The sound field in front of a wall
This chapter considers the sound field in front of a wall, which is assumed to be perfectly plane, smooth and infinitely large. However, the results will also be valid approximations for walls encountered in practice as long as their dimensions are much larger than the wavelength and any irregularities in the surface are much smaller than the wavelength of the sound. First, the case of normal incidence is considered, i.e. the wall is perpendicular to the direction of propagation of the incoming sound wave, which is assumed to be a single harmonic sound with angular frequency. The chapter derives expressions for the behaviour of the sound field in front of a totally reflecting wall. Only a qualitative description and presentation of the main results is given and only in the case of diffuse sound field incidence.