SOUND PROPAGATION IN A LAYER OF A FRESH-WATER RESERVOIR UNDER WINTERTIME CONDITIONS.

Measurements of sound pressure decay with distance were carried out in the flat part of a reservoir at a distance of 200-250 m from a very gently sloping shore, where the depth of the water layer was about 0. 6 m. The thickness of the ice cover did not exceed 0. 4 or 0. 5 m. The ice was covered with a layer of snow, which was saturated from below with water. A wide-band ring-shaped sound radiator was placed at the middle depth of the water layer. Holes 15 cm in diameter were drilled through the ice for recording of the vertical sections of the sound pressure distribution. The water level in the drill hole was taken as the zero depth level of the receiver.