Sean Ealy Behavioral and Social Science Abstract: Which has a bigger impact on the emotions that we experience when we listen to a sound: the feelings and memories that we associate with the sound based on our past experiences, or the musical qualities of the chord that is formed by the tones that we are hearing? The answer to this classic “nature vs. nurture” question could be important in marketing, medicine, music, or any area where it might be useful to use sound to manipulate people's emotions. In this experiment I asked 20 subjects to record their emotions as they listened to 8 different sounds that are embedded in the experiment’s website. The resulting data reinforced to some extent the idea that the inherent properties of major chords cause positive emotions while minor chords cause negative emotions, but the correlation was not as strong as expected. The police siren, the only sound with no chord qualities, produced the strongest reaction of all, suggesting that the association of specific sounds with life events may have an even larger effect on emotion than chord quality. Certain chords are known to reliably produce a predictable emotional response, and my hypothesis was that this chordal quality would play the largest role in determining emotions. My hypothesis was not supported, however, since listener familiarity and pre-determined opinions about the sounds seemed to have a greater effect on emotions than the chordal quality of the sound.