Cinema’s X-curve standard was based on primitive measurements that ignored better available research

Evidence

The movie industry is an island in the total audio industry. From the outset, the close relationship between the content creators and cinemas was an advantage. The intention was that movie makers and cinema owners would follow the same the industry standards for production and playback loudspeakers and venues. This would ensure consistency in the delivered sound, avoiding the circle of confusion described in Figure 1.8. It was an excellent concept, and standards and calibration methods were established. Unfortunately, the common acoustical measurements of the period were primitive: 1/3- or octave-band analysis of pink noise, yielding steady-state room curves which are not reliable indicators of sound quality at all frequencies. Compounding the problem was the target curve, the so-called X curve, which was an unfortunate choice. There was published research at the time (Ljungberg, 1969) in the Journal of the Society of Motion Picture and Television Engineers (SMPTE) providing better guidance than was employed in defining the X curve that became the standard. Later research confirmed it (Figure 3.14). — Toole, Floyd E, Sound reproduction- the acoustics and…, 356

Categorization

• DEFINE: Defines the X curve as the cinema target curve and explains its problematic origin.
• QUESTION: What exactly was Ljungberg’s 1969 SMPTE guidance, and how did it differ from the X curve?