Table 1.

Estimates of gain change from two methods (fourth and fifth columns). The gain with a 0.8-kHz Pre was estimated from I∕O functions fitted to each subject’s GOM data using Eqs. 1, 2, 3, 4. For S1, S4, and S5, I∕O functions also were fitted to GOM data measured with an on-frequency precursor. The difference between these two estimates of gain is shown as gain change. The two-point gain change estimates were obtained by subtracting signal thresholds for on- and off-frequency precursor conditions with a single fixed masker level. The fixed masker level used is indicated in parentheses. A 95% confidence interval (CI) was constructed for the two-point gain change estimates. The sixth and seventh columns compare the additivity-of-forward-masking (AFM) threshold predictions (when data were available) and measured on-frequency precursor thresholds.

Subject	Gain, 0.8-kHz Pre	Gain, 4.0-kHz Pre	Gain change	Two-point gain change	Two-point 95% CI	Additivity pred	Measured value
S1	45.37	29.50	15.86	16.17 (70 dB)	14.60, 17.74	38.47	43.93
S2	41.75	–	–	9.10 (80 dB)	4.95, 13.23	–	47.00
S3	55.60	–	–	20.28 (75 dB)	16.29, 24.60	–	41.79
S4	45.66	37.05	8.60	8.56 (75 dB)	7.81, 9.31	38.15	41.38
S5	43.33	32.54	10.79	12.03 (65 dB)	10.34, 13.72	35.28	39.03
S6	44.89	–	–	9.62 (75 dB)	7.96, 11.28	34.74	39.86