Which of the following statements is/are correct about sound? (A) Sound is produced by vibrating objects. (B) Sound does not require a medium to travel. (C) In humans, the vibration of the vocal cords produces sound. (D) Plantation on the roadside can reduce noise pollution.

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.