Why is soap foam so good at blocking sound although it is mostly just air?

Question

I have noticed this while bathing when soap foam went into my ears and it almost completely blocked the outside sound. This seems weird as soap foam is just all air with some liquid

In: 18

Answer 1

Sound transmits poorly through varying materials, especially when air gaps are introduced.

For soundproof walls, air gaps effectively “decouple” the main wall assembly components from each other, reducing the ability of low-frequency sounds to easily transmit through the full assembly.