Hands-on Science at
Pasadena Public Library
AnnMarie Hurtado,
Librarian
August 8, 2015

*Invented by Édouard-Léon
Scott de Martinville in
France, 1857
*Sound waves were
scratched onto a cylinder
coated with soot
*Used a horn, a stylus
(needle) and diaphragm
(membrane) to pick up
vibrations and scratch
them onto the soot
http://www.recording-
history.org/HTML/musictech1.php

*It used a HUMAN EAR
from the skull of a
cadaver (dead body) to
be the diaphragm
vibrating.
*Bell attached a stylus to
this REAL HUMAN EAR
DRUM, to record sound
wave vibrations.
*The stylus wrote the
vibrations as scratches on
soot-covered glass.
http://www.mainlesson.com/display.php?
author=bachman&book=inventors&story=bell

http://www.mainlesson.com/display.php?author=bachman&book=inventors&story=bell

But I’m
betting it
didn’t smell
too good.
http://www.mainlesson.com/display.php?
author=bachman&book=inventors&story=bell

*Thomas Edison was the first
person to hear his own voice
played back to him. (Scott’s
and Bell’s phonautographs only
recorded sound visually.)
*His revised phonograph (he
revised his invention several
times!) used the same
cylinder, stylus and diaphragm
design, but tinfoil instead of
soot for a more permanent and
lasting engraving.
https://en.wikipedia.org/wiki/Phonograph#/media
/File:Edison_and_phonograph_edit1.jpg

*Turn a crank to rotate a cylinder
while talking into a mouthpiece.
The diaphragm and needle scratch
your sound waves into the tinfoil
cylinder in a spiral groove.
*Turn the crank in reverse all the
way back to the start. Replace the
stylus with something that won’t
cut, only vibrate. Now add a horn,
and this time when you turn the
crank to move the playback stylus
along the etched groove, it vibrates
the diaphragm in exactly the same
way that your voice made it vibrate
earlier. Those vibrations are
amplified by the horn so you can
hear your words.
https://en.wikipedia.org/wiki/Phonograph

*Each cylinder was expensive
and was only large enough
to record a few minutes of
sound—cylinders had to be
replaced often
*There was no way to mass-
produce the cylinders—each
cylinder was unique
*Sound quality was okay for
recording voices, but way
too poor for recording music
https://en.wikipedia.org/wiki/Phonograph

*Emil Berliner, a German
immigrant, came up with a
solution to the problems with
Edison’s invention. His
gramophone scratched sound
in a spiral groove on a rotating
disc. The disc could be flipped
over to record on the other
side. (Cylinders can only
record on one side.) Therefore
they could record longer
sounds.
*The discs were louder and had
better sound quality than
Edison’s tinfoil cylinders, so
they could record music.
http://memory.loc.gov/cgi-bin/ampage?
collId=berl&fileName=14050101//berl14050101.db
&recNum=3

*Berliner also came up with a
solution to the problem of
producing copies. Using a
process called electroplating,
which changes the surface
properties of an object using
an electrical current, Berliner
was able to create a
“negative” of a record, with a
groove that spiked out instead
of being etched in. Then he
could use that negative to
“stamp” the groove onto a
new disc.
https://en.wikipedia.org/wiki/Sound_recording_an
d_reproduction#/media/File:Emile_Berliner_with_p
honograph.jpg

*Berliner understood American
consumers and their needs a
little better than Edison did.
He knew that most people
were happy to buy a copy of a
recording made by someone
else, and didn’t feel the need
to make their own.
*For better or worse, Berliner’s
gramophone greatly reduced
the need for people to learn to
play a musical instrument,
because they could enjoy
listening to music at home just
with the turn of a crank!
http://memory.loc.gov/cgi-bin/ampage?
collId=berl&fileName=05000003//berl05000003.db
&recNum=0&itemLink=r?
ammem/berl:@field(NUMBER+@band(berl+0500000

My initial publicity said we were going to make
our own “phonograph,” but actually what we
will be making is more like a gramophone. We
will not be able to record our voices the way
that a phonograph could. But we will be able
to play the sound stored on a disc the way a
gramophone could.

*Eventually Berliner’s hand-
cranked gramophones were
replaced by motorized
electric turntables, which
not only picked up the
sound through the vibrations
of the needle, but
converted those vibrations
into an electric signal and
amplified that signal
through stereo speakers.
http://www.earbuddy.net/27329/best-albums-for-
vinyl.html/columns/a-list-obligatory

http://www.popularmechanics.com/technology/au
dio/a16081/video-record-player-needle/

*In order to play the sound
stored on a record, you will
have to spin it at a certain
speed!
*For years, different
manufacturers made their
records to play at different
speeds, though most were
played at around 78 rpm
(revolutions per minute).
*Eventually records were
developed to play at 33 1/3
rpm, for 20 minutes on each
side. These were called “long-
playing” records or LPs.
http://www.earbuddy.net/27329/best-albums-for-
vinyl.html/columns/a-list-obligatory

http://vinylgif.com/53371

http://www.sciencebuddies.org/science-fair-
projects/project_ideas/Music_p032.shtml#pro
cedure

*Over the open end of your tin can, attach a tightly-
stretched sheet of aluminum foil and secure with a
rubber band
*Tape a quilting pin to the foil so that the pin’s point
sticks out
*Get a friend to squeeze a pencil through the hole in the
center of your record so that the pointy end of the
pencil points downward toward the table or floor. This
will help you spin your record on a pointy axis.
*While your friend spins the record at 33 1/3 rpm, gently
scrape the groove of the record with the point of your
pin and try to let it be dragged by the spiraling groove.

*Remove the aluminum foil from the tin can
*Cut the skinny part off of a latex balloon so
that what’s left is wide and stretchy
*Stretch the latex over the opening of the tin
can and secure with a rubber band
*Tape a quilting pin to the latex so that the
pin’s point sticks out
*While your friend spins the record at 33 1/3
rpm, gently scrape the groove of the record
with the point of your pin and try to let it be
dragged by the spiraling groove.
*Chart the results!

*Roll a piece of paper into a cone as tight as
possible. Through the tip of the cone,
carefully insert a quilting pin and fasten it
there with tape.
*While your friend spins the record at 33 1/3
rpm, gently scrape the groove of the record
with the point of your pin and try to let it be
dragged by the spiraling groove.