Auditory feedback is both air- and bone-conducted. This means that we hear ourselves speaking not only by the sound that arrives at our ears, but also by way of the bones in the skull, which emphasises low frequencies. This is why we do not sound to ourselves the way we sound to others.
Proprioceptive feedback is the sense of movement and position, or the direct feedback from muscles. This type of feedback can be illustrated by the ability to touch the tip of your nose with your eyes closed.
Tactile feedback is the information one receives from one's sense of touch. The articulators, for instance, come into contact with one another. Auditory and tactile feedback are external feedback systems, because the information they provide is delivered to external receptors.