Establishing a comprehensive framework for investigating the profound connection between music and spiritual experiences, this chapter first introduces the Metaphysics of Quality by Robert Pirsig. This philosophical approach offers specific ontological positions on spirituality and empiricism, laying the groundwork for the exploration of music and trance phenomena, often considered outside of empirical studies. Drawing upon the Metaphysics of Quality, the study then adopts a multidisciplinary approach to unravel the intricate dynamics of musical trance. It addresses the prevailing dichotomy in existing literature, which often isolates either the socio-cultural significance or the psychoacoustic mechanisms of music in trance states. In order to bridge this gap, the inquiry simultaneously delves into music's role as a culture-specific sign and a sonic inducer within spiritual contexts. Through cognitive and psychological lenses, the study explores theories of altered states of consciousness (ASC), examines ethnographic examples of musical trance practices from nine distinct geographical regions, and provides comparative analysis of field recordings to gain insights into the psychoacoustic properties accompanying trance states. While direct causality between sound and trance induction remains elusive, the study identifies common sonic patterns hinting at a complementary function of music in ASC. Various units of statistical regularities in music emerge as significant elements linking sound to perceptual and socio-cultural contexts of trance rituals. Through integration within a non-dualist eco-social model of sonic signification, the chapter provides a nuanced understanding of music's multifaceted role in facilitating spiritual experiences across diverse cultural landscapes.