Behavioral thresholds for a 15-ms probe tone were obtained for three parakeets in a backward, forward, and a combined forward and backward masking paradigm as a function of masker frequency. For all three paradigms, threshold improved dramatically (~10 dB) when masker frequency was ^±20 Hz of the probe frequency compared to the equal masker and probe frequency condition. In the region of the "tip" of the masking function the Q₁₀ dB values were 140, 20, and 70 for the backward, forward, and combined backward and forward masking paradigms, respectively. The sharpness of tuning in the frequency region of the probe is considerably greater than that found for humans tested with the same stimuli. Probe threshold also varied as a function of masker level and masker duration for both forward and backward masking paradigms. Temporal summation data for short tones and noises are consistent with previous data obtained with longer signals. [Work supported by NIMH.]