When a photographic emulsion of the boiled type is treated with 800 kc ultrasonic energy at an energy level of 5 w/sq cm during the after‐ripening or digestion period, an increase the photographic sensitivity of that emulsion occurs. No significant change in the gamma or the grain size distribution of the emulsion results from this treatment. The mechanism appears to be a transport phenomenon which disrupts grain‐sensitizing‐agent concentration gradients in the intergrain gelatin matrix.