This study investigates whether the relationship between word-level stress detection and musical aptitude differs across first-language (L1) backgrounds.While prior work has shown that musical aptitude predicts prosodic sensitivity, it remains unclear whether this relationship is modulated by linguistic experience.Sixty intermediate-to-advanced learners of Spanish (20 German, 20 French, 20 Korean) completed an odd-one-out stress discrimination task and the Mini-PROMS musical aptitude test assessing Melody, Accent, Tempo, and Tuning.Spanish word-familiarity ratings served as a proficiency control.Results showed that German learners outperformed Korean and French participants, consistent with cross-linguistic differences in the use of lexical stress.Among the musical subtests, only Melody significantly related to stress discrimination across all L1s, suggesting a shared sensitivity to pitch variation.The Accent score interacted with L1, showing a positive trend for German and French learners but not for Korean participants.No effects emerged for Tuning or Tempo.These findings indicate that pitch-related perceptual skills, rather than rhythmic or timbral ones, relate to stress sensitivity in L2 Spanish, highlighting the role of specific musical dimensions in prosodic learning.