# Do soap bubbles reflect sound?

• spareine

#### spareine

Bats in my garden do not seem to notice soap bubbles. Do soap bubbles reflect sound?

Probably only very weakly since soap bubbles are elastic and will absorb a lot of sound rather than reflecting it.
Any sound which does reflect is probably beneath the bat's hearing sensitivity

On the other hand, according to classical physics the reflection coefficient is R = (Z1-Z2)2 / (Z1+Z2)2, where Z=ρc is acoustic impedance and Zair<<Zwater. That implies R≈1 due to the huge impedance mismatch.

But since the soapy water film is much thinner than it is wide, one has to take into account the kinematics of the film and air resistance on the film as it vibrates. For similar reasons a thick wood panel will reflect much more sound than a sheet of facial tissue will.

I remember an article about a recording studio (I forget where).
The idea was that studio setup would as best as possible capture instruments and vocals with minimal complication from sound reflection.
The solution was covering most of walls and ceiling with plastic foam bubbles.

## 1. Why do we see soap bubbles forming when we blow through a bubble wand?

When we blow through a bubble wand, we are creating a thin layer of soap film that traps air inside. The surface tension of the soap film allows it to hold onto the air, forming a spherical shape and creating a bubble.

## 2. Can sound waves pass through soap bubbles?

Yes, sound waves can pass through soap bubbles. However, the bubbles are not very good at reflecting or transmitting sound. This is because the soap film is very thin, and the air inside is constantly moving and changing shape, making it difficult for sound waves to travel through.

## 3. Why do soap bubbles make a popping sound when they burst?

When a soap bubble bursts, the thin soap film breaks apart into smaller droplets and the air inside escapes. This release of air creates a popping sound as the bubbles collapse.

## 4. Do soap bubbles reflect sound differently than other objects?

Yes, soap bubbles reflect sound differently than other objects. This is because the soap film is very thin and flexible, making it difficult for sound waves to bounce off of it. Other solid objects, like walls or furniture, are better at reflecting sound waves because they are more rigid and have a smoother surface.

## 5. Can soap bubbles be used to amplify or dampen sound?

Soap bubbles are not very effective at amplifying or dampening sound. This is because they are not very good at reflecting sound waves. It is possible to create a small echo or resonance inside a soap bubble, but it is not strong enough to significantly amplify or dampen sound.