For hearing the loudest ticking sound by the ear:
$(a)$ Find the angles $x$ and $y$ in the figure below.
$(b)$ Name the phenomenon observed here.
$(c)$ State the laws of the phenomenon.

(N/A) The angle between the tube and the reflecting surface is $50^{\circ}$. The normal is perpendicular to the surface,so the angle of reflection $r$ is $90^{\circ} - 50^{\circ} = 40^{\circ}$. According to the laws of reflection,the angle of incidence $i$ is equal to the angle of reflection $r$. Therefore,$\angle x = \angle r = 40^{\circ}$ and $\angle y = \angle i = 40^{\circ}$.
$(b)$ The phenomenon observed is the reflection of sound.
$(c)$ The laws of reflection of sound are:
$(i)$ The incident sound wave,the reflected sound wave,and the normal at the point of incidence all lie in the same plane.
$(ii)$ The angle of incidence is always equal to the angle of reflection $(\angle i = \angle r)$.