ABSTRACT
@#In this study, the asymmetry of the main effects of action, background and tonal frequency during a pitch memory processingwere investigated by means of brain activation. Eighteen participants (mean age 27.6 years) were presented with low andhigh frequency tones in quiet and in noise. They listen, discriminate and recognize the target tone against the final tonein a series of four distracting tones. The main effects were studied using the analysis of variance (ANOVA) with action (towring (rubber bulb) vs. not to wring), background (in quiet vs. in noise) and frequency (low vs. high) as the factors (andlevels respectively). The main effect of action is in the right pre-central gyrus (PCG), in conformation with its contralateralbehavior. The main effect of background indicated the bilateral primary auditory cortices (PAC) and is right lateralized,attributable to white noise. The main effect of frequency is also observed in PAC but bilaterally equal and attributable tolow frequency tones. Despite the argument that the temporo-spectral lateralization dichotomy is not especially rigid asrevealed by the main effect of frequency, right lateralization of PAC for the respective main effect of background clearlydemonstrates its functional asymmetry suggesting different perceptual functionality of the right and left PAC.