Sound therapy operates on the principle of "Brainwave Entrainment," a process where the brain’s naturally occurring electrical frequencies align with the periodic rhythm of an external auditory stimulus. This phenomenon is facilitated by the "Frequency Following Response" (FFR), a neural mechanism where the auditory cortex synchronizes its firing rate to the frequency of an incoming sound.

Therapeutic applications often utilize Binaural Beats—a process where two slightly different frequencies are played into each ear. The brain perceives a third "phantom" frequency, which is the mathematical difference between the two. For instance, if 300Hz is played in one ear and 310Hz in the other, the brain entrains to a 10Hz Alpha frequency, associated with relaxation. For a technical analysis of the hardware requirements for delivering high-fidelity entrainment, the Sound Therapy Market overview provides a breakdown of specialized headphones and frequency generators. By targeting specific brainwave states (Alpha, Theta, or Delta), clinicians can non-invasively modulate a patient's cognitive state to alleviate symptoms of anxiety and insomnia.