# the tin can phone article on the wikipedia is wrong.

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I examined the articles and videos about 'the tin can phone'. I concluded that all the articles and youtube videos about it are fake.

But now let's understand why the tin can phone articles are bullshit. Let's examine wikipedias article en.wikipedia.org/wiki/Tin_can_telephone    Basically they begin their

article saying it works, without providing any technical prove. The whole article is anti-scientific bullshit.

They say: "When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a diaphragm, converting the

sound waves into longitudinal mechanical vibrations which vary the tension of the string. " . In this quote, they deliberately and criminally omit what the

material the string is made of, nor they point out the shape of the "cans". The waves on the string are not longitudinal. They insolently lie that the sound from those cans can travel by a ... textile rope. They lie that it can travel if that textile rope is twisted. Absolutely idiotic. Horrifying! Also, the sound waves reflect off the solid

surfaces!

To confirm this, i read some articles and found the formula.

It is called  Reflection coefficient. (there is also the transmission coefficient formula but I think it is not needed here).

You cannot simply transmit sound from air to metal because of impedance mismatch.
R=reflection coefficient and it is supposed to show how much sound reflects.

[formula image]

where p=density

c=speed of sound

z=impedance

since z=p*c, then
R=(z2-z1)/(z1+z2)
where z is impedance for longitudinal. z=density * speed

Zair=1.29 kg/m3 * 343 m/s = 442

Zsteel(the tin cans are made of steel)=7800 kg/m3 * 5790 m/s=45162000

Zwater=1000 kg/m3 * 1493 m/s=1493000

[airwater]

Reflection coefficient , water and air = 99.9% of sound is reflected.

[steelair]

Reflection coefficient, steel and air= 99.9% of sound is reflected.

There are 2 problems with this formula.
When water flows in my copper pipes, the metal pipes make noise, we hear it, which means that the sound from the metal is transmitted

into the air.
Maybe the sound simply travels on the surface of solid objects?

I did many tests. and conclusions are.
The string should not be coated in varnish nor in paint, should not be stranded and it should be made of metal. It should be clean and stretched very tight. The string should not

touch
anything even a light touch stops the transverse wave on it. An observation is that when the sound wave travels on (or in?) a very

thick metallic object such as
a big thick industrial nail, a pipe, etc. the sound does not stop when something touches the object. This means that if we want the

string to turn
, let's say a 90 degrees turn, we must connect it to a ticker piece of metal , lets say a thick metallic rod, nailed to a wooden

beam. And even in this case there might be losses.

The resonator box. Of course my first tests were with the tin can and did not work. What worked was this shape.
Only this shape [resonatorboximage] of the resonator box, made of juice box, converts
longitudinal waves in the air to transverse waves in the string , transmits them from air in the solid string.
I think, the walls of this resonator tremble probably because of the property of elasticity. The shape is similar to to the shape of the guitar.
The sound on the other end of the string , mine was 10 meters long, was of bad quality, with an echo.
The shape of the resonator chambers  of the phonographs is horn, and men who own them should try this shape.

Actually the text above barely matters, because this  radiator can  transmit sound into metal!  This is probably because of resonance

property. although it  contradicts to the formula. Those 7.3 cm wide metal  plates vibrate when I clap my hands. The sound travels in the pipes. [radiator]

Either way the article on the wikipedia should be corrected, and the one who wrote it should be banned, fired and disenfranchised.

A few comments about media. Video titled The WORLD's LONGEST TIN CAN PHONE!  they kinda admitted their phone is non functional.

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21 minutes ago, Eiot said:

They say: "When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a diaphragm, converting the

sound waves into longitudinal mechanical vibrations which vary the tension of the string. " . In this quote, they deliberately and criminally omit what the

material the string is made of,

The material doesn’t really matter in terms of how it operates. I remember doing this with string and with copper wire.

21 minutes ago, Eiot said:

nor they point out the shape of the "cans". The waves on the string are not longitudinal.

Yes they are, as they are sound waves.

Quote

anything even a light touch stops the transverse wave on it. An observation is that when the sound wave travels on (or in?) a very

thick metallic object such as
a big thick industrial nail, a pipe, etc. the sound does not stop when something touches the object.

Evidence that they are longitudinal rather than transverse.

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Eiot, geez, calm down!   Even if what people say on wikipedia is wrong (and it often is), it doesn't follow that they were lying!  Maybe they just don't know any better.  And if you are going to tell us it was criminal, you had better tell us what law  they broke!

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18 hours ago, Eiot said:

Actually the text above barely matters

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18 hours ago, Eiot said:

I examined the articles and videos about 'the tin can phone'. I concluded that all the articles and youtube videos about it are fake.

But now let's understand why the tin can phone articles are bullshit. Let's examine wikipedias article en.wikipedia.org/wiki/Tin_can_telephone    Basically they begin their

article saying it works, without providing any technical prove. The whole article is anti-scientific bullshit.

They say: "When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a diaphragm, converting the

sound waves into longitudinal mechanical vibrations which vary the tension of the string. " . In this quote, they deliberately and criminally omit what the

material the string is made of, nor they point out the shape of the "cans". The waves on the string are not longitudinal. They insolently lie that the sound from those cans can travel by a ... textile rope. They lie that it can travel if that textile rope is twisted. Absolutely idiotic. Horrifying! Also, the sound waves reflect off the solid

surfaces!

To confirm this, i read some articles and found the formula.

It is called  Reflection coefficient. (there is also the transmission coefficient formula but I think it is not needed here).

You cannot simply transmit sound from air to metal because of impedance mismatch.
R=reflection coefficient and it is supposed to show how much sound reflects.

[formula image]

where p=density

c=speed of sound

z=impedance

since z=p*c, then
R=(z2-z1)/(z1+z2)
where z is impedance for longitudinal. z=density * speed

Zair=1.29 kg/m3 * 343 m/s = 442

Zsteel(the tin cans are made of steel)=7800 kg/m3 * 5790 m/s=45162000

Zwater=1000 kg/m3 * 1493 m/s=1493000

[airwater]

Reflection coefficient , water and air = 99.9% of sound is reflected.

[steelair]

Reflection coefficient, steel and air= 99.9% of sound is reflected.

There are 2 problems with this formula.
When water flows in my copper pipes, the metal pipes make noise, we hear it, which means that the sound from the metal is transmitted

into the air.
Maybe the sound simply travels on the surface of solid objects?

I did many tests. and conclusions are.
The string should not be coated in varnish nor in paint, should not be stranded and it should be made of metal. It should be clean and stretched very tight. The string should not

touch
anything even a light touch stops the transverse wave on it. An observation is that when the sound wave travels on (or in?) a very

thick metallic object such as
a big thick industrial nail, a pipe, etc. the sound does not stop when something touches the object. This means that if we want the

string to turn
, let's say a 90 degrees turn, we must connect it to a ticker piece of metal , lets say a thick metallic rod, nailed to a wooden

beam. And even in this case there might be losses.

The resonator box. Of course my first tests were with the tin can and did not work. What worked was this shape.
Only this shape [resonatorboximage] of the resonator box, made of juice box, converts
longitudinal waves in the air to transverse waves in the string , transmits them from air in the solid string.
I think, the walls of this resonator tremble probably because of the property of elasticity. The shape is similar to to the shape of the guitar.
The sound on the other end of the string , mine was 10 meters long, was of bad quality, with an echo.
The shape of the resonator chambers  of the phonographs is horn, and men who own them should try this shape.

Actually the text above barely matters, because this  radiator can  transmit sound into metal!  This is probably because of resonance

property. although it  contradicts to the formula. Those 7.3 cm wide metal  plates vibrate when I clap my hands. The sound travels in the pipes. [radiator]

Either way the article on the wikipedia should be corrected, and the one who wrote it should be banned, fired and disenfranchised.

A few comments about media. Video titled The WORLD's LONGEST TIN CAN PHONE!  they kinda admitted their phone is non functional.

I did this as child, using yoghourt pots and string. It worked very well. With tin cans I imagine it depends on how free the base is to move, so a thinner one will be better. But there is no doubt that it works in principle, so long as you keep the string taut.

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23 hours ago, Eiot said:

The waves on the string are not longitudinal. They insolently lie that the sound from those cans can travel by a ... textile rope. They lie that it can travel if that textile rope is twisted. Absolutely idiotic

Instead of being so contemptuous of the thoughts of others, perhaps you might like to discuss the Physics of how this might or might not happen.

That is consider mechanisms of transmission.

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This seems to be a case of looking for complication, in something absolutely simple.

Imagine two people facing each other holding a rope taut. When one pulls harder, the other is pulled forward. When one relaxes, the other moves in the opposite direction due to the tension he's applying. So a rope under tension transmits a duplicate back and forward motion from one end to the other.

There's the mechanism of transmission.

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-You cannot set a rod (or a string) into vibration by striking it in the cross sectional area.
As a matter of fact waves on a string are transverse.

-soft,  porous materials, fibre ropes are acoustic insulators.

About the resonator box.

In the tuning fork resonance videos, the walls of the resonator boxes are suspiciously thick. Lets hear what the narrators say: "When the one box is placed such that its opening is a few centimetres from the others opening striking one tuning fork sets up a sympathetic vibration in the other" or
"the vibrations of the first tuning fork travel through the air and pushed on the second tuning fork"
It seems they underestimate the properties of the resonating boxes.   As a matter of fact ,
the sound beam enters in the second resonator box and sets its walls to vibrate, and the walls set the tuning fork to vibrate.

by the way Such the resonator box must surely improve the carbon rod microphone  cuz if you look at yt videos they all show their carbon rod microphones without proper wooden resonators.

I don't know why the radiators plates resonate so easily, has it to do with the nodes,nodal lines and thickness? It is up for you to investigate.

In my last test I made this toy of wooden box and it works but it's far from good...there are losses cuz i could not sand the steel can receiver, and the string did not touch wooden surface tightly enough.

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15 hours ago, Eiot said:

-You cannot set a rod (or a string) into vibration by striking it in the cross sectional area.

Why does a bell ring when you strike it?

Here's a simple physics lab where the speed of sound was measured in precisely the fashion you say doesn't work

Quote

As a matter of fact waves on a string are transverse.

Repeating this doesn't make it true. You can get both transverse and longitudinal waves in a string

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16 hours ago, Eiot said:

-You cannot set a rod (or a string) into vibration by striking it in the cross sectional area.
As a matter of fact waves on a string are transverse.

-soft,  porous materials, fibre ropes are acoustic insulators.

About the resonator box.

In the tuning fork resonance videos, the walls of the resonator boxes are suspiciously thick. Lets hear what the narrators say: "When the one box is placed such that its opening is a few centimetres from the others opening striking one tuning fork sets up a sympathetic vibration in the other" or
"the vibrations of the first tuning fork travel through the air and pushed on the second tuning fork"
It seems they underestimate the properties of the resonating boxes.   As a matter of fact ,
the sound beam enters in the second resonator box and sets its walls to vibrate, and the walls set the tuning fork to vibrate.

by the way Such the resonator box must surely improve the carbon rod microphone  cuz if you look at yt videos they all show their carbon rod microphones without proper wooden resonators.

I don't know why the radiators plates resonate so easily, has it to do with the nodes,nodal lines and thickness? It is up for you to investigate.

In my last test I made this toy of wooden box and it works but it's far from good...there are losses cuz i could not sand the steel can receiver, and the string did not touch wooden surface tightly enough.

Waves on a string can be also longitudinal, so long as the string is held taut by something elastic at either end, which it is in the setup we are talking about.

Why not get 2 empty yoghourt pots, make a hole in the centre of the base of each, pass a string through with a knot at each end to stop it going through the hole and pull the whole thing tight between you and someone else?

You will find that, with a string 10m or so long, the person at the far end can speak in a low voice into their pot and, if you hold your pot to your ear, you will hear them quite clearly - through the string. You can prove it by then letting the string go slack and trying again.  I did this as a child.

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