  A large linewidth of electronic transition of an electron trapped in a bubble
("bubblonium") possesses natural, or radiative, and inhomogeneous components.
The latter mechanism of the line broadening requires dissipation. Dissipation
of optical-frequency quantum into a liquid helium leads to an emission of an
acoustic wave. The possibilities of detection of this acoustic signal are
discussed in this paper. Finally, the low temperature analogues with several
hard-to-observe astrophysical phenomena are discussed.
