Question

When we speak, is it retained forever? Or it just propagates for few meter and finished permanently?

Answer 1

If you're referring to the sound waves we produce when we speak, they dissipate.

This is caused by several factors:
1. The waves spread out like the waves created when you drop a pebble in a calm lake. The wave is spreading out, reducing the "energy density."
2. The waves' energy is absorbed by other matter. This translates primarily into heat.
3. Molecular interaction between the air molecules. There is energy lost on molecular collisions.

There are probably others.

Answer 2

Thanks for your reply.
Is it retained permanently in atmosphere? Is there any zone or layers where sound is saved? Can today's science discover the discussion between two persons , say before 50 years?

Answer 3

Entropy is entirely too random for us to reconstruct ancient sources of minute energy.

Answer 4

Entropy would the transition of organized energy (in the form of a pressure wave created by speaking) to atomic vibrations (in the form of heat).

Answer 5

would be created by the transition*