Reports on Progress:
In most of the experiments listeners were asked to evaluate audio quality in terms of the following attributes:
Basic Audio Quality
This is a global attribute that describes any and all detected differences between the reference and the evaluated excerpt.
In this case listeners were asked to grade audio quality according to the difference in timbre between the reference and an evaluated excerpt. Listeners were asked to ignore all changes related to spatial characteristics of sound.
Frontal Spatial Fidelity
This attribute was used to evaluate changes in spatial sound reproduction within the frontal arc (between the left and right loudspeaker).
Surround Spatial Fidelity
In this case listeners were asked to grade each stimulus according to how similar it is to the reference, taking into account changes in spatial sound reproduction outside the frontal arc (not between the left and right loudspeaker). They were asked to ignore timbral changes, as well as any spatial changes inside the frontal arc.