Question

what does it mean when the video says there is an acoustic mirror effect?

sound in the water stays in the water and sound above the water says above the water.

sound produces in the water gets magnified like light in a curved mirror.

an observer can see sound but only on the surface of the water (like in a mirror)

sound produced outside of the water is magnified into the water.

Explanation:

The acoustic mirror effect in water - related sound contexts typically refers to how sound at the water - air interface behaves. The first option, "Sound in the water stays in the water and sound above the water stays above the water", aligns with the concept of the acoustic mirror effect where the water - air boundary acts as a sort of 'mirror' for sound, keeping sound within their respective media (water or air above water). The second option's idea of sound in water being magnified like light in a curved mirror is incorrect as the acoustic mirror effect isn't about magnification of underwater sound in that way. The third option is wrong because sound can't be seen. The fourth option is incorrect as the acoustic mirror effect doesn't involve magnifying sound from outside into the water.

Answer:

A. Sound in the water stays in the water and sound above the water stays above the water.