The phenomenon which is responsible for this effect is called diffraction.
Diffraction is the ability of a wave to propagate when it meets an obstacle or a slit. When the wave encounters the obstacle or the slit, it 'bends' around it and it continues propagate beyond it. A classical example of this phenomenon is when a sound wave propagates through a wall where there is a small aperture (as in the example of this problem)
Answer:
diffraction
Explanation:
It is due to the diffraction.
Diffraction is the phenomenon in which the waves (light or sound) bends their path after striking to the sharp edged object or the sharp orifice.
Diffraction is possible if the wavelength of the waves has the order of width of the orifice.
