Proximal binaural sound can induce subjective frisson Running head title : Sound frisson induced by proximal binaural sound

Sound frisson is a subjective experience wherein people tend to perceive the feeling of chills in addition to a physiological response, such as goosebumps. Multiple examples of frisson-inducing sounds have been reported in the large online community, but the mechanism of sound frisson is still elusive. Typical frisson-inducing sounds contain a looming effect, in which a sound seems to be approaching close to one’s peripersonal space. Previous studies on sound in peripersonal space have reported objective measurements of sound-inducing effects, but few studies have investigated the subjective experience of frisson-inducing sound. Here, we investigate whether sound stimulus moving around the human head can also produce subjective ratings of frisson. Our results show that the participants experienced sound-induced frisson when auditory stimuli were rotated around the head, regardless of the sound sources. This manuscript is under review in somewhere (4/12/2019). Introduction Looming sounds (sounds that move closer or approach) enhance human arousal1. Changes in behavioral, physiological, or neurophysiological states caused by looming sounds are collectively referred to as the looming effect. A previous study has shown that an approaching sound can produce a stronger looming effect than a receding sound2. Moreover, the human voice or a pure tone stimulus elicits a stronger looming effect than white noise2. Humans also experience the looming effect when sounds approach them in threedimensional (3D) space. Bach et al. reported a spatial looming effect wherein participants exhibited skin conductance responses1, indicating that spatial sound can evoke changes in one’s phasic alertness and physiological state. Looming sound may sometimes produce frisson. For example, the approaching buzz of a mosquito g, besides being annoying, can induce frisson, i.e., chills. Frisson and chills have also been discussed in the context of music experiences3, where the terms are described as an “effect that shows close links to surprise” and are associated with a “pleasant tingling feeling,” raised body hairs, and goosebumps4,5. Recent neuroimaging studies have reported neural correlates of frisson or chills while listening to music6,7. However, how the musical pleasure and chills can be modified by the looming effect is unknown. What if music were to approach listeners in 3D space? An interesting question would then be whether “looming music” or “binaural music” increases the sensation of chills and pleasure. This manuscript is under review in somewhere (4/12/2019). Certain types of auditory stimuli that are proximal to the listener’s body are known to produce frisson. For example, Barratt and Davis (2015) studied the autonomous sensory meridian response (ASMR) associated with sensory tingling or frisson8. The ASMR is possibly induced by sounds, such as whispering, crisp sounds (metallic foil, tapping fingernails, etc.), and the sounds produced by slow movements2. However, data regarding the psychoacoustic feature that causes the ASMR or frisson are limited. Although a recent study has elucidated and synthesized the sensory aspect of noise sounds by using auditory statistics9, reproducing ASMR-inducing sounds with computational methodology remains difficult. Considering that ASMR-inducing sounds are usually recorded with a binaural microphone, the difference between diotic and dichotic listening may be an important factor in inducing frisson. However, whether a proximal binaural sound increases the subjective rating of frisson has not been systematically tested. Here, we investigated whether a sound stimulus moving around the human head can produce a subjective rating of frisson. Specifically, we examined whether a moving sound stimulus can produce more subjective frisson than static sound stimuli. In addition, we addressed the question of whether the intensity of frisson is moving-velocity dependent. For this purpose, we changed the speed of the sound source in a parametric manner and instructed the participants to evaluate the created sound stimuli. We also addressed the question of whether individual differences in impulsive behaviors may affect the rating of frisson. This manuscript is under review in somewhere (4/12/2019).