Sensory substitution is a change of the characteristics of one sensory modality into stimuli of another sensory modality.
A sensory substitution system consists of three parts: a sensor, a coupling system, and a stimulator. The sensor records stimuli and gives them to a coupling system which interprets these signals and transmits them to a stimulator. In case the sensor obtains signals of a kind not originally available to the bearer it is a case of sensory augmentation. Sensory substitution concerns human perception and the plasticity of the human brain; and therefore, allows us to study these aspects of neuroscience more through neuroimaging.
Sensory substitution systems may help people by restoring their ability to perceive certain defective sensory modality by using sensory information from a functioning sensory modality.