X curve


Stands for ‘extended’, as opposed to the ‘N’ (normal) curve, which is the same as the Academy Curve.

The ‘X’ curve is also known as the ‘wide-range curve’, and is codified in ISO Bulletin 2969. Specifications call for pink noise — at listening position in a re-recording situation or two-thirds of the way back in a theatre — to be flat to 2 kHz, rolling off 3 dB per octave after that. This curve is found in all motion picture theatres and re-recording stages worldwide.