The exciton lifetime has been found to be repeatedly tuned by a MHz frequency acoustic driving without degradation of the optical properties of CdS crystals. The increase in the lifetime, up to 5&percent;, followed by its ∼20&percent; decrease has been detected with increasing driving amplitude. The lifetime increase can now be understood as due to reduction in the electron-hole wave function overlap in electric fields generated by the driving. The decrease in the recombination lifetime is ascribed to a widening of the potential well trapping the exciton due to variations in the local-crystal environment at acoustic driving. ©1998 American Institute of Physics.