In a "straight tube" standing wavelengths are 1/4, 3/4, 5/4, ... of a wave
because the wave
in the tube has a crest on one (antinode) and a through (node) on the other
end.
In a "conical tube" standing wavelengths are 1/2, 2/2, 3/2, ... of a wave
because there's a
crest (antinode) on both ends.
Terry B