It is important for acousticians to know the directivity of the sound radiated from openings and single panels exited by sound incident on their other side. Davy has published a series of papers on the theory of the directivity of the sound radiated from openings and single leaf panels. For a single leaf panel, significantly above the coincidence frequency for a fixed angle of radiation or significantly above the coincidence angle for a fixed frequency, the previous version of Davy's theory underestimates the measured sound pressure level. This under-estimation has now been addressed by using the wave impedance of an infinite version of the panel with the restriction that the magnitude of the imaginary part of the wave impedance is less than or equal to that of an infinite limp version of the panel. Since the publication of Davy's papers on directivity, the authors have been able to access more experimental measurements with which to compare Davy's theory. This paper gives the results of comparisons between Davy's theory and these experimental values of directivity by giving the mean and standard deviation of the differences between the experimental and theoretical relative sound pressure levels at an angle to the normal of the opening or single leaf panel of sound radiation or sound incidence. For single leaf panels, the value of the damping loss factor which was used in the theory to minimize the root mean square sum of the mean and standard deviation of the differences between theory and experiment is also given. These values of damping loss factor are much larger than normal for the materials of which the panels are constructed. The need for these large damping loss factors and the restriction on the wave impedance is believed to be due to the finite size of the panel.
