Copy X Authored teaching scenario. The features below are constructed to show how a shared property is reasoned about. Nothing here was measured from a real tape, a real deck or a real recording. Features present: F1 throughout Broadband noise floor raised by about 9 dB F2 00:12.400 Dropout, 40 ms, left channel only F5 00:04.900 Door closing, 300 ms F6 throughout High-frequency rolloff above 12 kHz