WAEC Physics 2011 Paper

Concept:Echo and reverberation are both caused by reflection of sound, but they differ by the time interval between the original and reflected sound.Explanation:An echo is heard as a distinct, separate sound when the reflected sound returns after a noticeable delay.This delay is usually greater than $0.1\,\text{s}$, so the ear can distinguish the original sound from the reflected sound.Reverberation occurs when many reflected sounds reach the ear almost immediately.The time interval here is very short, so the reflections overlap and produce a continuous, prolonged sound.Therefore, the main difference is that the time interval between the incident sound and the reflected sound is shorter for reverberation.Answer:Option B — the time interval between incident sound and reflected sound is shorter for reverberation.