String Telephone Experiments

(supervisor: Tony Cook)

Nature of project: experimental, experimental

Available to full-time physicists or joint students.

Project description and methodology

One of the things we mention in the Chaos and Communication module are the precursor point to point communications available before the invention of the telephone. This project looks at the communication capabilities of string telephones i.e. 2 (empty) baked bean cans with a piece of stretched string between them. In a piece of retro science I would like the project students to investigate the hypothetical question of how string telephones could have been used in the era before Alexander Graham Bell's Patented Invention.

This may sound like retro-science, but it has real applications in nature e.g. the Spiders Web with signals transmitted by a caught insect to the spider -how close does the spider have to be to its prey? How are vibrations transmitted through the radial parts of the web to allow the spider to triangulate?

A successful project will develop beyond the above in one/some of the following directions:
1) How is sound attenuated down different types of string, and what is the maximum distance that information can be transmitted?

2) Do standing waves contribute to attenation factors - what about tension?

3) Produce a frequency response for different types of string.

4) Investigate splitting the signal with a third piece of stirng (eaves dropping) - how does the signal strength vary with angle - demonstrate an effective way of using a string telephone around corners.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: 1) Investigate the noise contribution of outside factors such as the wind

2) Can you demonstrate the string telephone principle using strands from a spider's web?

3) Build a large scale artifical web and investigate (with microphones at different positions) how a spider might be able to triangulate vibrations onto a particular X, Y coordinate?

Initial literature for students:

  1. The Postthumous Works of Robert Hooke, M.D., S.R.S. 1705. Reprinted in R.T. Gunther's: The Life and Workof Robert Hooke, Early Science in Oxford. vol 6. (Oxford) Oxford University Press (1930), 9-10.
  2. http://strowger-net.telefoniemuseum.nl/tel_tech_mechanical.html (accessed 2015 Sep)
  3. Blackstock, David T. (2000). Fundamentals of Physical Acoustics, p.141, Wiley–IEEE, ISBN 0-471-31979-1
  4. Talbot-Smith, Michael (2013). Audio Engineer's Reference Book. CRC Press. p. 2.52. ISBN 1136119744

Novelty, degree of difficulty and amount of assistance required

Relatively easy to get started, but a lot of calibration type work needed.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Decide upon the materials you will need and experimental setupChristmas
Investigate effects of string length on audio attenuationend of February
Investigate eaves droppingmid-March
Finish remaining experimental tasksEaster

Students taking this project will have to submit a full risk assessment form