An acoustic wave generated at ground level and propagating vertically through the lower ionosphere produces partial reflections of radio waves transmitted by a vertical sounder. The Doppler effect of the radio wave, produced by the acoustic wave motion, depends on the properties of the ionosphere and of the atmosphere. We show that this permits the determination of both the neutral-temperature and the electron-density profiles of the lower E region. The accuracy and the advantages of this method are discussed, and some experimental results are compared with those of other measurement techniques.