Question

Explain why you can hear two people talking even when they walk around a corner.

Answer 1

Hint: The ability of waves to bend around corners or obstacles is known as diffraction. The diffraction phenomenon effectively takes place when the obstacles have a size similar or comparable to the wavelength of the waves.

Complete Step-by-Step solution:
Generally, it is agreed upon that without obstruction waves travel outward in a straight line from the source to their destination. Of course it can travel in three dimensions but each “line” of the wave will propagate in a straight line. However, there is a phenomenon called diffraction which is exhibited by all waves.
Diffraction is bending of light around an obstacle or corners. When waves are travelling they encounter an obstacle, they tend to bend around the obstacle and continue propagating. For example, if you place your hand in a pool and use your other hand to generate a wave, on encountering your hands, the water waves bends around your hands and you still see waves at the back of your hands.
This is the exact same way sound travels around a corner to be heard by someone who is not even in the direct “line of sight” of the listener. As the sound waves propagate three dimensionally away from the speaker’s mouth, the sound waves colliding with the walls just “wraps” itself around the wall and continues in that direction.
Hence, we can hear people talking around the corner mostly due to diffraction of sound waves

Note:
Nonetheless, there other ways the sound can get to a listener around the corner. One way is reflection of those sound waves from the ground or other walls around. Whenever this happens, it allows the listener to misjudge the direction of the source of the wave. Ever heard a sound and you thought it was from a certain direction and you ended up realizing it’s from another direction? That’s a reflected sound.