This study aims to provide psychophysical data on English language listeners’ ability to discriminate tone pitch contours. Just noticeable differences (JND) of F0 contour changes were measured in six native listeners of American English. Previous work in our lab found English listener thresholds for offsets of falling tones to be significantly lower than those for onsets of rising tones. To what extent this difference is due to the position of the F0 shift versus the direction of the F0 contour is unclear. In this study, we control for four experimental factors: stimulus type (speech, nonspeech), position of F0 shift (onset, offset), direction of shift (upward, downward), and F0 contour direction (falling, rising). Preliminary results reveal that English listeners had significantly lower psychophysical thresholds for F0 shifts at the offset than at the onset. No significant difference was found for F0 shift direction, F0 contour direction, or stimulus type. The current data suggest that the F0 shift position was the primary determinant in our previous study and replicate other findings showing that English listeners perceive tones on a psychophysical base. Future work will examine these results in relation to those of native tone language listeners.