Water was passed slowly through a 6mm inner diameter tube hanging 1750mm from the surface of the water. The water depth was 150mm in a standard bucket of height 200mm, diameter 260mm.
Taken from a single recording, with only intermediate silences removed. They are quiet, so turn up your volume.
The sounds are remarkably similar. Note the strong background noise from the recording computer. The dominant frequencies of this noise are roughly:
|Relative Magnitude||Frequency (Hz)|
- Droplet impact consistently forms large surface bubbles and the standard "bloop" noise
- The surface cavity seems to form the large surface bubble, which survives for an instant and then pops. Size is approx. 40-50mm in diameter.
- The collapse of the main cavity sometimes forms small (<10mm) bubbles which can survive for a long time.
- Phsyically disrupting cavity/bubble formation eliminates the droplet noise
- Rising pitch seems to correspond in time with the closing of the bubble cavity. (need photos...)
- Weak "spitting" noise as bubbles break
- Adjusting height so main cavity does not form almost totally eliminates the droplet noise.
SpectrogramAll the spectrograms look the same, modulo some noise.
- Note the contaminating noise frequencies at the bottom.
- The strong vertical bars correspond to small "tss" noises which I believe are bubble breaks and very small splashes.
- The rising frequency feature in the middle of the sound (0.4s-0.5s)is the characteristic "bloop" noise associated with water droplets. It is very distinct and occurs in all the recordings.