“…The ABG closure was calculated using the four-tone average for pre- and post-operative air conduction and bone conduction thresholds in 86.3 per cent of the papers; 4 , 6 , 7 , 14 – 21 , 23 – 53 , 55 , 59 , 62 however, 3 kHz was only used in 45.1 per cent of these calculations 6 , 7 , 15 , 16 , 20 , 21 , 24 , 28 , 32 – 34 , 38 , 40 – 44 , 47 , 51 , 53 , 55 , 57 , 59 . The remaining papers either substituted 3 kHz with 4 kHz (in 79.2 of papers), or averaged 2 kHz and 4 kHz (in 16.7 per cent).…”