Playground phone
A playground phone is a simple acoustic intercom for playgrounds.
construction
A playground telephone typically consists of at least two vertically installed stainless steel tubes with stainless steel funnels welded on top, which are embedded in concrete in the ground so that the funnels are at a height accessible to children. They are connected underground with a hose. If a participant speaks into one of the funnels, the sound is transmitted through the pipe and hose to the other funnel (s).
principle
The sound transmission based on indifferent reflections within the tube (s) and also occurs within tube systems on. Similarly structured speaking tubes were common in seafaring to enable communication on ships, for example between the captain and helmsman or machinist. The limited cross-section of the tube is acoustically a bandpass that transmits the speech frequencies , but only transmits high and low-frequency interfering noises at all or at all.
Similar devices
Individual evidence
- ↑ Playground telephone. In: www.borchers-kommunalbedarf.de. Retrieved October 5, 2016 .
- ^ Playground telephone - E. Beckmann. In: www.beckmann-cashagen.de. Retrieved October 5, 2016 .
- ↑ Playground telephone. In: Kommunalbedarf Groeger. Retrieved October 5, 2016 .
- ↑ Special hose for tubular telephone. In: Kommunalbedarf Groeger. Retrieved October 5, 2016 .