Experiments by Schurmann et al. show that tactile senses can activate the human auditory cortex. Currently vibrotactile stimuli can be used to facilitate hearing in normal and hearing-impaired people. To test for the auditory areas activated by touch, Schurmann et al. tested subjects while stimulating their fingers and palms with vibration bursts and their fingertips with tactile pressure. They found that tactile stimulation of the fingers lead to activation of the auditory belt area, which suggests that there is a relationship between audition and tactition. Therefore, future research can be done to investigate the likelihood of a tactile–auditory sensory substitution system. One promising invention is the 'Sense organs synthesizer' which aims at delivering a normal hearing range of nine octaves via 216 electrodes to sequential touch nerve zones, next to the spine.