Let me have a two-can string telephone

24 03 2011

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Did you play with string telephones as a child? This is a game that deaf children most likely don’t play…. unless they can lip read the length of a string.

I got my chance last week …. it was thrilling! A client was giving a presentation and his topic was an invention : antennae. He used cans and plastic cups as an analogy to show how antennae works. His prop was a pair of tin cans with string between them, and a pair of smaller plastic cups with string between them.

He made a sound into a tin can, the sound went into the can, travelled along the string as a transference wave and came out of the other tin as a sound wave again.  How the antennae works is pretty much the same.  An electrical signal goes into the antenna, the antennae converts to a radio signal and on the receiving end converts it back to an electrical signal, and that would be music or image. This is the basic principles of how antennae works.  It is a form of transducer that converts one form of energy into another.

The really exciting bit was that when he spoke into the can, I could understand every word he said.

Eyeballs straight ahead! – I had my head at 90 degrees! – I swear!

I was amazed. Unexpectedly, the two pairs sounded different too. Why is this?  A micro strip antennae allows you to reconfigure frequency. This antennae allows you to reconfigure the personal frequency which means, say, a radio wave would work at 15 gigahertz but a mobile would be 20 gigahertz, they work in different frequencies.  The antennae, the configuration has changed.  In this case, it became smaller so the plastic cup works at a higher frequency than the longer tin can, which means the plastic cup would be better for female voices compared to the longer tin can which is better for male voices.  So this antennae allows you to reconfigure its personal frequency by employing a very small patch of capacity. This highlights why voices can be harder to understand on the telephone.

Antennae is a really important invention, you’ll find one in every telephone, mobile phone, computer, wireless computer, wi-fi. It was really cool to have an expert explain to me in layman’s terms how antennae work, and to allow me to have the opportunity to listen for myself. This is real hands-on hearing!

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One response

24 03 2011
Catherine Mellor

I can see that if I really work at understanding the geek talk here, and smiling nicely, I just might increase my understanding of how sound travels. Thanks for sharing, Tina! Catherine

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