How It's Made

Narrator: IN THE EARLY PART OF THE 20th CENTURY,

HEADPHONES WERE USED MAINLY

BY TELEPHONE OPERATORS AND RADIO TECHNICIANS.

BUT IN THE 1930s,

THEY WERE REDESIGNED AND MARKETED TO THE PUBLIC,

SO MUSIC LOVERS EVERYWHERE PLUGGED IN

AND TURNED ON TO THE CONCEPT.

EVERYONE IS A MUSIC CRITIC,

BUT HEADPHONES ALLOW PEOPLE TO CRANK UP THE VOLUME

WITHOUT NEGATIVE FEEDBACK FROM NEIGHBORS.

TO MAKE HIGH-END HEADPHONES,

AN INJECTION-MOLDING MACHINE FIRST MAKES PLASTIC BACK COVERS.

THE MESH AREA WILL ALLOW SOUND WAVES TO PASS THROUGH

INSTEAD OF REFLECTING BACK INTO THE HEADPHONE.

DOWN THE LINE,

EQUIPMENT STAMPS TRADEMARK AND OTHER INFORMATION

ONTO TWO MORE CASING COMPONENTS --

A DECORATIVE METAL DISK, AND A PLASTIC HOUSING.

THE NEXT MACHINE WINDS COPPER WIRE

THAT'S AS THIN AS HUMAN HAIR

AROUND A CYLINDER HUNDREDS OF TIMES.

THE WINDING IS COMPUTER CONTROLLED

TO PRODUCE A CRITICAL COMPONENT --

THE HEADPHONE'S VOICE COIL.

WHEN MAGNETIZED BY AN INCOMING SIGNAL,

THE VOICE COIL VIBRATES A DIAPHRAGM,

CAUSING IT TO EMIT SOUND.

THAT DIAPHRAGM NOW TAKES SHAPE

AS A PRESS APPLIES HEAT AND PRESSURE TO A PLASTIC MEMBRANE.

THESE TOOLS MOLD THE PLASTIC TO THE DESIRED SHAPE.

THE PRESS MOLDS THE PLASTIC THICKER IN THE CENTER

AND THINNER AROUND THE OUTER ZONE

FOR A WIDE AND FLAT AUDIO-FREQUENCY RANGE.

A TECHNICIAN PUNCHES OUT THE MOLDED SHAPE.

SHE APPLIES A BEAD OF GLUE TO THE DIAPHRAGM,

THEN POSITIONS THE COPPER VOICE COIL IN AN ASSEMBLY DEVICE.

SHE ALIGNS THE GLUED SECTION OF THE DIAPHRAGM WITH THE COIL.

ULTRAVIOLET LIGHT ACTIVATES THE GLUE

TO SEAL THE COIL TO THE DIAPHRAGM.

THE PLASTIC HOUSINGS EACH CONTAIN A MAGNET.

THE NEXT TECHNICIAN INSTALLS THE DIAPHRAGM

AND VOICE-COIL ASSEMBLY ON THAT HOUSING.

THIS TAKES SKILL

BECAUSE THE COIL MUST BE POSITIONED PRECISELY

FOR THE BEST SOUND QUALITY.

AND THIS HEADPHONE SPEAKER IS NOW READY FOR AN AUDIO CHECK.

A TECHNICIAN TESTS THE AUDIO-FREQUENCY RANGE,

DISTORTION, AND OTHER FACTORS.

HERE, A TECHNICIAN JOINS THE ENDS OF CURVED WIRES

IN A PLASTIC CLIP.

THESE WIRES SERVE A DUAL FUNCTION.

THEY HOLD THE HEADPHONES SNUGLY OVER THE EARS

AND DELIVER AUDIO SIGNALS

FROM THE LEFT SIDE OF THE HEADPHONES THE RIGHT.

THE NEXT TECHNICIAN INSTALLS A CONNECTOR

FOR THE HEADPHONE'S AUDIO CABLE AND A PLASTIC STRAIN RELIEF.

AN ADJUSTABLE BAND WILL ALLOW THE HEADPHONES

TO FIT ON HEADS OF ALL SHAPES AND SIZES.

THE OPERATOR PRESSES THE PARTS TOGETHER WITH A HYDRAULIC TOOL.

MOVING DOWN THE LINE,

A TECHNICIAN NOW JOINS THE TWO HALVES OF THE SPEAKER HOUSING.

SHE FORCES THE TWO PARTS TOGETHER

WITH A PNEUMATIC TOOL...

AND FINISHES IT OFF WITH A DECORATIVE METAL RING.

SHE INSERTS THE SPEAKER MECHANISM

IN THE CENTER OF THE HOUSING,

THEN PLACES PLASTIC BRACKETS OVER IT FOR PROTECTION.

SHE THEN SECURES THE ENTIRE ASSEMBLY TO THE HOUSING.

NEXT, SHE SOLDERS TWO WIRES TO EACH HEADPHONE SPEAKER.

A PLASTIC RING AND COVER PROTECT IT

WHILE STILL ALLOWING THE WIRES TO PROTRUDE.

SHE ATTACHES THE END OF THE HEADBAND TO THE SPEAKERS...

...THEN SOLDERS THE WIRES FROM THE SPEAKER

TO THOSE PROTRUDING FROM THE HEADBAND.

SHE PRESSES A PLASTIC GRILLE INTO PLACE

OVER EACH SPEAKER VERY CAREFULLY,

TO PREVENT SCRATCHING.

THE HEADPHONES ARE NOW WIRED AND READY FOR AUDIO.

AND WHETHER IT'S ROCK OR CLASSICAL,

THE CHOICE OF MUSIC WILL BE SILENT

TO ALL BUT ONE INDIVIDUAL.

Narrator: THE DIVING REGULATOR IS A LIFELINE WHEN YOU'RE UNDERWATER.

INVENTED IN 1937,

THIS DEVICE CONVERTS COMPRESSED AIR FROM DIVING TANKS

INTO A BREATHABLE FORM

AND DELIVERS IT TO THE DIVER VIA A MOUTHPIECE.

AND THAT MEANS, ONCE YOU'VE TAKEN THE PLUNGE,

YOU CAN BREATHE EASY.

THE TWO MAIN PARTS OF A DIVING REGULATOR ARE CALLED STAGES.

COMPUTERIZED TOOLS TRANSFORM A PIECE OF BRASS

INTO THE FIRST-STAGE HOUSING.

THEY CARVE A CAVITY AND HOLES

FOR ATTACHING HOSES AND OTHER COMPONENTS.

A BLADE CUTS THE PART TO SIZE.

THEN, A DRILL CREATES A SPACE

FOR THE PRESSURE-REDUCTION VALVE.

THIS END ALSO GETS HOLES FOR MORE ATTACHMENTS.

ANOTHER TOOL SCULPTS THE SIDE TO REDUCE THE WEIGHT OF THE PART.

SLICED IN TWO,

THIS IS HOW THE FIRST-STAGE HOUSING LOOKS INSIDE.

AFTER IT'S BEEN CHROME-PLATED,

THEY INSERT PLUGS FOR THE HOLES THAT WILL LATER BE USED

FOR ATTACHING GAUGES, HOSES, AND OTHER PARTS.

THE FITTING THAT CONNECTS THE REGULATOR TO THE SCUBA TANK

GOES INTO A HOLDING DEVICE,

WHILE THE TECHNICIAN ASSEMBLES A SPECIAL VALVE

FOR KEEPING SALT WATER OUT.

HE FITS A PISTON ONTO THE END OF A SPRING,

AND THEN SLIPS THE ASSEMBLY THROUGH A HOLE

TO CONFIRM IT'S THE RIGHT SIZE.

HE INSTALLS A FILTER ON THE OTHER END OF THE SPRING.

NOW HE INSERTS THE VALVE IN THE FITTING.

HE SECURES IT WITH THIS RUBBER RING,

PRESSING IT INTO A GROOVE IN THE FITTING.

THE VALVE APPEARS TO BE FIRMLY ENTRENCHED.

HE PRESSES IT TO CONFIRM IT OPERATES CORRECTLY.

AND HE PUMPS WATER INTO A BUNCH OF THESE FITTINGS

TO CONFIRM THE VALVES INSIDE ARE, INDEED, WATERTIGHT.

HE ATTACHES A RUBBER COVER AND A CHROME-PLATED YOKE

TO THE FITTING,

THEN INSTALLS THIS ASSEMBLY IN THE HOUSING,

USING A LONG-HANDLED SOCKET WRENCH TO GET THE RIGHT TORQUE.

THIS YOKE SWIVELS TO GIVE THE DIVER SOME FLEXIBILITY

IN ATTACHING IT TO THE DIVING TANK.

HE NOW ASSEMBLES A CRUCIAL COMPONENT --

THE HIGH-PRESSURE REDUCTION VALVE.

INSTALLED INSIDE THE FIRST-STAGE HOUSING,

IT CONVERTS HIGH PRESSURE TO MEDIUM PRESSURE.

HE CAPS THE YOKE WITH A KNOB,

THEN INSERTS A PRESSURE-SENSING MECHANISM

AT ONE END OF THE FIRST-STAGE HOUSING.

HE COVERS IT WITH A RUBBER MEMBRANE.

AS THE DIVER INHALES,

THIS MEMBRANE WILL TRIGGER THE VALVE TO RELEASE MORE AIR.

THE DIVING REGULATOR'S FIRST STAGE IS NOW COMPLETE.

HE JUST NEEDS TO CALIBRATE THE PRESSURE-REDUCTION VALVE INSIDE.

HE HOOKS IT UP TO COMPRESSED AIR AND ADJUSTS THE VALVE

SO IT REDUCES AIR PRESSURE TO A PRECISE LEVEL.

HE IMMERSES IT IN WATER TO TEST FOR AIR LEAKS.

THERE ARE A FEW BUBBLES FROM PLUNGING IT UNDERWATER,

BUT NOTHING THAT WOULD INDICATE A PROBLEM.

THEY NOW MOVE ON TO THE DIVING REGULATOR'S SECOND STAGE,

WHICH WILL CONVERT THE MEDIUM-PRESSURE AIR

FROM THE FIRST STAGE TO A BREATHABLE LEVEL.

THE DIVER'S BREATHING WILL TRIGGER THIS DIAPHRAGM

TO OPEN THE AIR VALVE.

HE ATTACHED A PROTECTIVE COVER,

AND HE'S READY TO INSTALL THE SECOND-STAGE VALVE.

AFTER HE INSERTS IT IN THE SECOND-STAGE HOUSING,

THE TECHNICIAN MAKES AN INITIAL ADJUSTMENT.

THEN, USING A SPECIAL TOOL, HE PRECISELY CALIBRATES THE VALVE.

HE REMOVED THE DIAPHRAGM FOR THE LAST STEPS, SO HE REINSTALLS IT.

THEN, IT'S OVER TO A GUY WITH AN EAR FOR THE JOB.

AS AIR IS PUMPED INTO THE SECOND STAGE,

HE LISTENS FOR HISSES THAT WOULD INDICATE A LEAK.

SATISFIED THERE ARE NONE,

HE HOOKS THE REGULATOR UP TO A DEVICE

THAT SIMULATES BREATHING

AND MEASURES THE EFFORT REQUIRED TO INHALE.

IF IT CHECKS OUT, THEY LINK THE TWO STAGES WITH A HOSE,