Wave aspect of light (diffraction) Explain why you can hear from behind a wall but you cannot see around it although both light and sound have a wave nature !
 A: You can, just not very much - larger wave lengths diffract more, and sound waves have much much larger wavelengths than visible light (with $\lambda < 1\mu m$).
But radio waves, which are just like visible light with much larger $\lambda$ diffract all the time, you can receive radio signals even when you're not a straight line from the transmitter.
I suggest you read more about Arago's/Poisson's spot to see an example of diffraction in visible light. You should also read about Young's experiment too.
Good luck!
A: I'll give you an example you can see something behind a wall but not hear something. Put a mirror over the wall and you will see what is behind the wall due to light reflection. And futhermore if you are in a house the window will protect you from noise but let through the light from the mirror.
So as you can see the setup of the experiment determines the result.
Sound needs a medium to propagate. During propagation takes place the dissipation of the sound wave. To proof that dissipation is a natural phenomenon take a tube and let sound through it. Behind the tube you will hear the sound around the tube. But a deep frequency you'll hear all around and a high frequency sound is more directed straight. For sound the dissipation is more important (dominant) than reflection.
For light it is different. In gases there is a dissipation due to reflections on gas molecules and dust. The image from this dissipation is nearly perfect diffuse. Only if there are hot slices of air (in desert) one get a mirage.
Not taking in account gases light is going only in straight lines (more exact along geodesic paths). To get bend the light has to touch (to be under the influence) of an edge or to switch from air to an other medium (to switch between different media). But the dispersion angle for light is due to observation very low.
The statement

although both light and sound have a wave nature

leads to a simplification which doesn't takes in account the need in medium for sound and the propagation of light without any medium. Smashing this two phenomena in one, it is said that then smaller the wavelength than lower the dispersion. But this simplification in my eyes is misleading (but it holds since lights frequencies are much higher sound frequencies).
