A tin can phone is a type of acoustic (non-electrical) speech-transmitting device made up of two

tin can A steel can, tin can, tin (especially in British English, Australian English, Canadian English and South African English), or can is a container made of thin metal, for distribution or storage of goods. Some cans are opened by removing the to ...

paper cup A paper cup is a disposable cup made out of paper and often lined or coated paper, coated with plastic-coated paper, plastic or wax paper, wax to prevent liquid from leaking out or soaking through the paper. Disposable cups in shared environment ...

s or similarly shaped items attached to either end of a taut string or wire. It is a particular case of mechanical

telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunications services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is ...

, where

sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

(i.e., vibrations in the air) is converted into

vibration Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the os ...

s along a liquid or solid medium. These vibrations are transmitted through the medium (string) and then converted back to sound.

History

Before the invention of the electromagnetic telephone, there were mechanical acoustic devices for transmitting spoken words and music over a greater distance, faster than the speed of sound in air. The very earliest mechanical telephones were based on transmission through

pipes Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circu ...

or other

physical media Physical media refers to the physical materials that are used to store or transmit information in data communications. These physical media are generally physical objects made of materials such as copper or glass. They can be touched and felt, ...

, and among the very earliest experiments were those conducted by the British physicist and

polymath A polymath or polyhistor is an individual whose knowledge spans many different subjects, known to draw on complex bodies of knowledge to solve specific problems. Polymaths often prefer a specific context in which to explain their knowledge, ...

Robert Hooke Robert Hooke (; 18 July 16353 March 1703) was an English polymath who was active as a physicist ("natural philosopher"), astronomer, geologist, meteorologist, and architect. He is credited as one of the first scientists to investigate living ...

from 1664 to 1685.McVeigh, Daniel P
An Early History of the Telephone: 1664–1866: Robert Hooke's Acoustic Experiments and Acoustic Inventions
,

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

website. Retrieved January 15, 2013. This work in turn cites: * Richard Waller and edited by R.T. Gunther. "The Postthumous Works of Robert Hooke, M.D., S.R.S. 1705. Reprinted in R.T. Gunther's "Early Science In Oxford", Vol. 6, p. 185, 25Grigonis, Richard
A Telephone in 1665?
TMCNet Technews website, December 29, 2008. From 1664 to 1665 Hooke experimented with sound transmission through a taut extended wire. An acoustic string phone is attributed to him as early as 1667.Giles, Arthur (editor)
County Directory of Scotland (for 1901-1904): Twelfth Issue: Telephone (Scottish Post Office Directories)
Edinburgh: R. Grant & Son, 1902, p. 28. Consolidated Telephone Co

For a short period, acoustic telephones were marketed commercially as niche competitors to the electrical telephone, as they did not fall within the scope of its patent protection. When

Alexander Graham Bell Alexander Graham Bell (; born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born Canadian Americans, Canadian-American inventor, scientist, and engineer who is credited with patenting the first practical telephone. He als ...

's telephone patent expired and dozens of new phone companies flooded the marketplace, acoustic telephone manufacturers could not compete and quickly went out of business. Their maximum range was very limited, but technical innovations (resulting in about 300 patents) increased their range to approximately , or more under ideal conditions.Jacobs, Bill
Acoustic Telephones
, TelefoonMuseum.com website. Retrieved January 15, 2013. This article in turn cites: * Kolger, Jon. "Mechanical or String Telephones", ATCA Newsletter, June 1986; and * "Lancaster, Pennsylvania Agricultural Almanac for the Year 1879: How to Construct a Farmer's Telephone", John Bater's Sons.; and * "Telephone Experiences of Harry J. Curl as told by him to E. T. Mahood, During the summer of 1933 at Kansas City, Missouri: First Telephone Experience." An example of one such company was Lemuel Mellett's 'Pulsion Telephone Supply Company' of Massachusetts, which designed its version in 1888 and deployed it on railroad rights-of-way, purportedly with a range of ."The Pulsion Telephone"
New Zealand: ''Hawke's Bay Herald'', Vol. XXV, Iss. 8583, January 30, 1890, p. 3. In the centuries before tin cans and paper cups became commonplace, other cups were used and the devices were sometimes called "lovers' telephones". During the 20th century, they came into common use in preschools and elementary schools to teach children about sound vibration.

Operation

String with an anchored twist to change direction

When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a

diaphragm Diaphragm may refer to: Anatomy * Thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Pelvic diaphragm or pelvic floor, a pelvic structure * Urogenital diaphragm or triangular ligament, a pelvic structure Other * Diap ...

, converting the

sound wave In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...

s into longitudinal

mechanical vibration Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the oscill ...

s which vary the tension of the string. These variations in tension set up longitudinal waves in the string which travel to the second can, causing its bottom to vibrate in a similar manner as the first can, thus recreating the sound, which is heard by the second person. The signal can be directed around corners with at least two methods: The first is to create a loop in the string which is then twisted and anchored to another object. The second uses an extra can positioned on the apex of the corner; the string is threaded through the base of the can to avoid coming into contact with the object around which the signal is to be directed.NPASS2 String Telephones
, “Corner Busters” photos taken 7 October 2012.

References

External links

{{Commons category, Tin can telephones
Tin Can Telephone

How to Make a Tin Can Telephone
Traditional toys Telephony equipment

History

Operation

See also

References

External links