1. The problem statement, all variables and given/known data What do echo and reverbation have in common? 2. Relevant equations We can hear sounds with a difference of 0.1 seconds. Speed of sound 340 m/S. the distance the sound travels is 34 m. the distance from the wall is 17m. 3. The attempt at a solution They are the reflection of sound waves, they are formed when sound waves meet a hard surface, they cause a repetition of the sound. The waves keep having the same frequency (the source doesn't change); They have the same speed and length as they had before the reflection, because the environment doesn't change. Is there anything else?