Results from scientific studies of brain function have suffered from failure to replicate in subsequent studies. We hypothesize that, in order to obtain consistent results, it is necessary to standardize at least the posture and attention level in physiological studies of human brain activity associated with auditory perception. Here we focus on the effects of a minor postural changes on near-infrared spectroscopy (NIRS) measures of brain activity. In particular we recorded NIRS signals during “parallel” and “crossed” arm/hand positions. Six of 22 channels (4 on the left and 2 on the right hemisphere) showed significant level changes associated with hand crossing (p<0.001). Thus, even such simple postural changes may affect the reliability and reproducibility of the results of physiological study of brain function. We recommend that experimenters in physiological studies of speech perception require participants to keep their hands on a surface and feet on the floor.