© 2015 IEEE.Functional near infrared spectroscopy (fNIRS) is a noninvasive optical imaging technique which unables the measurements of the oxy-hemoglobin and deoxy-hemoglobin (metabolic) changes associated with cognitive activity. The proposed system uses fNIRS to detect neural activities arising from an auditory oddball task at preforontal cortex. In this paper data analysis of the fNIRS measurements acquired from the forehead during cognitive tasks is presented. The aim of this study was to invastigate the differences in the hemodynamic response of right and left hemisfer in 10 healthy young. Subjects pressed a button in response to the target stimulus. The fNIRS were recorded using the 'oddball' paradigm in which two stimuli (target and standard) were presented in random order by headphones. Standard deviation, mean value, max value, peak to peak (p-p), area of the under the curve are calculated for each channel. One way ANOVA analysis is applied and according to the results max value (p=0,024), standard deviation (p=0,028), sum (p=0,016) and mean value (p=0,018) are significantly different in two hemisfers. Data analysis results revealed that the blood oxygenation is higher in right frontal lobe than the left.