Neurocinematics is an emerging interdisciplinary field at the intersection between Human-Computer Interaction, Brain-Computer Interfaces (BCI), and cinematics, that explores the use of brain and physiological data (such as functional Near Infrared Spectroscopy (fNIRS)), to evaluate a variety of media content. While many studies focused on comparing features of physiological activity between genres, this study aims to examine the cinematic content in the same genre but in different modes. Specifically, we are interested in the brain responses to audio and visual content, which have a similar emotional impact, in horror movies. Using non-invasive brain monitoring devices (fNIRS) targeting participants' prefrontal cortex, we collected and analysed their brain activity responses in comparison to subjective experience while watching a series of horror video clips. The results show changes in cognitive and emotional responses during the A, audio only modes, V, visual only modes, and M, audio and visual together modes for the horror stimulus, across fNIRS and subjective data. Our results are in line previous findings and bring novel insights into how brain activity can help researchers evaluate audio-visual content and promise an exciting future for adaptive horror experiences.