARE
KNOWN AS THE HAMMER, ANVIL, AND

STIR UP, BECAUSE THAT'S WHAT
THEY KIND OF LOOK LIKE.

THEY FEEL THE BONES TRANSMIT OR
MOVE THE SOUND WAVES ALONG TO

THE INBOUNDER EAR.

THEY ALSO INCREASE THE FORCE OF
SOUND WAVES.

THEY MOVE INTO A SNAIL SHAPED
STRUCTURE CALLED THE COKE LEE A.

THEY'RE FILLED WITH FLUID AND
17,000 HAIRLIKE TISSUES.

SOUND WAVES MOVE THROUGH THE
FLUID AND THE HAIR BENDS.

SOMEHOW THE MOVEMENT OF THOSE
HAIRS STIMULATES THE 30,000

NERVE FIBERS.

THAT NERVE CARRIES THE SIGNAL TO
THE BRAIN AND THE BRAIN FIGURES

OUT WHAT THE SOUND IS.

YOU NEED TWO EARS TO FIGURE OUT
WHERE A SOUND COMES FROM.

YOUR BRAIN FIGURES THE TERRENCE
BETWEEN THE TWO SOUND LEVELS,

AND CALCULATES THE DIRECTION OF
THE SOUND.

IT'S IMPORTANT TO PROTECT YOUR
HEARING FROM LOUD SOUNDS.

MUSCLES IN THE MIDDLE EAR
PROTECT THE EAR BY STIFFENING

THE EARDRUM, OR BY MOVING THE
STIR UP BONE AWAY FROM THE INNER

EAR.

BUT SUDDEN LOUD SOUNDS CAN BREAK
THE EARDRUM OR CAUSE OTHER

DAMAGE AND CONTINUED LOUD SOUNDS
CAN DAMAGE THE TINY HAIRS IN THE

COCHLEA.

BE SURE TO WEAR HEARING
PROTECTION IF YOU'RE GOING TO BE

AROUND LOUD NOISES, AND TURN THE
VOLUME DOWN ON YOUR HEADPHONES.

BECAUSE ONCE YOUR HEARING IS
DAMAGE THE, IT CAN'T BE MADE ALL

BETTER.

ABOUT 200,000 AMERICANS ARE
DEAF.

THAT MEANS THEY CAN'T HEAR
ANYTHING.

ANOTHER 3 MILLION HAVE SEVERE
HEARING PROBLEMS.

SOME USE HEARING AIDS TO AMPLIFY
OR INCREASE THE STRENGTH OF

SOUND WAVES SO THEY CAN HEAR
BETTER.

OTHERS HAVE A COCHLEAR IMPLANT.

THAT'S WHERE A SMALL MICROPHONE
HELPS TRANSMIT SOUND TO THE

INNER EAR.

INDIVIDUALS WHO ARE DEAF OR HARD
OF HEARING SOMETIMES USE SIGN

LANGUAGE TO COMMUNICATE.

OTHERS CAN READ LIPS.

COMMUNICATING, WHETHER IT'S WITH
YOUR EARS OR YOUR HANDS, IS

ESSENTIAL TO LIFE.

BY THE WAY, YOUR EAR DOES ONE
OTHER THING -- REMEMBER THE

COCHLEA?

MOVEMENT OF THE FLUID INSIDE
THAT TELLS THE BRAIN ABOUT YOUR

BODY POSITION.

THAT WAY YOU CAN TELL UP FROM
DOWN, EVEN WITH YOUR EYES

CLOSED.

WHEN YOU SPIN AROUND, THE FLUID
IN THE COCHLEA SPINS TOO, AND

THAT EXPLAINS WHY YOU FEEL
DIZZY.

>> HI, MY NAME IS JOY, I GO TO
WHITMAN ELEMENTARY SCHOOL.

MY QUESTION IS, HOW DO YOU HEAR
SOUNDS IN YOUR EARS?

>> OK.

SO YOUR EARS I THINK YOU HAVE
PROBABLY NOTICED, YOUR EARS HAVE

A LITTLE HOLE IN THEM, THERE'S A
LITTLE ENTRANCE THERE.

SO THE SOUND WAVES COME IN AND
THEY HIT THAT ENTRANCE TO YOUR

EAR, AND THEN WHAT -- YOU HAVE
LITTLE HAIRS IN YOUR EAR THAT

RESPOND TO THE WAVES, SO JUST
KIND OF LIKE SEAWEED IN A POND

THAT'S GETTING MOVED AROUND BY
THE WAVES IN THE WATER, THE

SOUND WAVE MOVES THESE LITTLE
DETECTORS IN YOUR EAR AROUND,

AND THOSE TRANSMIT A SIGNAL TO
THE NERVOUS SYSTEM THAT

EVENTUALLY COMMUNICATES THAT
INFORMATION TO YOUR BRAIN AND

TELLS YOU WHAT KIND OF SOUND
YOU'RE HEARING.

>> MY NAME IS KENDALL, I GO TO
CAMELOT ELEMENTARY, AND MY

QUESTION IS, WHY DO LOUD NOISES
HURT OUR EARS?

>> AGAIN, WITH THE LITTLE HAIRS
IN YOUR EARS, A LOUD SOUND, THAT

WOULD BE LIKE A WAVE THAT'S TOO
BIG IN THE EXPOND SMASHES ALL

THE SEAWEED DOWN.

SO IF YOU HAVE A WAVE THAT'S TOO
MUCH ENERGY COMING TO YOUR EAR,

IT CAN HURT ALL THOSE LITTLE
DETECTORS BECAUSE THEY'RE NOT

CLIPPED, ARE -- THEY'RE NOT
EQUIPPED OR THEY'RE NOT READY

FOR ALL THAT ENERGY.

IT CAN ACTUALLY HURT THE
DETECTORS IN YOUR EAR, AND THEN

IF YOU HAVE EVER HEARD A REALLY
LOUD NOISE THAT CAUSES RINGING

IN YOUR EAR, THE INABILITY TO
HEAR AS WELL THAN BEFORE YOU

HEARD THE LOUD NOISE, IT'S
BECAUSE YOU DAMAGED THE

DETECTORS IN YOUR EAR.

>> HANNAH WOULD LIKE TO KNOW IF
THERE'S A CLASSROOM FULL OF KIDS

AND THE TEACHER WAS SPEAKING,
WOULD THE KIDS ALL HEAR THE

SOUND AT THE SAME TIME?

>> NO.

THEY WOULDN'T.

BUT IN A CLASSROOM, IT'S ENOUGH
SPACE SO THAT AGAIN, SOUND

TRAVELS AT ABOUT 330 METERS PER
SECOND, THE TYPICAL CLASSROOM IS

ONLY MAYBE A DOZEN METERS, MAYBE
AT MOST 15 METERS LONG.

AND SO YOU'RE TALKING ABOUT TINY
FRACTIONS OF A SECOND DIFFERENCE

BETWEEN WHEN SOMEONE CLOSE TO
THE TEACHER CAN HEAR AND SOMEONE

FAR AWAY.

IF YOU WANT TO BE VERY PICKY,
YES, THEY'LL HEAR IT AT

DIFFERENT TIMES, BUT IT WILL BE
SO QUICK, NO ONE REALLY WILL

NOTICE.

>> YOU COULD NOTICE IT IF YOU
WERE IN A MUCH LARGER SPACE.

SO YOU'VE PROBABLY SEEN THIS
WHEN YOU'VE WATCHED FIREWORKS,

WHERE FIREWORKS, IF YOU'RE VERY
CLOSE TO WHERE THE FIREWORKS ARE

GOING OFF YOU SEE THE EXPLOSION
AT THE SAME TIME YOU HEAR THE

BOOM.

IF YOU'RE FARTHER AWAY, AGAIN,
YOU THAN GET SEVERAL HUNDRED

FEET AWAY FROM THE FIREWORKS AND
STILL BE ABLE TO SEE THEM, THE

PEOPLE CLOSER TO THE FIREWORKS
ARE HEARING THEM SOONER THAN YOU

ARE.

THAT'S HOW YOU GET THAT LAG
BETWEEN WHEN YOU SEE THEM AND

WHEN YOU HEAR THE EXPLOSION.

IT COULD BE OVER A LARGE
DISTANCES TO NOTICE THAT EFFECT.

>> GABE WOULD LIKE TO KNOW, WHAT
IS ULTRASOUND?

>> SO ULTRASOUND IS SOMETHING
THAT I THINK A LOT OF PEOPLE

HEAR ABOUT IN MEDICINE IN TERMS
OF BEING ABLE TO GET AN

ULTRASOUND IMAGE.

THAT'S THE TECHNIQUE OF USING
SOUND, SINCE SOUND WAVES TRAVEL

THROUGH MEDIUM, TO USE SOUND TO
BOUNCE OFF AN OBJECT LIKE INSIDE

THE HUMAN BODY, SO YOU CAN PUT
AN ULTRASOUND MACHINE ON SOME OF

THESE ABDOMEN AND SEE THEM
INSIDE THEM BECAUSE THE SOUND

WAVES COMES THROUGH, INTERACT
WITH SOMETHING DENSER THAN

SOMETHING IN THE REST OF THE
BODY AND REFLECTS BACK OUT AND

SO THEN THE DETECTOR CAN USE
THOSE IMAGES TO MAKE A PICTURE.

>> ELLIE WOULD LIKE TO KNOW HOW
FAR CAN SOUND TRAVEL?

>> THIS DEPENDS ON HOW LOUD THE
ORIGINAL SOUND WAS.

SO THE MORE ENERGY THAT GOES
INTO THE ORIGINAL SOUND, THE

FARTHER IT CAN TRAVEL.

AND SO IF YOU HAVE LIKE A
WHISPER YOU MIGHT NOT BE ABLE TO

HEAR THAT MORE THAN A FEW FEET
AWAY, BUT IF YOU HAVE A LOUD

VOLCANO EXPLODING WITH A LOT OF
ENERGY YOU MIGHT BE ABLE TO HEAR

THAT HUNDREDS OF MILES AWAY.

>> HI.

MY NAME IS CASSIDY, AND I GO TO
WEST PARK ELEMENTARY SCHOOL IN

MOSCOW.

THIS IS MY QUESTION -- ARE THERE
SOFT SOUNDS YOU CAN'T HEAR?

>> OH, YES.

AGAIN, WE HAVE TO HAVE A CERTAIN
AMOUNT OF ENERGY COMING INTO OUR

EARS TO MOVE OUR LITTLE CILIA
AROUND ENOUGH FOR US TO DETECT

THE SOUND.

THERE ARE VERY, VERY FAINT
SOUNDS WE CAN'T HEAR.

IT'S LIKE INSECTS STRACHG
THEMSELVES.

WE'VE BEEN ABLE TO PICK UP THAT
SOUND WITH SENSITIVE

MICROPHONES, BUT NO MATTER HOW
HARD YOU LISTEN I DON'T THINK

YOU CAN HEAR A BUG SCRATCHING
ITS BACK.

>> LET ME ASK A COUPLE OTHER
QUESTIONS.

WHY DID YOU GUYS DECIDE TO STUDY
PHYSICS AND THEREFORE STUDY

ABOUT SOUND?

>> SO WHEN I WAS IN COLLEGE, I
REALLY LIKED MATH.

I WAS GOOD AT MATH, AND I REALLY
LIKED SCIENCE, BUT DIDN'T KNOW

WHAT AREA I WANTED TO GO INTO.

SO MY FIRST YEAR OF COLLEGE I
STARTED WORKING, I TOOK A

PHYSICS CLASS AND REALIZED THAT
THAT WAS THE PERFECT COMBINATION

OF BEING ABLE TO USE MY MATH
SKILLS AND THEN SCIENCE, AND I

STARTED WORKING FOR A PROFESSOR
WHO DID ASTRONOMY, WHICH WAS THE

COOLEST THING TO ME AT THE TIME.

SO THEN I WAS ABLE TO COMBINE
MATH, PHYSICS, AND ASTRONOMY

INTO THE SAME LIFE TRAJECTORY.

SO THAT'S BEEN GREAT.

>> STEVE?

>> WELL, I HAD A VERY GOOD HIGH
SCHOOL PHYSICS TEECHER, AND HE

INSPIRED ME, AND HE STRONGLY
INFLUENCED MY CHOICE OF CAREER

AND STUDY, BUT PHYSICS AND
SCIENCE IN GENERAL, I LIKE THE

IDEA OF BEING ABLE TO FIGURE OUT
HOW THINGS WORK.

HOW THE UNIVERSE WORKS.

WE LIVE IN A WONDEROUS PLACE,
AND LEARNING MORE ABOUT IT IS

JUST FASCINATING.

AND SCIENCE SEEMED TO ME AND
STILL DOES THE BEST WAY TO GO

ABOUT LEARNING MORE ABOUT THE
WORLD AROUND US.

>> STEVE, IF A STUDENT WANTS TO
BECOME A PHYSICIST AND STUDY

SOUND, WHAT SHOULD THEY DO WHEN
THEY GET TO SCHOOL, WHAT CLASSES

SHOULD THEY TAKE?

>> OH, SCIENCE.

SCIENCE AND MATHEMATICS.

MATHEMATICS IS THE LANGUAGE OF
WHICH SCIENCE IS SPOKEN.

SO YOU NEED TO BE FAIRLY FLUENT
WITH MATH IN ORDER TO DO

SCIENCE.

BUT I WOULD SAY SAMPLE AS MANY
SCIENCE CLASSES AS YOU CAN, AND

GO WITH WHAT YOU FIND
INTERESTING.

WHAT FASCINATES YOU.

>> WOULD I AGREE WITH THAT TOO.

THE MATHEMATICS IS IMPORTANT
BECAUSE IT HELPS YOU KIND OF,

AGAIN, SPEAK THE LANGUAGE OF THE
SCIENCES.

WHEN I STARTED TAKING SCIENCE I
TOOK BIOLOGY AND CHEMISTRY, AND

GEOLOGY, PHYSICS, AND THEY'RE
ALL -- THEY ALL GET USED

TOGETHER, THERE'S NOT CLEARLY
SEPARATED OUT FIELDS IN

ASTRONOMY, THERE'S A LOT OF
CHEMISTRY AND IN PHYSICS THERE'S

BIOLOGY.

SO I WOULD HAVE TO AGREE WITH
STEVE, TAKE AS MUCH SCIENCE AS

YOU CAN SO YOU CAN FIND THE
THING YOU'RE REAL LIQUEURUS

ABOUT AND WANT TO KEEP ASKING
QUESTIONS ABOUT.

>> I'M SORRY WE'VE RUN OUT OF
TIME.

I THANK STEVE SHROPSHIRE AND
KATHRYN DEVINE FOR ANSWERING OUR

QUESTIONS.

THANKS, STEVE.

>> THANK YOU.

>> THANKS, KATHRYN.

>> THANKS SO MUCH FOR HAVING US.

>> YOU CAN LEARN LOTS MORE ABOUT
SOUNDS AND OTHER TOPICS ON THE

"D4K" WEBSITE AND WE'LL ANSWER
MORE QUESTIONS ABOUT SOUND IN

THE "D4K" WEB ONLY.

YOU'LL FIND IT ALL AT
IDAHOPTV.ORG/D4K.

OUR LATEST WINNER IN OUR
QUESTION CONTEST IS TAYLOR AT

MRS. HUNT'S CLASS AT CYNTHIA
MANN ELEMENTARY IN BOISE.

REMEMBER, WHEN YOU SEND IN A
QUESTION, YOU AND YOUR CLASS ARE

ELIGIBLE FOR OUR CONTEST.

CHECK OUT THE CONTACT US PART OF
THE "D4K" WEBSITE FOR SHOW

DEADLINES AND HOW TO SUBMIT YOUR
I'M AND VIDEO QUESTIONS.

AND CHECK OUT MY SCIENCE BLOG
FOR THE LATEST SCIENCE NEWS FOR

KIDS.

IDAHOPTV.ORG.

THANKS FOR JOINING US.

WE'LL SEE YOU NEXT TIME ON
"D4K."

Captioning Performed By
LNS Captioning
www.LNScaptioning.com

>> DO YOU HAVE A SCIENCEQUESTION?

>> YEAH!

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PRIZES?

>> YEAH!

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TO USE ON "D4K," YOU AND YOUR

CLASS ARE ELIGIBLE TO WIN DVDs
AND OTHER PRIZES.

CHECK OUT THE "D4K" WEBSITE FOR
THIS SEASON'S TOPICS AND SEND IN

YOUR QUESTIONS.

YOU CAN SEND US AN EMAIL OR
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RECORD OUT YOUR WEBCAM OR CELL
PHONE.

IF YOU'RE AN EDUCATOR WE'LL EVEN
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FIND OUT ALL THE DETAILS ON HOW
TO ?END YOUR QUESTION AND WIN ON

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ABOUT THIS TOPIC OR WATCH OUR

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