We show that in generic isotropic holographic theories the longitudinal Langevin diffusion coefficient along the string motion is larger compared to that of the transverse direction. We argue that this is in general a universal relation and we derive the generic conditions in order to be satisfied. A way to violate the relation is to consider anisotropic gauge/gravity dualities. We give an explicit example of this violation where the noise along the transverse direction is larger than the noise occurring along the quark motion. Moreover, we derive the effective world-sheet temperature for any generic theory and then the conditions for negative excess noise. We argue that isotropic theories can not have negative excess noise and we additionally remark that these conditions are difficult to get satisfied, indicating positivity of the excess noise even in a large class of anisotropic holographic theories, implying a strong universal property.

We investigate the behaviour of the lowest nonhydrodynamic modes in a class of holographic models which exhibit an equation of state closely mimicking the one determined from lattice QCD. We compute the lowest quasinormal mode frequencies for a range of scalar self-interaction potentials and find that the damping of the quasinormal modes at the phase transition/crossover falls off by a factor of around two from conformality after factoring out standard conformal temperature dependence. The damping encoded in the imaginary part of the frequencies turns out to be correlated with the speed of sound and is basically independent of the UV details of the model. We also find that the dynamics of the nonhydrodynamic degrees of freedom remains ultralocal, even to a higher degree, as we deviate from conformality. These results indicate that the role of nonhydrodynamic degrees of freedom in the vicinity of the crossover transition may be enhanced. *