A semiclassical derivation is given of Handel’s expression [Phys. Rev. Lett.34, 1492 (1975); Phys. Rev. A22, 745 (1980); Phys. Rev. A26, 586 (1982)] for the Hooge [Phys. Lett. A29, 139 (1969); Physica83B, 19 (1976)] parameter &agr;H. This may explain why Handel’s expression for &agr;Halways agrees with the experimental data, despite the fact that there seem to be serious objections to Handel’s derivation of his results.