Study on effects of presence of cue-tone on psychophysical tuning curves

Abstract

Our previous study indicated that tunings of the auditory filter were sharpened by the presence of a cue-tone [Kidani, Miyauchi, & Unoki (2012), ISH2012]. It is unclear, however, whether the modification of the auditory filter due to the cue-tone is caused by excitation or suppression, because tip of the filter is normalized at 0 dB. Psychophysical tuning curves (PTCs) can show that the detection threshold is decreased at the probe frequency or increased around the probe by the presence of cue-tone, indicating excitation and suppression respectively. PTCs, because, are measured as masked threshold of probe by narrow-band noise. This study aims to consider the effect of the presence of cue-tone by measuring of PTCs. In present study, PTCs were measured in simultaneous masking in the absence and presence of cue-tone for four probe frequencies. The probes were presented at 10 dB above each absolute threshold. The frequency and level of the cue-tone were same as the probe. The result revealed that filter-Q, as regarded as the sharpness of tuning, was increased by the presence of cue-tone when the probe frequencies were 1.0 and 2.0 kHz, while the filter-Q was not changed when the probe frequencies were 0.5 and 4.0 kHz.