Apparent Source Width Revisited: A Comparative Study of Acoustic Measurements and Perceived Spatial Impression

Previous studies have found that interaural cross-correlation (IACC) and lateral energy fraction (LF) can serve as objective measures to predict apparent source width (ASW). However, there is a lack of literature regarding how well objective measurements correlate with subjective evaluation in a context-dependent scenario. Expanded upon a prior work, this study looked to examine the extent to which commonly assumed predictors of ASW remain valid when applied to real concert hall measurements across listener positions. ASW ratings were obtained through psychoacoustic tests employing both stereo loudspeakers and headphones to assess the perceived width of a symphony orchestra produced with different recording techniques and ensemble sizes. Key room acoustic parameters were calculated from impulse response measurements conducted in the EMPAC concert hall in Troy, NY, where the orchestral recordings were made. Results show that the existence and emergence of ASW is based on the opposite perceptual mappings between the two reproduction conditions, even though stereo loudspeakers resembled real hall listening more closely. The findings also suggest that assuming a fixed role of binaural decorrelation for enhancing ASW is impractical because ASW is governed by context-dependent object integration, where binaural decorrelation is only beneficial when it supports rather than disrupts object unity.