  We study the principal aspects of the interaction between acoustic phonons
and two-dimensional electrons in quantizing magnetic fields corresponding to
even denominator fractions. Using the composite fermion approach we derive the
vertex of the electron-phonon coupling mediated by the Chern-Simons gauge
field. We estimate acoustic phonon contribution to electronic mobility,
phonon-drag thermopower, and hot electron energy loss rate, which all,
depending on the temperature regime, are either proportional to lower powers of
T than their zero field counterparts, or enhanced by the same numerical factor
as the coefficient of surface acoustic wave attenuation.
