Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture.For diffraction, λ∼ width of gap.Sound waves from a television are diffracted through doorways. Light waves from a television are not diffracted through doorways because wavelength of light ≪ width of doorway or wavelength of sound . But the wavelength of sound is similar to width of doorway.