I Why does a drip of water into water make a noise?

[cmb]

What is the 'gloop' noise; what actually makes the energy noise (from gravitational/kinetic into ... what transformation?), how is that transformed energy then coupled into a propagating wave in air?

Further, whatever 'that' is, is it the same for an ocean wave, just godzilions of little drops all making the same noise close together in time and space, and if one could separate them out then the ocean would be one drip noise after another. Or something else?

 

[davenn]

What is the 'gloop' noise; what actually makes the energy noise

A Q back at you ... why is a sound made when a hammer hits something ?

The reason is the same

 

[Delta2]

In terms of high school physics the collision of two bodies, creates vibration of the molecules on the two colliding surfaces and these vibrations pass into the surrounding air and form the sound waves.

In terms of graduate physics, Navier -Stokes equations which the air obeys as a fluid medium, have as solutions pressure waves in the medium when the medium (air in this case) is disturbed by the motion/vibration of other bodies.

 

[cmb]

The hammer and anvil will vibrate because the materials they are made of are elastic and there is a bulk oscillation of volume once struck, leading to oscillations normal to the surface.

I understand that water is incompressible and that any waves that would carry away energy exchange to be surface waves, not bulk volume oscillations.

I could agree that some waves might be possible, but surely there would be quite a low frequency cutoff due to the viscosity of the water and its inability to couple the energy effectively to air, the amplitudes would be negligible for the spectrum of the 'plop' in the multi kHz range.