Determination and validation of mix parameters for modifying envelopment in object-based audio

Abstract

Envelopment is an important attribute of listener preference for spatial audio reproduction. Object-based audio offers the possibility of altering the rendering of an audio scene in order to modify or maintain perceptual attributes-including envelopment-if the relationships between attributes and mix parameters are known. In a method of adjustment experiment, mixing engineers were asked to produce mixes of four program items at low, medium, and high levels of envelopment in 2-channel, 5-channel, and 22-channel reproduction systems. The participants could vary a range of level, position, and equalization parameters that can be modified in object-based audio systems. The parameters could be varied separately for different semantic object categories. Nine parameters were found to have significant relationships with envelopment; parameters relating to the horizontal and vertical spread of sources were shown to be most important. A follow-on experiment demonstrated that these parameters can be adjusted to produce a range of envelopment levels in other program items.