स्पष्ट प्रतिध्वनि (echo) सुनने के लिए, परावर्तक सतह श्रोता से कम से कम कितनी दूरी पर होनी चाहिए? (ध्वनि की चाल ≈ 340 m/s मानें)

What is the minimum distance a person must stand at from a reflecting surface to hear a distinct echo (assuming speed of sound in air is approximately 344 m/s)?

Sound in the human audible frequency range is commonly referred to as:

Assertion (A): Sound produced from a larger tabla is louder than sound produced from a smaller tabla when struck with equal force. Reason 1 (R1): Loudness increases with an increase in the surface area of the vibrating body. Reason 2 (R2): A larger tabla produces sound of a higher pitch.