Relative contributions of on- and off-frequency spectral cues in increment detection

Abstract

Increment detection is often used as a measure of intensity resolution, where a listener detects a brief increment in intensity in a longer duration stimulus. Recent findings suggest that listeners rely on multiple cues rather than on-frequency energy cues. The relative contributions of on- and off-frequency cues are evaluated in five normal-hearing young adults. Detection thresholds for a 50-ms increment added in the middle of a 450-ms, 1000-Hz pedestal were obtained in quiet, telegraph noise (TN), and notched-noise (NN) conditions. The pedestal level was 60 dB SPL. NN stimuli were generated by filtering TN while keeping the notch geometrically centered at 1000 Hz. The NN-notches were also varied by increasing the notch-width unevenly on either side of the center frequency. The low-frequency cutoffs of the NN-notches were 125, 250, 500, and 750 Hz while the high-frequency cutoffs were 1500, 2000, and 4000 Hz. Although the NN-notches were centered at 1000 Hz, increment detection thresholds were poorer in NN conditions than in quiet. Detection thresholds were similar in TN and NN with the narrowest notch conditions. Results suggest that listeners may rely on a decision process based on multichannel on- and off-frequency cues. [Supported by BU research and scholarship grant]