Unruh model for the Einstein-Rosen charge: Squealing Wormholes?
  We present two kinds of acoustic models for the massless electric charge conceived by Einstein and Rosen in the form of a bridge (wormhole throat). It is found that the first kind of modelling requires a thin layer of exotic matter at the bridge. We also derive an acoustic equation that exclusively characterizes the model. Using a second kind of model, it is demonstrated that the Einstein-Rosen charge has a sonic Hawking-Unruh temperature proportional to +-1/$beta$, where $beta$ is the size of the charge. This suggests that (squealing!) wormholes can also be formally accommodated into Unruh's fluid model. 
K.K. Nandi and D.H. Xu