Credits to Wouter Gordts
Both individuals with normal or impaired hearing (problems of the outer and/or middle ear) can perceive sound
Internal sounds are re-internalized in an audible way without the air medium. Inner soundscapes have been recorded through contact microphones, which function as sound transducers. The transmission of the sound is realized through direct contact of the "stethophone" to the head - bone conduction - thus creating a full closed circuit, starting from the contact recording of the inner sounds to the contact transmission of them.
During this chain process, the sound is being kept internal and is being reproduced again internally, directly to the inner ear, deviating the air transmission of sound waves which is the hearing through the external ears.