What causes an echo in a room?

Related questions

1. How does echo cancellation work?
2. How do Alexa skills make money?
3. How do I make my room quieter?
4. Do you need reverb and delay?
5. Why do we hear more clearly in a furnished room than in an empty room?
6. Why we Cannot hear echo in a small room?
7. Does Delay go before reverb?
8. What causes echo on phone line?
9. Why excessive reverberation is undesirable?
10. Why is rt60 important?

Tags

1. #effect
2. #acoustic
3. #ceilings
4. #walls
5. #drastically
6. #waves
7. #sound
8. #tiles
9. #reduce
10. #replacing
11. #objects
12. #absorb
13. #concrete
14. #hanging
15. #carpet
16. #floor
17. #cause
18. #echoes
19. #hardwood
20. #ceiling