The aerated-water spectrum has a resonance at 1200 Hz. This probably corresponds to a quarter-wave open pipe resonance with a wavelength of 0.3 m. Hz is likely a higher-order mode, possibly including transverse excitation. After the bubbles have dissipated, the lowest resonance is at about 3300 Hz, almost three times higher than in aerated water. Hz are candidates.
New features appear that probably correspond to the flexure resonances of the cup itself.
Most lines are heavily damped, with the exception of the doublet at about 2500 Hz and the line at 4400 Hz. This supports the interpretation of the spectral lines as in Fig. 3.2 as being due to resonances of the water column. Acknowledgements The author is grateful to W.L. Shackleford and J.W. Dooley for their comments and insights. W.L. Shackleford, personal communication.