Effects of peripheral nonlinearity on psychometric functions for forward-masked tones.
Psychometric functions (PFs) for forward-masked tones were obtained for conditions in which signal level was varied to estimate threshold at several masker levels (variable-signal condition), and in which masker level was varied to estimate threshold at several signal levels (variable-masker condition). The changes in PF slope across combinations of masker frequency, masker level, and signal delay were explored in three experiments. In experiment 1, a 2-kHz, 10-ms tone was masked by a 50, 70 or 90 dB SPL, 20-ms on-frequency forward masker, with signal delays of 2, 20, or 40 ms, in a variable-signal condition. PF slopes decreased in conditions where signal threshold was high. In experiments 2 and 3, the signal was a 4-kHz, 10-ms tone, and the masker was either a 4- or 2.4-kHz, 200-ms tone. In experiment 2, on-frequency maskers were presented at 30 to 90 dB SPL in 10-dB steps and off-frequency maskers were presented at 60 to 90 dB SPL in 10-dB steps, with signal delays of 0, 10, or 30 ms, in a variable-signal condition. PF slopes decreased as signal level increased, and this trend was similar for on- and off-frequency maskers. In experiment 3, variable-masker conditions with on- and off-frequency maskers and 0-ms signal delay were presented. In general, the results were consistent with the hypothesis that peripheral nonlinearity is reflected in the PF slopes. The data also indicate that masker level plays a role independent of signal level, an effect that could be accounted for by assuming greater internal noise at higher stimulus levels.
Schairer
Kim S
KS
Center for Hearing Research, Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA. schairerk@boystown.org
Nizami
Lance
L
Reimer
Jason F
JF
Jesteadt
Walt
W
D000328:Adult; D001288:Attention / Q000502:physiology; D001309:Auditory Threshold; D001489:Basilar Membrane / Q000502:physiology; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D017711:Nonlinear Dynamics; D010470:Perceptual Masking / Q000502:physiology; D010897:Pitch Discrimination / Q000502:physiology; D011571:Psychoacoustics