Formants are peaks in the speech (harmonic sound) spectrum, labeled by number, from lowest frequency to highest. These concentrations of energy occur at different frequencies, depending on the length of the vocal tract. Listeners use the relationships between formant peaks to perceive speech sounds. The first three (lowest) formants are important because one can distinguish almost all speech sounds on the basis of energy in the region of these three. Touch: mechanical displacements and other physical impacts on the skin. Proprioception: perception mediated by kinesthethic and vestibular receptors. Somatosensation: a collective term for sensory signals from the body. Hand-pen demo: close eyes, hold pen and asked what is felt, instead of saying, the pen, the person describes what the pen is. Subtracting (less interesting) sensation of the pen; focus directed on what the pen feels". Cutaneous rabbit demo: 2 separate locations stimulated multiple times in quick succession feels like a rabbit, hopping across the skin between the 2 locations.