Detection sensitivity of frequency modulated (FM) and constant frequency (CF) signals in temporal masking conditions in the Mongolian gerbils

Abstract

The auditory systems would be sensitive to temporal changes in frequency of sounds. We hypothesized that frequency modulation would play an important role in perception. And in this study, the difference in detection sensitivity between frequency-modulated signals (FM) and constant frequency signals (CF) in temporal masking conditions was examined in three Mongolian gerbils (Meriones unguiculatus) by GO-NOGO procedure. We focused on their detection sensitivity of three types of signals; upward FM, downward FM, and CF. The frequency range of each FM was from 4 to 7 kHz, and CF was 6 kHz. We set S+ that signals were presented between white noise bursts (BW: 0 to 17.5 kHz), and then signals were temporally masked by white noise. In contrast, we set S− in which silence was presented instead of signals. Subjects were trained to detect whether signals were presented or not. After subjects reached criterion (80%), each stimulus was presented randomly and attenuated in amplitude. We investigated their response rate to each S+. Result showed that their detection sensitivity to FM was higher than that of CF. It suggests that FM is superior to CF in recognition for subjects. [Research was supported with financial assistance from MEXT.]