The sound heard by a person after the reflection of the sound generated by him is called

Step 1: Analyze the question The question asks for the name of the sound a person hears after the sound they produced has reflected off a surface (like a wall, cliff, or building).

Step 2: Explain the concepts

• Reverberation: The persistence of sound in an enclosed space because of multiple reflections. The reflected sounds merge with the original sound, and there is no distinct separate repetition. A large empty hall is a typical example.
• Resonance: This happens when an object vibrates at its natural frequency because it is driven by another source of the same frequency. An example is an air column in a tube resonating with a tuning fork.
• Echo: A distinct, separate repetition of the original sound, heard after reflection from a distant surface. For an echo to be heard clearly, the reflecting surface must be at least about 17 m away. The human ear can distinguish two sounds only if they are at least 0.1 s apart, and sound travels about 340 m/s, so the round trip must be at least 34 m, which means a distance of at least 17 m.
• Audibility: This refers to whether a sound can be heard, meaning it is within the range of human hearing (about 20 Hz to 20,000 Hz) and loud enough.

Step 3: Apply to the question The sound is produced by the person, reflected by a surface, and then heard again by the same person. This is the definition of an echo.

Step 4: Check the other options

• Reverberation involves overlapping reflections with no distinct repetition, so it does not fit.
• Resonance is about matching vibration frequencies, not reflection.
• Audibility is just about whether the sound can be heard.

Answer: C. echo

Exam tip: Remember "Echo = Elsewhere reflected, Evident repeat." If you hear a distinct repeat of your own sound, it is an echo. If it just sounds prolonged or "boomy" in a hall, it is reverberation. This is the same principle used in sonar and in depth-finding of the sea using echo sounding.