During the Cold War years, listening to “Western” music–especially those genres of “ill-repute” such as jazz and rock ‘n roll–could get a person sent to the Gulag.
So people got creative and made bootleg records of this music on old x-rays, called “bones” or “ribs.” Because the quality was so poor, people called the experience of hearing them to be “listening through sound”–meaning sound with some faint music coming through. Watch a less-than-15-minute documentary on “X-Ray Audio” here:
Image source: X-Ray Audio
Check out the great X-Ray Audio Project website here.