  We report experimental measurements of the acoustic emission associated with
the bursting of a gas bubble at the free surface of a non-newtonian fluid. On
account of the viscoelastic properties of the fluid, the bubble is generally
elongated. The associated frequency and duration of the acoustic signal are
discussed with regard to the shape of the bubble and successfully accounted for
by a simple linear model. The acoustic energy exhibits a high sensitivity to
the dynamics of the thin film bursting, which demonstrates that, in practice,
it is barely possible to deduce from the acoustic measurements the total amount
of energy released by the event. Our experimental findings provide clues for
the understanding of the signals from either volcanoes or foams, where one
observes respectively, the bursting of giant bubbles at the free surface of
lava and bubble bursting avalanches.
