Earlier investigations of pupil size variation during auditory stimulation involved delivery of simple auditory tones. In this study, we investigated pupil size variation in response to auditory stimuli which involved verbal stories. In our study, twenty four participants listened to scenarios with headphones while sitting in front of an eye tracker and rated stories on two bipolar dimensions: emotional valence and arousal. We analyzed pupil data after finishing subjective ratings of scenario. The results showed that the pupil size is significantly large during the story which carried strongly negative sentiment compared to the story with neutral content. To sum up, our results showed that systematically designed scenarios with highly arousing negative sentiment significantly affected the subjects' physiological pupil reaction as well as their subjective experiences. In the future, it might be possible to use pupil size variation as a predictor for sentimental content of scenarios. Auditory emotion-related cues might also be utilized to modulate the users' emotional reactions in affective computing.