The "voice in your head" is physically sub-vocalized by your throat muscles. This audio prevents you from hearing yourself think.
Articulatory Suppression: The audio engine mixes Brown Noise (low rumble) with band-passed Pink Noise. This covers the human vocal range (300Hz-3400Hz). Wernicke's Area cannot process internal dialogue when the external auditory input is fully saturated in the same frequency band.
Random noise actually helps signal detection in small doses, but in high doses, it acts as a firewall.
Signal-to-Noise Ratio: We effectively lower the SNR of your own thoughts to zero. By introducing high-amplitude noise, neural synchronization (required for complex thought formation) is disrupted.