Comment on "Brillouin scattering measurements on optical glasses"

It is shown that a frequency variation of the attenuation $\gamma \sim {\omega }^2$, which agrees with current relaxation theories, is not too far outside the uncertainties of the available Brillouin-scattering experiments. Ultrasonic measurements, on the other hand, indicate a similar frequency dependence, when compared to the Brillouin-scattering values.