Hands-on Science at Pasadena Public Library

AnnMarie Hurtado,LibrarianAugust 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_and_reproduction#/media/File:Emile_Berliner_with_phonograph.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+05000003))&linkText=0

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/audio/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#procedure

*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.