Hare Krishna. In this material world we are conditioned by the false ego which consists of the body, mind and intelligence. The mind can present certain scenario's to us and we then use our intelligence to either accept or reject those ideas. The intelligence give us the ability to discriminate from the desirable and the undesirable. Real intelligence is described as the ability to distinguish between spirit and matter. Thus our power of discrimination may also be affected due to material conditioning. These different inner workings are what constitute our inner voice. And beyond these layers of false ego is the Supersoul located beside our own Atma within the heart.
Bhagavad-Gita 6.7: For one who has conquered the mind, the Supersoul is already reached, for he has attained tranquility. To such a man happiness and distress, heat and cold, honor and dishonor are all the same.