A Singing Tube is a phenomenon
in which sound
is produced by placing a bunsen
flame inside a tube.
The varying pressure waves inside the tube set up compressions
that rapidly oscillate
. This occurs because the pressure variances travel vertically up the tube and then reflect due to the end effect
of the tube and re-enter the tube now travelling downwards. The up-wave and down-wave combine to form a pattern. If the pressure waves
are of the right frequency
they assume the pattern of a standing wave
. This "stationary
" wave generates a frequency
much higher than a normal pressure wave.
Prediction of the frequency emitted is difficult because many standing waves are formed (fundamental
s, and subsequent harmonics
The composition of the tube has no effect on the sound because it is the collumn of air - not the tube - that is vibrating. The effect can also be achieved by heating high resistance gauze
using direct current
or by a heated wire mesh placed internally.