If the 00s were the decade of the image in cinema, the 10s are destined to be decade for sound. New cinema sound efforts such as Iosono, Auro-3D, IMM, and DSM are getting attention. But under the hood, a number of initiatives are taking place that are worthy of review.
The x-curve (the “x” originally stood for “experimental”) describes a target response curve to guide technicians when aligning a room. It is formally decscribed in SMPTE ST0202-2010. Because the curve has a roll-off at high frequencies, it often is mistakenly thought of as an equalization curve for sound tracks. Quite the opposite, it’s designed to preserve flat response sound tracks. The roll-off only emulates the typical response found in reverberant rooms. A technician using a real-time analyzer will get closer to the right response using x-curve than not.
X-curve was introduced 35 years ago to bring a higher degree of uniformity to cinema sound than had previously been possible. Since then, more sophisticated measurement methods have become affordable, but no body of work has emerged that describes how to best apply these methods in the cinema. This led to a study group effort in SMPTE, simply titled Theatre B-Chain Study Group. Led by Brian Vessa of Sony Pictures, the group’s task is to seek new measurement methods that will produce more consistency in sound among auditoriums.
This is not a particularly easy thing to achieve. First, it’s necessary to get a group of people to agree on what constitutes good sound. A number of cinema auditoriums are being studied, with experimentation of room measurement methods, and listening tests to determine where group preferences lie. The work has been in progress for 1
