Multichannel level alignment, part IV: The correlation between physical measures and subjective level calibration

In an effort to establish a better understanding of multichannel level alignment, a correlation and regression analysis has been performed of objective metrics and subjective data collected and subsequently reported in parts I-III & V. This study considers subjective data acquired with 9 test signals with different set-ups considering loudspeaker placement, directivity, reproduction bandwidth and absolute reproduction level. Objective metrics considered include linear and weighted SPL and several loudness metrics. A constant specific loudness signal with a high pass filter at 500 Hz is found to provide the best prediction of subjective level alignment under a wide range of practical usage situations with a wide range of metrics.