Detection cues in forward masking and their relationship to off-frequency listening.

Conventional and restricted-listening psychophysical tuning curve paradigms were used to evaluate the masking ability of forward maskers of different envelope characteristics, and the relationship between off-frequency listening effects and the envelope characteristics of both the variable masker and stationary masker used to restrict listening to a narrow region surrounding the probe. Maskers were selected so as to differ widely in the degree of fluctuation in their envelopes. The masker with the largest amplitude fluctuations exhibited greater forward-masking ability than other stimuli; this effect was observed on the high-frequency branch and within the tip region of the tuning curve. It is suggested that differences in masking ability may reflect the use of different signal detection cues. The results are also consistent with previous reports [D. Johnson-Davies and R.D. Patterson, J. Acoust. Soc. Am. 65, 756-770 (1979); B.J. O'Loughlin and B.C.J. Moore, J. Acoust. Soc. Am. 69, 1119-1125 (1981a)] which suggest that off-frequency listening is a factor contributing to the sharpness of psychophysical tuning curves. This effect is largely dependent, however, on the envelope characteristics of both variable and stationary maskers.