On the effect of inter-channel level difference distortions on the perceived subjective quality of stereo signals

Perceptual audio coding at low bitrates and stereo enhancement algorithms can affect perceived quality of stereo audio signals. Besides changes in timbre, also the spatial sound image can be altered, resulting in quality degradations compared to an original reference. While effects of timbre degradation on quality are well-understood, effects of spatial distortions are not sufficiently known. This paper presents a study designed to quantify the effect of Inter-Channel Level Difference (ICLD) errors on perceived audio quality. Results show systematic effects of ICLD errors on quality: bigger ICLD errors led to greater quality degradation. Spectral portions containing relatively higher energy were affected more strongly.