Characterizing the attenuation and/or saturation effect of the acoustic scanner noise in auditory event-related functional magnetic resonance imaging

The analysis of event-related functional magnetic resonance imaging when presenting auditory stimuli and/or investigating auditory cortex and related areas is hindered by inherent acoustic scanner noise (ASN), which can alter the properties of the acquired time-series data. Therefore, it is necessary to account for ASN in the analysis, and one step towards this goal is to characterize the attenuation and/or saturation effect of the hemodynamic response due to ASN. Towards this end, this study examined how the effect of ASN is dependent on repetition time (TR) and the inter-stimulus interval (ISI), two experimental parameters that affect the acoustic signal-to-noise ratio of the experimental paradigm. Results indicate that a decrease in TR (e.g., 6 s to 1.5 s) results in an increase in saturation and an attenuation of the estimated hemodynamic response peak with respect to the baseline signal level. There was no statistical difference in peak response between the two ISI values used, 12 s and 18 s.