A descriptive model of under- and over-shoot patterns in the temporal masking function of a narrow-band noise

Abstract

Complex temporal patterns of under- and over-shoot (i.e., enhanced and diminished detection) at onset and offset of a 200-ms, 400-Hz-wide noise masker (2500 Hz center frequency) have been reported for a temporal masking paradigm [Formby et al.., J. Acoust. Soc. Am. 102, 3161(A) (1997)]. The paradigm measured detection of a 5-ms sinusoidal signal (1900 or 2100 Hz) at 43 temporal positions preceding, during, and following the masker. Efforts to model under- and over-shoot patterns in the temporal masking functions will be considered. The modeling strategy is similar to that used in the study of vestibular adaptation [Formby et al., 21st Meeting of Association for Research in Otolaryngology, 1988], and allows for quantification of the relative amplitudes, time constants, and delays of excitatory and adaptive processes. Linear combinations of exponential functions are used to represent the effects of excitatory masking and adaptation. Suppression and adaptation of suppression may also play roles in the masking process. These effects can be evaluated in our scheme by including corresponding exponential functions to represent the processes. The least-squares fitting model will be described and parameter estimates for the model will be presented for a range of masker levels. [Work supported by ONR.]