Understanding auditory envelopment and how it could change the way we think about mixing. A conversation with Thomas Lund.

The title is intentionally provocative. It aims to spark curiosity about a topic that may still seem niche yet could reshape how we think about mixing and monitoring. Let me take a step back. At the latest Tonmeistertagung, I had the pleasure of moderating a talk by Thomas Lund, researcher at Genelec and convenor for the European Commission on safe listening. His work focuses on human perception, spatial audio, loudness, and auditory envelopment (AE).

Thomas Lund’s research suggests that low-frequency decorrelation has a profound perceptual impact: not mainly spatial, but emotional. “Some years ago, we made some experiments where we just noticed that everyone—from small children to elderly people with hearing loss—could distinguish between correlated and decorrelated low-frequency sound. So we started thinking about what might explain why everybody has an innate idea of correlated versus uncorrelated sound. “Among other things, we talked about how, when we listen—just like now, as I’m speaking—we perceive a correlation at low frequencies in our head: that’s basically the most common source of correlated sound.” In his studies with participants aged 6 to 90, the correlated low frequencies were described as small, spooky, and dark, while decorrelated bass was perceived as big, pleasant, and light. Lund defines this perceptual dimension as Auditory Envelopment, with a scale from highly correlated (not enveloping) to highly decorrelated (very enveloping).

This also explains why we often dislike hearing our recorded voice. “When we speak, we perceive correlated low frequencies internally through bone conduction: from your stomach up through the neck and through the bones, and our brain knows this pattern intimately. A recording instead captures the voice externally, without that internal resonance, so the low-frequency pattern is different. This is why it sounds strange and unfamiliar.”