A conical air column will produce the same fundamental frequency as an open cylinder of the same length and will also produce all harmonics.
Conical air columns are employed in several of the woodwind musical instruments: oboe, bassoon, saxophone, and others.
How does one tuning fork produce resonance at three different lengths?
the speed of sound is v= m/s v = ft/s = mi/hr.
The closed tube fundamental resonance
will be produced at length L = cm = ft , which is 1/4 of a wavelength.