May 19, 2022 11:27 PM
https://www.sciencenews.org/article/pipe...ration-air
EXCERPTS: In 1860, physicist Hermann von Helmholtz [...] devised an equation relating the wavelength of a pipe’s fundamental tone (the lowest frequency at which it resonates) to pipe length. Generally, the longer a pipe is, the lower its fundamental tone will be.
But the equation doesn’t work in practice. A pipe’s fundamental tone always sounds lower than the pipe’s length suggests it should according to Helmholtz’s formula. Fixing this problem requires adding an “end correction” to the equation [...] 0.6 times the radius of the pipe. Why this was, nobody could figure out.
A break in the case came in 2010 [... by studying...] how air moves through playing organ pipes using cigarette smoke. When an organ pipe sounds, a vortex indeed forms over the pipe’s rim, the team reported March 14...
[...] What’s more, this vortex is capped by a hemisphere of resonating air. This vibrating air cap ... effectively lengthens the organ pipe by the exact amount that must be tacked on to Helmholtz’s formula to explain the pipe’s fundamental tone... (MORE - missing details)
EXCERPTS: In 1860, physicist Hermann von Helmholtz [...] devised an equation relating the wavelength of a pipe’s fundamental tone (the lowest frequency at which it resonates) to pipe length. Generally, the longer a pipe is, the lower its fundamental tone will be.
But the equation doesn’t work in practice. A pipe’s fundamental tone always sounds lower than the pipe’s length suggests it should according to Helmholtz’s formula. Fixing this problem requires adding an “end correction” to the equation [...] 0.6 times the radius of the pipe. Why this was, nobody could figure out.
A break in the case came in 2010 [... by studying...] how air moves through playing organ pipes using cigarette smoke. When an organ pipe sounds, a vortex indeed forms over the pipe’s rim, the team reported March 14...
[...] What’s more, this vortex is capped by a hemisphere of resonating air. This vibrating air cap ... effectively lengthens the organ pipe by the exact amount that must be tacked on to Helmholtz’s formula to explain the pipe’s fundamental tone... (MORE - missing details)