Music functions as an extensive emotional and cognitive tool that varies in meaning across the lifespan. Drawing on decades of music‑psychology research, this study examines how five genres—classical, pop, jazz, grunge rock, and ambient (designer) music—serve distinct psychological functions for adolescents, young adults, middle‑aged adults, and older listeners. Classical music is linked to cognitive enhancement, calm, and nostalgia; pop music facilitates mood regulation, identity formation, and social bonding; jazz offers intellectual engagement and emotional complexity that deepens with age; grunge rock provides cathartic expression and identity reinforcement during adolescence and early adulthood, later shifting to nostalgic remembrance; ambient music supplies low‑arousal support for focus, relaxation, and therapeutic applications, especially in later life. The paper integrates traditional survey and experimental findings with large‑scale streaming‑data analytics, demonstrating that genre‑specific listening patterns can be quantified through skip rates, replay frequency, and personalized recommendation algorithms. Results highlight the age‑dependent psychological roles of each genre and illustrate how data‑driven methods can validate and extend theoretical models of music‑induced emotion regulation, identity development, and cognitive support across the human lifespan.