The practice of listening to subtle, inner sounds during meditation to concentrate and elevate the mind has a long history in various religions around the world, including Islam, Christianity, Hinduism, Buddhism, Jainism, and Sikhism. Today there are a number of new religious movements that have made listening to the inner sound current a cornerstone of their teachings. These groups include the Radhasoamis, the Divine Light Mission, Eckankar, the Movement of Spiritual Inner Awareness (MSIA), MasterPath, the Sawan-Kirpal Mission, Quan Yin/Ching Hai, Manavta Mandir, ISHA, and a number of others. In this study we provide a historical and comprehensive overview of these movements and how they have incorporated listening to the inner sound as part of their spiritual discipline. We are particularly interested in the distinctive and nuanced ways that each group teaches how to listen to the inner sound current and how they interpret it in their own unique theologies.

1. Introduction; 2. The Neurobiological Basis of Shabd Yoga; 3. The History of Nad and Shabd Yoga; 4. The Sufi Emphasis on the Sound Current; 5. The Sant and Sikh Practice of Shabd and Nam; 6. The Radhasoami Tradition; 7. The Sound Current Tradition in the West; 8. Paul Twitchell and Eckankar; 9. The Sound Current Tradition in Other Religions; 10. Conclusion.