As far as i know this is called ESP (Electronic Shock Protection) that was firstly introduced by SONY. it works by reading the CD faster than the standard 1X (150kB/sec) required for normal CD playback and storing the data in a memory buffer.

This was done so that if the optical pickup is jolted out of alignment by an external shock, the CD player would read from the memory buffer until the pickup came back on track and resumed reading.